Contraceptive use and pregnancy planning in Britain during the first year of the COVID-19 pandemic: findings from a large, quasi-representative survey (Natsal-COVID) (preprint)

Background Reproductive health services were significantly disrupted during the COVID-19 pandemic in Britain. We investigated contraception-related health inequalities in the first year of the pandemic. Methods Natsal-COVID Wave 2 surveyed 6,658 adults aged 18-59 between March-April 2021, using quotas and weighting to achieve quasi-representativeness. Our analysis included sexually active participants aged 18-44, described as female at birth. We analysed contraception use and switching, contraceptive service access, and pregnancy plannedness in the year from March 2020. Findings Amongst all participants (n=1,488), 14.3% (12.5%-16.3%) reported switching or stopping contraception due to the pandemic. Of participants at risk of unplanned pregnancy (n=1,169), 54.1% (51.0%-57.1%) reported routinely using effective contraception in the past year. 3.2% (2.0%-5.1%) of those using effective methods pre-pandemic switched to less effective methods, while 3.8% (2.5%-5.9%) stopped. Stopping/switching was more likely amongst participants of younger age, non-white ethnicity, and lower social grade. 29.3% of at-risk participants (26.9%-31.8%) reported trying to access contraceptive services; of whom 16.4% (13.0%-20.4%) reported their needs went unmet. Unmet need was associated with younger age, diverse sexual identities and anxiety symptoms. Of 199 pregnancies, 6.6% (3.9%-11.1%) were scored as 'unplanned'; less planning was associated with younger age, lower social grade and unemployment. Interpretation Although many participants reported accessing contraceptive services during the pandemic, one-in-six of these reported an unmet need. Inequalities in unmet need and risk of unplanned pregnancy - related to age, ethnicity, social disadvantage and mental health - potentially exacerbated existing reproductive health inequalities. These should be addressed in the post-pandemic period and beyond.

How did the COVID-19 pandemic affect access to condoms, chlamydia and HIV testing, and cervical cancer screening at a population level in Britain? (Natsal-COVID) (preprint)

Objectives: To investigate how differential access to key interventions to reduce sexually transmitted infections (STI), HIV, and their sequelae changed during the COVID-19 pandemic. Methods: British participants (18-59y) completed a cross-sectional web survey one year (March to April 2021) after the initial lockdown in Britain. Quota-based sampling and weighting resulted in a quasi-representative population sample. We compared Natsal-COVID data with Natsal-3, a household-based probability sample cross-sectional survey (16-74y) conducted in 2010-12. Reported unmet need for condoms because of the pandemic and uptake of chlamydia testing/HIV testing/cervical cancer screening were analysed among sexually-experienced participants (18-44y) (n=2869, Natsal-COVID; n=8551, Natsal-3). Odds ratios adjusted for age (aOR) and other potential confounders (AOR) describe associations with demographic and behavioural factors. Results: In 2021, 6.9% of women and 16.2% of men reported unmet need for condoms because of the pandemic. This was more likely among participants: aged 18-24 years, of Black or Black British ethnicity, and reporting same-sex sex (past five years) or one or more new relationships (past year). Chlamydia and HIV testing were more commonly reported by younger participants, those reporting condomless sex with new sexual partners, and men reporting same-sex partners; a very similar distribution to 10 years previously (Natsal-3). However, there were differences during the pandemic, including stronger associations with chlamydia testing for men reporting same-sex partners; with HIV testing for women reporting new sexual partners; and with cervical screening among smokers. Conclusions: Our study suggests differential access to key primary and secondary STI/HIV prevention interventions continued during the first year of the COVID-19 pandemic. However, the available evidence does not suggest substantial changes in inequalities in since 2010-12. While the pandemic might not have exacerbated inequalities in access to primary and secondary prevention, it is clear that large inequalities persisted, typically among those at greatest STI/HIV risk.

Statistical and agent-based modelling of the transmissibility of different SARS-CoV-2 variants in England and impact of different interventions (preprint)

The English SARS-CoV-2 epidemic has been affected by the emergence of new viral variants such as B.1.177, Alpha and Delta, and changing restrictions. We used statistical models and calibration of an stochastic agent-based model Covasim to estimate B.1.177 to be 20% more transmissible than the wild type, Alpha to be 50-80% more transmissible than B.1.177 and Delta to be 65-90% more transmissible than Alpha. We used these estimates in Covasim (calibrated between September 01, 2020 and June 20, 2021), in June 2021, to explore whether planned relaxation of restrictions should proceed or be delayed. We found that due to the high transmissibility of Delta, resurgence in infections driven by the Delta variant would not be prevented, but would be strongly reduced by delaying the relaxation of restrictions by one month and with continued vaccination.

Transmission of SARS-CoV-2 by children and young people in households and schools: a meta-analysis of population-based and contact-tracing studies (preprint)

Background The role of children and young people (CYP) in transmission of SARS-CoV-2 in household and educational settings remains unclear. We undertook a systematic review and meta-analysis of contact-tracing and population-based studies at low risk of bias. Methods We searched 4 electronic databases on 28 July 2021 for contact-tracing studies and population-based studies informative about transmission of SARS-CoV-2 from 0-19 year olds in household or educational settings. We excluded studies at high risk of bias, including from under-ascertainment of asymptomatic infections. We undertook multilevel random effects meta-analyses of secondary attack rates (SAR: contact-tracing studies) and school infection prevalence, and used meta-regression to examine the impact of community SARS-CoV-2 incidence on school infection prevalence. Findings 4529 abstracts were reviewed, resulting in 37 included studies (16 contact-tracing; 19 population studies; 2 mixed studies). The pooled relative transmissibility of CYP compared with adults was 0.92 (0.68, 1.26) in adjusted household studies. The pooled SAR from CYP was lower (p=0.002) in school studies 0.7% (0.2, 2.7) than household studies (7.6% (3.6, 15.9) . There was no difference in SAR from CYP to child or adult contacts. School population studies showed some evidence of clustering in classes within schools. School infection prevalence was associated with contemporary community 14-day incidence (OR 1.003 (1.001, 1.004), p<0.001). Interpretation We found no difference in transmission of SARS-CoV-2 from CYP compared with adults within household settings. SAR were markedly lower in school compared with household settings, suggesting that household transmission is more important than school transmission in this pandemic. School infection prevalence was associated with community infection incidence, supporting hypotheses that school infections broadly reflect community infections. These findings are important for guiding policy decisions on shielding, vaccination school and operations during the pandemic.

Access and quality of sexual and reproductive health (SRH) services in Britain during the early stages of the COVID-19 pandemic: a qualitative interview study of patient experiences (preprint)

Objectives: Access to quality sexual and reproductive health (SRH) services remains imperative, even during a pandemic. Our objective was to understand experiences of delayed or unsuccessful access to SRH services in Britain during the early stages of COVID-19 pandemic. Design: Semi-structured qualitative follow-up interviews were conducted in October-November 2020 (six months after the first UK lockdown) with participants of Natsal-COVID, a quasi-representative web-panel survey of sexual health and behaviour during COVID-19 (n=6654). Inductive thematic analysis was used to identify lessons for future SRH service access and quality. Setting: Telephone interviews with participants from the general population. Participants: 14 women and 6 men (24-47-years-old) reporting unmet need for SRH services and agreeing to recontact (n=311) were selected for interview using socio-demographic quotas. Results: Participant experiences spanned ten different SRH services, including contraception and antenatal/maternity services. At interview, ten participants still experienced unmet need. Participants reported hesitancy and self-censorship of need. Accessing services required tenacity. Challenges included navigating inconsistent information and changing procedures; perceptions of gatekeepers as obstructing access; and inflexible appointment systems. Concerns about reconfigured services included reduced privacy; decreased quality of interactions with professionals; reduced informal support due to lone attendance; and fewer routine physical checks. However, participants also described examples of more streamlined services and staff efforts to compensate for disruptions. Many viewed the blending of telemedicine with in-person care as a positive development. Conclusion: COVID-19 impacted access and quality of SRH services. The accounts of those who struggled to access services revealed self-censorship of need, difficulty navigating shifting service configurations, and perceived reduction in quality due to a socially-distanced service model. Telemedicine offers potential for greater efficiency if blended intelligently with in-person care. We offer some initial data-based recommendations for promoting equitable access and quality in restoration and future adaption of SRH services.

Implementation of COVID-19 Preventive Measures in Primary and Secondary Schools Following Reopening of Schools in Autumn 2020; A Cross-Sectional Study of Parents' and Teachers' Experiences in England (preprint)

Objective The main objective was to assess implementation of and ease of implementation of control measures in schools as reported by staff and parents. Design Cross-sectional study. Setting Staff and parents/guardian participants in the 132 primary schools and 20 secondary schools participating in sKIDs and sKIDsPLUS surveillances. Main outcome measure Prevalence of control measures implemented in Autumn 2020, parental and staff perception of ease of implementation and acceptability of conducting school surveillance studies. Results In total, 56/152 (37%) schools participating in Public Health England's sKIDs study of COVID in schools accepted the invitation to participate in the survey. By 28 December 2020, 1,953 parent and 986 staff respondents had completed the online questionnaire. While more than half the parents were positive about their children returning to school, roughly a third reported being a little anxious. 90% and 82% of primary and secondary school parents were either completely or partly reassured by the preventive measures implemented in their schools. Among staff, 80% of primary staff and 87% of secondary school staff felt that they were at higher risk of COVID-19 because of their profession; only 52% of primary school staff and 38% of secondary school staff reportedly felt safe. According to the teaching staff, most preventive measures were well-implemented apart from requiring 2-metre distancing between staff. For students, maintaining the 2-metre distance was reported to be particularly difficult. By extension, secondary schools also struggled to maintain small groups at all times or ensuring that the same staff were assigned to each student group (a problem also commonly reported by parents). Conclusions Variable implementation of infection control measures was reported by staff and parents. Whilst the majority were not worried about returning to school, some parents and staff, were concerned about returning to school and the risks posed to children, staff and household members.

Modelling the impact of reopening schools in early 2021 in the presence of the new SARS-CoV-2 variant and with roll-out of vaccination against COVID-19 (preprint)

Background Following the resurgence of the COVID-19 epidemic in the UK in late 2020 and the emergence of the new variant of the SARS-CoV-2 virus, B.1.1.7, a third national lockdown was imposed from January 5, 2021. Following the decline of COVID-19 cases over the remainder of January 2021, it is important to assess the conditions under which reopening schools from early March is likely to lead to resurgence of the epidemic. This study models the impact of a partial national lockdown with social distancing measures enacted in communities and workplaces under different strategies of reopening schools from March 8, 2021 and compares it to the impact of continual full national lockdown remaining until April 19, 2021. Methods We used our previously published model, Covasim, to model the emergence of B.1.1.7 over September 1, 2020 to January 31, 2021. We extended the model to incorporate the impacts of the roll-out of a two-dose vaccine against COVID-19, assuming 200,000 daily doses of the vaccine in people 75 years or older with vaccination that offers 95% reduction in disease acquisition and 10% reduction of transmission blocking. We used the model, calibrated until January 25, 2021, to simulate the impact of a full national lockdown (FNL) with schools closed until April 19, 2021 versus four different partial national lockdown (PNL) scenarios with different elements of schooling open: 1) staggered PNL with primary schools and exam-entry years (years 11 and 13) returning on March 8, 2021 and the rest of the schools years on March 15, 2020; 2) full-return PNL with both primary and secondary schools returning on March 8, 2021; 3) primary-only PNL with primary schools and exam critical years (Y11 and Y13) going back only on March 8, 2021 with the rest of the secondary schools back on April 19, 2021 and 4) part-Rota PNL with both primary and secondary schools returning on March 8, 2021 with primary schools remaining open continuously but secondary schools on a two-weekly rota-system with years alternating between a fortnight of face-to-face and remote learning until April 19, 2021. Across all scenarios, we projected the number of new daily cases, cumulative deaths and effective reproduction number R until April 30, 2020. Results Our calibration across different scenarios is consistent with the new variant B.1.1.7 being around 60% more transmissible. Strict social distancing measures, i.e. national lockdowns, are required to contain the spread of the virus and control the hospitalisations and deaths during January and February 2021. The national lockdown will reduce the number of cases by early March levels similar to those seen in October with R also falling and remaining below 1 during the lockdown. Infections start to increase when schools open but if other parts of society remain closed this resurgence is not sufficient to bring R above 1. Reopening primary schools and exam critical years only or having primary schools open continuously with secondary schools on rotas will lead to lower increases in cases and R than if all schools open. Under the current vaccination assumptions and across the set of scenarios considered, R would increase above 1 if society reopens simultaneously, simulated here from April 19, 2021.Findings Our findings suggest that stringent measures are necessary to mitigate the increase in cases and bring R below 1 over January and February 2021. It is plausible that a PNL with schools partially open from March 8, 2021 and the rest of the society remaining closed until April 19, 2021 may keep R below 1, with some increase evident in infections compared to continual FNL until April 19, 2021. Reopening society in mid-April, with the vaccination strategy we model, could push R above 1 and induce a surge in infections, but the effect of vaccination may be able to control this in future depending on the transmission blocking properties of the vaccines.

Impacts of school closures on physical and mental health of children and young people: a systematic review (preprint)

Background The well-documented links between education and health mean that school closures during the COVID-19 pandemic are likely to be associated with significant health harms to children and young people (CYP). A systematic review of the evidence is needed to inform policy decisions around school closures and re-openings during the pandemic. Methods We undertook a high-quality systematic review of observational quantitative studies (published or preprint) of the impacts of school closures (for any reason) on the health, wellbeing and educational outcomes of CYP, excluding impacts of closure on transmission of infection (PROSPERO CRD42020181658). We used a machine learning approach for screening articles, with decisions on inclusion and data extraction performed independently by 2 researchers. Quality was assessed for study type. A narrative synthesis of results was undertaken as data did not allow meta-analysis. Results 16,817 records were screened, of which 151 were reviewed in full-text and 72 studies were included from 20 countries. 33% were cohort studies using historical control periods; 19% pre-post studies; and 46% cross-sectional studies which assessed change by comparison with population reference data. 63% were high-quality, 25% medium-quality and 13% low-quality. Cause of closure in all studies was the first COVID-19 pandemic wave with the exception of 5 influenza studies and 1 teacher strike. 27 studies concerning mental health identified considerable impacts across emotional, behavioural and restlessness/inattention problems; 18-60% of CYP scored above risk thresholds for distress, particularly anxiety and depressive symptoms. Two studies reported non-significant rises in suicide rates. Self-harm and psychiatric attendances were markedly reduced, indicating a rise in unmet mental health need. Child protection referrals fell 27-39%, with a halving of the expected number of referrals originating in schools. 19 studies concerning health service use showed marked reductions in emergency department (ED) presentations and hospital admissions, with evidence of delayed presentations and potential widening of inequalities in vaccination coverage. Data suggested marked rises in screen-time and social media use and reductions in physical activity however data on sleep and diet were inconclusive. Available data suggested likely higher harms in CYP from more deprived populations. Conclusions School closures as part of broader social distancing measures are associated with considerable harms to CYP health and wellbeing. Available data are short-term and longer-term harms are likely to be magnified by further school closures. Data are urgently needed on longer-term impacts using strong research designs, particularly amongst vulnerable groups. These findings are important for policy-makers seeking to balance the risks of transmission through school-aged children with the harms of closing schools.

Modelling the impact of reopening schools in early 2021 in the presence of the new SARS-CoV-2 variant and with roll-out of vaccination against COVID-19 (preprint)

Background Following the resurgence of the COVID-19 epidemic in the UK in late 2020 and the emergence of the new variant of the SARS-CoV-2 virus, B.1.1.7, a third national lockdown was imposed from January 5, 2021. Following the decline of COVID-19 cases over the remainder of January 2021, it is important to assess the conditions under which reopening schools from early March is likely to lead to resurgence of the epidemic. This study models the impact of a partial national lockdown with social distancing measures enacted in communities and workplaces under different strategies of reopening schools from March 8, 2021 and compares it to the impact of continual full national lockdown remaining until April 19, 2021. Methods We used our previously published model, Covasim, to model the emergence of B.1.1.7 over September 1, 2020 to January 31, 2021. We extended the model to incorporate the impacts of the roll-out of a two-dose vaccine against COVID-19, assuming 200,000 daily doses of the vaccine in people 75 years or older with vaccination that offers 95% reduction in disease acquisition and 10% reduction of transmission blocking. We used the model, calibrated until January 25, 2021, to simulate the impact of a full national lockdown (FNL) with schools closed until April 19, 2021 versus four different partial national lockdown (PNL) scenarios with different elements of schooling open: 1) staggered PNL with primary schools and exam-entry years (years 11 and 13) returning on March 8, 2021 and the rest of the schools years on March 15, 2020; 2) full-return PNL with both primary and secondary schools returning on March 8, 2021; 3) primary-only PNL with primary schools and exam critical years (Y11 and Y13) going back only on March 8, 2021 with the rest of the secondary schools back on April 19, 2021 and 4) part-Rota PNL with both primary and secondary schools returning on March 8, 2021 with primary schools remaining open continuously but secondary schools on a two-weekly rota-system with years alternating between a fortnight of face-to-face and remote learning until April 19, 2021. Across all scenarios, we projected the number of new daily cases, cumulative deaths and effective reproduction number R until April 30, 2020. Results Our calibration across different scenarios is consistent with the new variant B.1.1.7 being around 60% more transmissible. Strict social distancing measures, i.e. national lockdowns, are required to contain the spread of the virus and control the hospitalisations and deaths during January and February 2021. The national lockdown will reduce the number of cases by early March levels similar to those seen in October with R also falling and remaining below 1 during the lockdown. Infections start to increase when schools open but if other parts of society remain closed this resurgence is not sufficient to bring R above 1. Reopening primary schools and exam critical years only or having primary schools open continuously with secondary schools on rotas will lead to lower increases in cases and R than if all schools open. Under the current vaccination assumptions and across the set of scenarios considered, R would increase above 1 if society reopens simultaneously, simulated here from April 19, 2021. Findings Our findings suggest that stringent measures are necessary to mitigate the increase in cases and bring R below 1 over January and February 2021. It is plausible that a PNL with schools partially open from March 8, 2021 and the rest of the society remaining closed until April 19, 2021 may keep R below 1, with some increase evident in infections compared to continual FNL until April 19, 2021. Reopening society in mid-April, with the vaccination strategy we model, could push R above 1 and induce a surge in infections, but the effect of vaccination may be able to control this in future depending on the transmission blocking properties of the vaccines.

Do school closures reduce community transmission of COVID-19? A systematic review of observational studies (preprint)

IntroductionSchool closures are associated with significant negative consequences and may exacerbate inequalities. They were implemented worldwide to control SARS-CoV-2 in the first half of 2020, but their effectiveness remains uncertain. This review summarises the empirical evidence of their effect on SARS-CoV-2 community transmission. MethodsThe study protocol was registered on Prospero (ID:CRD42020213699). On 12 October 2020 we searched PubMed, Web of Science, Scopus, CINAHL, the WHO Global COVID-19 Research Database, ERIC, the British Education Index, and the Australian Education Index. We included empirical studies with quantitative estimates of the effect of school closures/reopenings on SARS-CoV-2 community transmission. We excluded prospective modelling studies and intra-school transmission studies. We performed a narrative synthesis due to data heterogeneity. ResultsWe identified 3,318 articles, of which ten were included, with data from 146 countries. All studies assessed school closures, and one additionally examined re-openings. There was substantial heterogeneity between studies. Three studies, including the two at lowest risk of bias, reported no impact of school closures on SARS-CoV-2 transmission; whilst the other seven reported protective effects. Effect sizes ranged from no association to substantial and important reductions in community transmission. DiscussionStudies were at risk of confounding and collinearity from other non-pharmacological interventions implemented close to school closures. Our results are consistent with school closures being ineffective to very effective. This variation may be attributable to differences in study design or real differences. With such varied evidence on effectiveness, and the harmful effects, policymakers should take a measured approach before implementing school closures. Panel: Research in contextO_ST_ABSEvidence before this studyC_ST_ABSA previous systematic review, published by some of us in April 2020, found good evidence that school closures are effective for the control of influenza, but limited evidence of effectiveness for coronavirus outbreaks. At the time there was no available empirial evidence from the COVID-19 pandemic. Added value of this studyThis study is the first systematic review of the empirical evidence from observational studies of the effect of school closures and reopenings on community transmission of SARS-CoV-2. We include 10 studies, covering 146 countries. There was significant heterogeneity between studies. Some studies reported large reductions in incidence and mortality associated with school closures, however, studies were at risk of confounding and collinearity, and studies at lower risk of bias reported no association. Implications of all the available evidenceThe evidence is consistent with either no effect, or a protective effect of school closures. With such varied evidence on effectiveness, and the harmful effects, policymakers should take a measured approach before implementing school closures.

The potential contribution of face coverings to the control of SARS-CoV-2 transmission in schools and broader society in the UK: a modelling study (preprint)

Recent findings suggest that an adequate test-trace-isolate (TTI) strategy is needed to prevent a secondary COVID-19 wave with the reopening of society in the UK. Here we assess the potential importance of mandatory masks in the parts of community and in secondary schools. We show that, assuming current TTI levels, adoption of masks in secondary schools in addition to community settings can reduce the size of a second wave, but will not prevent it; more testing of symptomatic people, tracing and isolating of their contacts is also needed. To avoid a second wave, with masks mandatory in secondary schools and in certain community settings, under current tracing levels, 68% or 46% of those with symptomatic infection would need to be tested if masks' effective coverage were 15% or 30% respectively, compared to 76% and 57% if masks are mandated in community settings but not secondary schools.

Using volunteered geographic information to assess mobility in the COVID-19 pandemic context: cross-city time series analysis of 41 cities in 22 countries from March 2nd to 26th 2020 (preprint)

Objectives: Restricting mobility is a central aim for lowering contact rates and preventing COVID-19 transmission. Yet the impact on mobility of different non-pharmaceutical countermeasures in the earlier stages of the pandemic is not well-understood. Design: Trends were evaluated using Citymapper’s mobility index covering 2 nd to 26 th March 2020, expressed as percentages of typical usage periods from 0% as the lowest and 100% as normal. China and India were not covered. Multivariate fixed effects models were used to estimate the association of policies restricting movement on mobility before and after their introduction. Policy restrictions were assessed using the Oxford COVID-19 Government Response Stringency Index as well as measures coding the timing and degree of school and workplace closures, transport restrictions, and cancellation of mass gatherings. Setting: 41 cities worldwide Main outcome measures: Citymapper’s mobility index Results: : Mobility declined in all major cities throughout March. Larger declines were seen in European than Asian cities. The COVID-19 Government Response Stringency Index was strongly associated with declines in mobility (r = -0.75, p<0.001). After adjusting for time-trends, we observed that implementing non-pharmaceutical countermeasures was associated with a decline of mobility of 10.0% for school closures (95% CI: 4.36% to 15.7%), 15.0% for workplace closures (95% CI: 10.2% to 19.8%), 7.09% for cancelling public events (95% CI: 1.98% to 12.2%), 18.0% for closing public transport (95% CI: 6.74% to 29.2%), 13.3% for restricting internal movements (95% CI: 8.85% to 17.8%) and 5.30% for international travel controls (95% CI: 1.69 to 8.90). In contrast, as expected, there was no association between population mobility changes and fiscal or monetary measures or emergency healthcare investment. Conclusions: : Understanding the effect of public policy on mobility in the early stages is crucial to slowing and reducing COVID-19 transmission. By using Citymapper’s mobility index, this work provides the first evidence about trends in mobility and the impacts of different policy interventions, suggesting that closure of public transport, workplaces and schools are particularly impactful. Summary: box What is already known on this topic? Governments across the global are experimenting with a range of policy interventions to restrict movement in populations. Yet their impact is not well understood. There is an urgent need to understand how alternative policy approaches to restricting movement can impact on population mobility trends. What this study adds Our study finds that policy restrictions markedly reduced population-wide mobility. Closing public transport, workplaces and schools have among the largest associations with mobility declines.

Modelling the Health and Economic Impacts of Population-Wide Testing, Contact Tracing and Isolation (PTTI) Strategies for COVID-19 in the UK (preprint)

Background: The COVID-19 epidemic in the UK has resulted in over 280,000 reported cases and over 40,000 deaths as of 5th June 2020. In the context of a slower increase in reported cases and deaths associated with COVID-19 over the last few weeks compared to earlier in the epidemic, the UK is starting to relax the physical restrictions (‘lockdown’) that have been imposed since 23 March 2020. This has been accompanied by the announcement of a strategy to test people for infection, trace contacts of those tested positive, and isolate positive diagnoses. While such policies are expected to be impactful, there is no conclusive evidence of which approach to this is likely to achieve the most appropriate balance between benefits and costs. This study combines mathematical and economic modelling to estimate the impact, costs, feasibility, and health and economic effects of different strategies. Methods: We provide detailed description, impact, costing, and feasibility assessment of population-scale testing, tracing, and isolation strategies (PTTI). We estimate the impact of different PTTI strategies with a deterministic mathematical model for SARS-CoV-2 transmission that accurately captures tracing and isolation of contacts of individuals exposed, infectious, and diagnosed with the virus. We combine this with an economic model to project the mortality, intensive care, hospital, and non-hospital case outcomes, costs to the UK National Health Service, reduction in GDP, and intervention costs of each strategy. Model parameters are derived from publicly available data, and the model is calibrated to reported deaths associated with COVID-19. We modelled 31 scenarios in total (Panel 2). The first 18 comprised nine with ‘triggers’ (labelled with the -Trig suffix) for subsequent lockdown periods (>40,000 new infections per day) and lockdown releases (<10,000 new infections per day), and nine corresponding scenarios without triggers, namely: no large-scale PTTI (scenario 1); scale-up of PTTI to testing the whole population every week, with May–July 2020 lockdown release (scenario 2b), or delayed lockdown release until scale-up complete on 31 August 2020 (scenario 2a); these two scenarios with mandatory use of face coverings (scenarios 3a and 3b); and scenarios 2a, 2b, 3a, 3b replacing untargeted PTTI with testing of symptomatic people only (scenarios 4a, 4b, 4c, 4d). The final 13 scenarios looked at: whole population weekly testing to suppress the epidemic with lower tracing success (scenarios 3b-Trig00, 3b-Trig10, 3b-Trig20, 3b-Trig30) and switched to targeted testing after two months when it may suppress the epidemic (scenarios 3b-Trig00-2mo and 3b-Trig30-2mo), and targeted testing with lower tracing success (scenarios 4d-Trig10, 4dTrig20, 4d-Trig30, 4d-Trig40, 4d-Trig50, 4d-Trig60, 4d-Trig70). Findings: Given that physical distancing measures have already been relaxed in the UK, scenario 4d-Trig (targeted testing of symptomatic people only, with a mandatory face coverings policy and subsequent lockdown triggered to enable PTTI to suppress the epidemic), is a strategy that will result in the fewest deaths (~52,000) and has the lowest intervention costs (~£8bn). The additional lockdown results in total reduction in GDP of ~£503bn, less than half the cost to the economy of subsequent lockdowns triggered in a scenario without PTTI (scenario 1-Trig, ~£1180bn reduction in GDP, ~105,000 deaths). In summer months, with lower cold and flu prevalence, approximately 75,000 symptomatic people per day need to be tested for this strategy to work, assuming 64% of their contacts are effectively traced (~80% traced with 80% success) within the infectious period (most within the first two days and nearly all by seven days) and all are isolated – including those without any symptoms – for 14 days. Untargeted testing of everyone every week, if it were feasible, may work without tracing, but at a higher cost (scenario 3b-Trig00). This cost could be reduced by switching to targeted testing after the epidemic is suppressed (scenario 3b-Trig30-2mo), though we note the epidemic could be suppressed with targeted testing itself providing tracing and isolation has at least a 32% success rate (scenario 4dTrig40). Interpretation: PTTI strategies to suppress the COVID-19 epidemic within the context of a relaxation of lockdown will necessitate subsequent lockdowns to keep the epidemic suppressed during PTTI scale-up. Targeted testing of symptomatic people only can suppress the epidemic if accompanied by mandated use of face coverings. The feasibility of PTTI depends on sufficient capacity, capabilities, infrastructure and integrated systems to deliver it. The political and public acceptability of alternative scenarios for subsequent lockdowns needs to take account of crucial implications for employment, personal and national debt, education, population mental health and non-COVID-19 disease. Our model is able to incorporate additional scenarios as the situation evolves. Funding: No specific funding was received in support of this study. Grant support for specific authors is as follows: WW acknowledges support from the Chief Scientist Office (COV/EDI/20/12) RR, JPG and EP are supported by the National Institute for Health Research ARC North Thames. NMcG is a recipient of an NIHR Global Health Research Professorship award (Ref: RP-2017-08-ST2-008). The views expressed in this independent research are those of the authors and not necessarily those of the National Institute for Health Research or the Department of Health and Social Care. KMG is supported by the UK Medical Research Council (MC_UU_12011/4), the National Institute for Health Research (NIHR Senior Investigator (NF-SI-0515-10042) and NIHR Southampton Biomedical Research Centre (IS-BRC-1215-20004)), British Heart Foundation (RG/15/17/3174) and the US National Institute On Aging of the National Institutes of Health (Award No. U24AG047867). GY acknowledges her research partially supported from the Newton Fund through a UK-China ARM Partnership Hub award (No:MR/S013717/1).Declaration of Interests: All authors declare no competing interests.

How to Set up Government-Led National Hygiene Communication Campaigns to Combat COVID-19: A Strategic Blueprint (preprint)

Whilst large-scale changes in population behaviour are required to reduce the transmission of the SARS-COV-2 virus, the emergency context is not conducive to the sort of careful communications planning that would normally be required to meet such a task. Rapid strategic communications planning in a pandemic by governments is, however, possible and necessary. Steps include setting up a dedicated communications task force, mobilising partners and resources, developing a creative brief and theory of change and overseeing the creation, testing, roll out and revision of content. In this short guide we argue that a minimum of strategic planning can be undertaken rapidly, and that good use can be made of simple principles of behaviour change, even during pandemics. Our aim here is to provide a blueprint that governments and their partners, especially in low-income settings, can follow to design, coordinate and resource national communications efforts to combat the COVID-19 pandemic immediately and for the longer term.

Determining the optimal strategy for reopening schools, work and society in the UK: balancing earlier opening and the impact of test and trace strategies with the risk of occurrence of a secondary COVID-19 pandemic wave (preprint)

Background In order to slow down the spread of SARS-CoV-2, the virus causing the COVID-19 pandemic, the UK government has imposed strict physical distancing (lockdown) measures including school 'dismissals' since 23 March 2020. As evidence is emerging that these measures may have slowed the spread of the pandemic, it is important to assess the impact of any changes in strategy, including scenarios for school reopening and broader relaxation of social distancing. This work uses an individual-based model to predict the impact of a suite of possible strategies to reopen schools in the UK, including that currently proposed by the UK government. Methods We use Covasim, a stochastic agent-based model for transmission of COVID-19, calibrated to the UK epidemic. The model describes individuals' contact networks stratified as household, school, work and community layers, and uses demographic and epidemiological data from the UK. We simulate a range of different school reopening strategies with a society-wide relaxation of lockdown measures and in the presence of different non-pharmaceutical interventions, to estimate the number of new infections, cumulative cases and deaths, as well as the effective reproduction number with different strategies. To account for uncertainties within the stochastic simulation, we also simulated different levels of infectiousness of children and young adults under 20 years old compared to older ages. Findings We found that with increased levels of testing of people (between 25% and 72% of symptomatic people tested at some point during an active COVID-19 infection depending on scenarios) and effective contact-tracing and isolation for infected individuals, an epidemic rebound may be prevented across all reopening scenarios, with the effective reproduction number (R) remaining below one and the cumulative number of new infections and deaths significantly lower than they would be if testing did not increase. If UK schools reopen in phases from June 2020, prevention of a second wave would require testing 51% of symptomatic infections, tracing of 40% of their contacts, and isolation of symptomatic and diagnosed cases. However, without such measures, reopening of schools together with gradual relaxing of the lockdown measures are likely to induce a secondary pandemic wave, as are other scenarios for reopening. When infectiousness of <20 year olds was varied from 100% to 50% of that of older ages, our findings remained unchanged. Interpretation To prevent a secondary COVID-19 wave, relaxation of social distancing including reopening schools in the UK must be implemented alongside an active large-scale population-wide testing of symptomatic individuals and effective tracing of their contacts, followed by isolation of symptomatic and diagnosed individuals. Such combined measures have a greater likelihood of controlling the transmission of SARS-CoV-2 and preventing a large number of COVID-19 deaths than reopening schools and society with the current level of implementation of testing and isolation of infected individuals.

Susceptibility to and transmission of COVID-19 amongst children and adolescents compared with adults: a systematic review and meta-analysis (preprint)

ImportanceThe degree to which children and young people are infected by and transmit the SARS-CoV-2 virus is unclear. The role of children and young people in transmission of SARS-CoV-2 is dependent on susceptibility, symptoms, viral load, social contact patterns and behaviour. ObjectiveWe undertook a rapid systematic review to address the question "What is the susceptibility to and transmission of SARS-CoV-2 by children and adolescents compared with adults?" Data sourcesWe searched PubMed and medRxiv up to 28 July 2020 and identified 13,926 studies, with additional studies identified through handsearching of cited references and professional contacts. Study SelectionWe included studies which provided data on the prevalence of SARS-CoV-2 in children and young people (<20 years) compared with adults derived from contact-tracing or population-screening. We excluded single household studies. Data extraction and SynthesisWe followed PRISMA guidelines for abstracting data, independently by 2 reviewers. Quality was assessed using a critical appraisal checklist for prevalence studies. Random effects meta-analysis was undertaken. Main OutcomesSecondary infection rate (contact-tracing studies) or prevalence or seroprevalence (population-screening studies) amongst children and young people compared with adults. Results32 studies met inclusion criteria; 18 contact-tracing and 14 population-screening. The pooled odds ratio of being an infected contact in children compared with adults was 0.56 (0.37, 0.85) with substantial heterogeneity (95%). Three school contact tracing studies found minimal transmission by child or teacher index cases. Findings from population-screening studies were heterogenous and were not suitable for meta-analysis. The majority of studies were consistent with lower seroprevalence in children compared with adults, although seroprevalence in adolescents appeared similar to adults. ConclusionsThere is preliminary evidence that children and young people have lower susceptibility to SARS-CoV-2, with a 43% lower odds of being an infected contact. There is weak evidence that children and young people play a lesser role in transmission of SARS-CoV-2 at a population level. Our study provides no information on the infectivity of children. Key pointsO_ST_ABSQuestionC_ST_ABSWhat is the evidence on the susceptibility and transmission of children and young people to SARS-CoV-2 in comparison with adults? FindingsIn this systematic review and meta-analysis, children and young people under 18-20 years had an 435 lower odds of secondary infection of with SARS-CoV-2 compared to adults 20 years plus, a significant difference. This finding was most marked in children under 12-14 years. Data were insufficient to conclude whether transmission of SARS-CoV-2 by children is lower than by adults. MeaningWe found preliminary evidence that children have a lower susceptibility for SARS-CoV-2 infection compared with adults, although data for adolescents is less clear. The role that children and young people play in transmission of this pandemic remains unclear.

Strategic Thinking in a Pandemic: A Blueprint for Government-Led National Hygiene Communication Campaigns to Combat COVID-19 (preprint)

Whilst large-scale changes in population behaviour are required to reduce the transmission of the SARS-COV-2 pandemic virus, the emergency context is not conducive to the sort of careful communications planning that would normally be required to meet such a task. Rapid strategic communications planning in a pandemic by governments is, however, possible and necessary. Steps include setting up a dedicated communications task force, mobilising partners and resources, developing a creative brief and theory of change and overseeing the creation, testing, roll out and revision of content. In this short guide we argue that a minimum of strategic planning can be undertaken rapidly, and that good use can be made of simple principles of behaviour change, even during pandemics. Our aim here is to provide a blueprint that governments and their partners, especially in low-income settings, can follow to design, coordinate and resource national communications efforts to combat the COVID-19 pandemic.