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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-329911

ABSTRACT

Between June and August 2020, an agent-based model was used to project rates of COVID-19 infection incidence and cases diagnosed as positive from 15 September to 31 October 2020 for 72 geographic settings. Five scenarios were modelled: a baseline scenario where no future changes were made to existing restrictions, and four scenarios representing small or moderate changes in restrictions at two intervals. Post hoc, upper and lower bounds for number of diagnosed Covid-19 cases were compared with actual data collected during the prediction window. A regression analysis with 17 covariates was performed to determine correlates of accurate projections. It was found that the actual data fell within the lower and upper bounds in 27 settings and out of bounds in 45 settings. The only statistically significant predictor of actual data within the predicted bounds was correct assumptions about future policy changes (OR = 15.04;95%CI 2.20-208.70;p = 0.016). Frequent changes in restrictions implemented by governments, which the modelling team was not always able to predict, in part explains why the majority of model projections were inaccurate compared with actual outcomes and supports revision of projections when policies are changed as well as the importance of modelling teams collaborating with policy experts.

2.
PLoS One ; 16(12): e0260820, 2021.
Article in English | MEDLINE | ID: covidwho-1581771

ABSTRACT

INTRODUCTION: The COVID-19 pandemic has caused widespread disruptions including to health services. In the early response to the pandemic many countries restricted population movements and some health services were suspended or limited. In late 2020 and early 2021 some countries re-imposed restrictions. Health authorities need to balance the potential harms of additional SARS-CoV-2 transmission due to contacts associated with health services against the benefits of those services, including fewer new HIV infections and deaths. This paper examines these trade-offs for select HIV services. METHODS: We used four HIV simulation models (Goals, HIV Synthesis, Optima HIV and EMOD) to estimate the benefits of continuing HIV services in terms of fewer new HIV infections and deaths. We used three COVID-19 transmission models (Covasim, Cooper/Smith and a simple contact model) to estimate the additional deaths due to SARS-CoV-2 transmission among health workers and clients. We examined four HIV services: voluntary medical male circumcision, HIV diagnostic testing, viral load testing and programs to prevent mother-to-child transmission. We compared COVID-19 deaths in 2020 and 2021 with HIV deaths occurring now and over the next 50 years discounted to present value. The models were applied to countries with a range of HIV and COVID-19 epidemics. RESULTS: Maintaining these HIV services could lead to additional COVID-19 deaths of 0.002 to 0.15 per 10,000 clients. HIV-related deaths averted are estimated to be much larger, 19-146 discounted deaths per 10,000 clients. DISCUSSION: While there is some additional short-term risk of SARS-CoV-2 transmission associated with providing HIV services, the risk of additional COVID-19 deaths is at least 100 times less than the HIV deaths averted by those services. Ministries of Health need to take into account many factors in deciding when and how to offer essential health services during the COVID-19 pandemic. This work shows that the benefits of continuing key HIV services are far larger than the risks of additional SARS-CoV-2 transmission.


Subject(s)
COVID-19/transmission , Health Services Accessibility/trends , Health Services/trends , COVID-19/complications , COVID-19/epidemiology , HIV Infections/complications , HIV Infections/epidemiology , HIV Infections/therapy , HIV-1/pathogenicity , Health Services Administration , Humans , Models, Theoretical , Pandemics/prevention & control , Risk Assessment/methods , SARS-CoV-2/pathogenicity
3.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-296783

ABSTRACT

SARS-CoV-2 variant Omicron (B.1.1.529) was classified as a variant of concern (VOC) on November 26, 2021. The infectivity, severity, and immune evasion properties of Omicron relative to the Delta variant will determine 1) the probability of dominant future transmission, and 2) the impact on disease burden. Here we apply an individual-based transmission model to identify thresholds for Omicrons potential dominance, impact on health, and risk to health systems;and identify for which combinations of viral properties, current interventions would be sufficient to control transmission. We show that, with first-generation SARS-CoV-2 vaccines and limited physical distancing in place, the threshold for Omicrons future dominance will primarily be driven by its degree of infectivity. However, Omicrons potential dominance may not necessarily lead to increased public health burden. Expanded vaccination that includes a third-dose for adults and child vaccination strategies is projected to have the biggest public health benefit for a highly infective, highly severe variant with low immune evasion capacity. However, a highly immune evading variant that becomes dominant will likely require alternative measures for control, such as strengthened physical distancing measures, novel treatments, and second-generation vaccines. These findings provide quantitative guidance to decision-makers at a critical time while Omicron properties are being assessed. We emphasize the importance of both genomic and population epidemiological surveillance.

4.
Epidemics ; 38: 100535, 2022 03.
Article in English | MEDLINE | ID: covidwho-1568689

ABSTRACT

BACKGROUND: As vaccination coverage against SARS-CoV-2 increases amidst the emergence and spread of more infectious and potentially more deadly viral variants, decisions on timing and extent of relaxing effective, but unsustainable, non-pharmaceutical interventions (NPIs) need to be made. METHODS: An individual-based transmission model of SARS-CoV-2 dynamics, OpenCOVID, was developed to compare the impact of various vaccination and NPI strategies on the COVID-19 epidemic in Switzerland. OpenCOVID uses the Oxford Containment Health Index (OCHI) to quantify the stringency of NPIs. RESULTS: Even if NPIs in place in March 2021 were to be maintained and the vaccine campaigns rollout rapidly scaled-up, a 'third wave' was predicted. However, we find a cautious phased relaxation can substantially reduce population-level morbidity and mortality. We find that a faster vaccination campaign can offset the size of such a wave, allowing more flexibility for NPIs to be relaxed sooner. Model outcomes were most sensitive to the level of infectiousness of variants of concern observed in Switzerland. CONCLUSION: A rapid vaccination rollout can allow the sooner relaxation of NPIs, however ongoing surveillance of - and swift responses to - emerging viral variants is of utmost importance for epidemic control.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Humans , Switzerland/epidemiology , Vaccination
5.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-295420

ABSTRACT

Background: This modeling study aims to measure the impact COVID-19-related tuberculosis (TB) service disruptions had on key TB outcomes in Indonesia, Kyrgyzstan, Malawi, Mozambique, and Peru, and the mitigation of that impact through catch-up strategies in each country.<br><br>Methods: Quarterly epidemiological estimates and programmatic TB data capturing disruption levels to each TB service were collected by National TB Programmes (NTPs) in 2019, for a pre-COVID-19 baseline, and throughout 2020. These data, together with the NTP’s COVID-19 response plans, were used within Optima TB models to project TB incidence and deaths over five years.<br><br>Findings: Countries reported disruptions of up to 64% to passive TB case finding. TB treatment experienced lower levels of disruption of up to 21%. We predicted that under the worse-case scenario new latent TB infections, new active TB infections, and TB-related deaths could increase by up to 23%, 11%, and 20%, respectively, by 2024. However, three of the five countries were on track to mitigate these increases to 3% or less by maintaining TB services in 2021 and 2022 and by implementing proposed catch-up strategies thereafter. Indonesia was already experiencing the worse-case scenario, which could lead to 270,000 additional active TB infections and 36,000 additional TB-related deaths by the end of 2024.<br><br>Interpretation: The COVID-19 pandemic is projected to negatively affect progress towards 2035 End TB targets, especially in countries already off-track. Findings highlight the need to proactively maintain TB service availability under a range of scenarios, including potential new waves of COVID-19 caused by more transmissible variants.<br><br>Funding Information: UNAIDS<br><br>Declaration of Interests: None to declare.

6.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-295129

ABSTRACT

Background: Reducing unmet need for modern contraception and expanding access to quality maternal health (MH) services are priorities for improving women’s health and economic empowerment including in Small Island Developing States in the Pacific and Caribbean. We estimated health benefits and return-on-investment for contraceptive and MH interventions to help ensure appropriate prioritization.<br><br>Methods: Contraceptive and MH interventions were scaled linearly from 2022 (following COVID-19 disruptions) to reach zero unmet need for modern contraception and 95% MH intervention coverage by 2030. Five Pacific (Kiribati, Samoa, Solomon Islands, Tonga, and Vanuatu) and four Caribbean (Barbados, Guyana, Jamaica, and Saint Lucia) countries were considered based on population survey availability. Health outcomes were estimated and converted to economic benefits, and compared for business-as-usual (BAU) (coverage maintained) and coverage-targets-achieved scenarios.<br><br>Findings: An additional US$13.4M (US$10.9M-US$16.0M) is needed over 2020-2030 for the five Pacific countries to reach coverage targets (19% more than US$70.5M to maintain BAU). This could avert 126,000 (40%) unintended pregnancies, 2,200 (28%) stillbirths, and 121 (29%) maternal deaths and bring an elevenfold economic benefit of US$149.7M (US$54.5M-US$214.7M) by 2040. For the four Caribbean countries, an additional US$18.8M (US$15.3M-US$22.4M) is needed to reach targets (5% more than US$342.3M to maintain BAU). This could avert 127,000 (23%) unintended pregnancies, 3,600 (23%) stillbirths, and 221 (25%) maternal deaths and bring a twentyfold economic benefit of US$375.4M (US$137.9M-US$540.6M) by 2040.<br><br>Interpretation: Achieving full coverage of contraceptive and maternal health services in the Pacific and Caribbean is likely to be affordable and have high return-on-investment.<br><br>Funding Information: Funding for this study was provided by UNFPA.<br><br>Declaration of Interests: None declared.<br>

7.
PLoS Med ; 18(10): e1003831, 2021 10.
Article in English | MEDLINE | ID: covidwho-1477511

ABSTRACT

BACKGROUND: UNAIDS has established new program targets for 2025 to achieve the goal of eliminating AIDS as a public health threat by 2030. This study reports on efforts to use mathematical models to estimate the impact of achieving those targets. METHODS AND FINDINGS: We simulated the impact of achieving the targets at country level using the Goals model, a mathematical simulation model of HIV epidemic dynamics that includes the impact of prevention and treatment interventions. For 77 high-burden countries, we fit the model to surveillance and survey data for 1970 to 2020 and then projected the impact of achieving the targets for the period 2019 to 2030. Results from these 77 countries were extrapolated to produce estimates for 96 others. Goals model results were checked by comparing against projections done with the Optima HIV model and the AIDS Epidemic Model (AEM) for selected countries. We included estimates of the impact of societal enablers (access to justice and law reform, stigma and discrimination elimination, and gender equality) and the impact of Coronavirus Disease 2019 (COVID-19). Results show that achieving the 2025 targets would reduce new annual infections by 83% (71% to 86% across regions) and AIDS-related deaths by 78% (67% to 81% across regions) by 2025 compared to 2010. Lack of progress on societal enablers could endanger these achievements and result in as many as 2.6 million (44%) cumulative additional new HIV infections and 440,000 (54%) more AIDS-related deaths between 2020 and 2030 compared to full achievement of all targets. COVID-19-related disruptions could increase new HIV infections and AIDS-related deaths by 10% in the next 2 years, but targets could still be achieved by 2025. Study limitations include the reliance on self-reports for most data on behaviors, the use of intervention effect sizes from published studies that may overstate intervention impacts outside of controlled study settings, and the use of proxy countries to estimate the impact in countries with fewer than 4,000 annual HIV infections. CONCLUSIONS: The new targets for 2025 build on the progress made since 2010 and represent ambitious short-term goals. Achieving these targets would bring us close to the goals of reducing new HIV infections and AIDS-related deaths by 90% between 2010 and 2030. By 2025, global new infections and AIDS deaths would drop to 4.4 and 3.9 per 100,000 population, and the number of people living with HIV (PLHIV) would be declining. There would be 32 million people on treatment, and they would need continuing support for their lifetime. Incidence for the total global population would be below 0.15% everywhere. The number of PLHIV would start declining by 2023.


Subject(s)
Disease Eradication , Global Health , Goals , HIV Infections/prevention & control , Models, Biological , Models, Theoretical , Public Health , Acquired Immunodeficiency Syndrome/epidemiology , Acquired Immunodeficiency Syndrome/prevention & control , Acquired Immunodeficiency Syndrome/therapy , Adolescent , Adult , COVID-19 , Cause of Death , Epidemics , Female , HIV Infections/epidemiology , HIV Infections/therapy , Humans , Incidence , Male , SARS-CoV-2 , Social Determinants of Health , United Nations , Young Adult
8.
PLoS Comput Biol ; 17(7): e1009149, 2021 07.
Article in English | MEDLINE | ID: covidwho-1325366

ABSTRACT

The COVID-19 pandemic has created an urgent need for models that can project epidemic trends, explore intervention scenarios, and estimate resource needs. Here we describe the methodology of Covasim (COVID-19 Agent-based Simulator), an open-source model developed to help address these questions. Covasim includes country-specific demographic information on age structure and population size; realistic transmission networks in different social layers, including households, schools, workplaces, long-term care facilities, and communities; age-specific disease outcomes; and intrahost viral dynamics, including viral-load-based transmissibility. Covasim also supports an extensive set of interventions, including non-pharmaceutical interventions, such as physical distancing and protective equipment; pharmaceutical interventions, including vaccination; and testing interventions, such as symptomatic and asymptomatic testing, isolation, contact tracing, and quarantine. These interventions can incorporate the effects of delays, loss-to-follow-up, micro-targeting, and other factors. Implemented in pure Python, Covasim has been designed with equal emphasis on performance, ease of use, and flexibility: realistic and highly customized scenarios can be run on a standard laptop in under a minute. In collaboration with local health agencies and policymakers, Covasim has already been applied to examine epidemic dynamics and inform policy decisions in more than a dozen countries in Africa, Asia-Pacific, Europe, and North America.


Subject(s)
COVID-19 , Models, Biological , SARS-CoV-2 , Systems Analysis , Basic Reproduction Number , COVID-19/etiology , COVID-19/prevention & control , COVID-19/transmission , COVID-19 Testing , COVID-19 Vaccines , Computational Biology , Computer Simulation , Contact Tracing , Disease Progression , Hand Disinfection , Host Microbial Interactions , Humans , Masks , Mathematical Concepts , Pandemics , Physical Distancing , Quarantine , Software
9.
Lancet HIV ; 7(9): e629-e640, 2020 09.
Article in English | MEDLINE | ID: covidwho-695906

ABSTRACT

BACKGROUND: The COVID-19 pandemic could lead to disruptions to provision of HIV services for people living with HIV and those at risk of acquiring HIV in sub-Saharan Africa, where UNAIDS estimated that more than two-thirds of the approximately 38 million people living with HIV resided in 2018. We aimed to predict the potential effects of such disruptions on HIV-related deaths and new infections in sub-Saharan Africa. METHODS: In this modelling study, we used five well described models of HIV epidemics (Goals, Optima HIV, HIV Synthesis, an Imperial College London model, and Epidemiological MODeling software [EMOD]) to estimate the effect of various potential disruptions to HIV prevention, testing, and treatment services on HIV-related deaths and new infections in sub-Saharan Africa lasting 6 months over 1 year from April 1, 2020. We considered scenarios in which disruptions affected 20%, 50%, and 100% of the population. FINDINGS: A 6-month interruption of supply of antiretroviral therapy (ART) drugs across 50% of the population of people living with HIV who are on treatment would be expected to lead to a 1·63 times (median across models; range 1·39-1·87) increase in HIV-related deaths over a 1-year period compared with no disruption. In sub-Saharan Africa, this increase amounts to a median excess of HIV deaths, across all model estimates, of 296 000 (range 229 023-420 000) if such a high level of disruption occurred. Interruption of ART would increase mother-to-child transmission of HIV by approximately 1·6 times. Although an interruption in the supply of ART drugs would have the largest impact of any potential disruptions, effects of poorer clinical care due to overstretched health facilities, interruptions of supply of other drugs such as co-trimoxazole, and suspension of HIV testing would all have a substantial effect on population-level mortality (up to a 1·06 times increase in HIV-related deaths over a 1-year period due to disruptions affecting 50% of the population compared with no disruption). Interruption to condom supplies and peer education would make populations more susceptible to increases in HIV incidence, although physical distancing measures could lead to reductions in risky sexual behaviour (up to 1·19 times increase in new HIV infections over a 1-year period if 50% of people are affected). INTERPRETATION: During the COVID-19 pandemic, the primary priority for governments, donors, suppliers, and communities should focus on maintaining uninterrupted supply of ART drugs for people with HIV to avoid additional HIV-related deaths. The provision of other HIV prevention measures is also important to prevent any increase in HIV incidence. FUNDING: Bill & Melinda Gates Foundation.


Subject(s)
Anti-HIV Agents/supply & distribution , Betacoronavirus/pathogenicity , Coronavirus Infections/epidemiology , HIV Infections/epidemiology , Models, Statistical , Pandemics , Pneumonia, Viral/epidemiology , Africa South of the Sahara/epidemiology , Anti-HIV Agents/therapeutic use , Antiretroviral Therapy, Highly Active , COVID-19 , Condoms/supply & distribution , Coronavirus Infections/mortality , Coronavirus Infections/transmission , Coronavirus Infections/virology , Female , Global Health/trends , HIV Infections/mortality , HIV Infections/transmission , HIV Infections/virology , HIV-1/drug effects , HIV-1/growth & development , Humans , Incidence , Infant, Newborn , Infectious Disease Transmission, Vertical/prevention & control , Infectious Disease Transmission, Vertical/statistics & numerical data , Male , Pneumonia, Viral/mortality , Pneumonia, Viral/transmission , Pneumonia, Viral/virology , SARS-CoV-2 , Sexual Behavior/psychology , Sexual Behavior/statistics & numerical data , Survival Analysis
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