Impact of COVID-19 vaccination on long COVID: a systematic review and meta-analysis (preprint)

Background The impact of COVID-19 vaccination on preventing or treating long COVID is unclear. We aim to assess the impact of COVID vaccinations administered (i) before and (ii) after acute COVID-19, including vaccination after long COVID diagnosis, on the rates or symptoms of long COVID. Methods We searched PubMed, Embase, Cochrane COVID-19 trials, and Europe PMC for preprints from 1 Jan 2020 to 16 Feb 2022. We included trials, cohort, and case control studies reporting on long COVID cases and symptoms with vaccine administration both before and after COVID-19 diagnosis as well as after long COVID diagnosis. Risk of bias was assessed using ROBINS-I. Results We screened 356 articles and found no trials, but 6 observational studies from 3 countries (USA, UK, France) that reported on 442,601 patients. The most common long COVID symptoms studied include fatigue, cough, loss of smell, shortness of breath, loss of taste, headache, muscle ache, trouble sleeping, difficulty concentrating, worry or anxiety, and memory loss or confusion. Four studies reported data on vaccination before SARS-CoV-2 infection, of which three showed statistically significant reduction in long COVID: the odds ratio of developing long COVID with one dose of vaccine ranged between OR 0.22 to 1.03; with two doses OR 0.51 to 1; and with any dose OR 0.85 to 1.01. Three studies reported on post-infection vaccination with odds ratios between 0.38 to 0.91. The high heterogeneity between studies precluded any meaningful meta-analysis. Studies failed to adjust for potential confounders such as other protective behaviours, and missing data, thus increasing the risk of bias, and decreasing the certainty of evidence to low. Discussion Current studies suggest that COVID-19 vaccinations may have protective and therapeutic effects on long COVID. However, more robust comparative observational studies and trials are urgently needed to clearly determine effectiveness of vaccines in prevention and treatment of long COVID.

Impact of the COVID-19 pandemic on surgery for severe endometriosis in the UK: a national database study (preprint)

Objective: To determine the impact of the COVID-19 pandemic on surgery for severe endometriosis in the UK at a national, regional and centre-level. Design: Population-based national cohort study. Population: All women undergoing endometriosis surgery requiring dissection of the pararectal space in the UK from 2017 to 2020 inclusive. Methods: The British Society for Gynaecological Endoscopy (BSGE) collects data nationally on all operations for severe endometriosis which involve dissection of the pararectal space. Annual audits of this database were obtained from the BSGE. Publicly available data on COVID-19 deaths and population were obtained from the UK Office for National Statistics. Main outcome measures: Numbers of annual BSGE-registered endometriosis operations. Results: A total of 5916 operations were performed. The number of operations decreased by 49.4% overall between 2019 and 2020. The number of endometriosis centres remained the same, however the median number of operations per centre decreased from 21 to 12.5, with a median percentage decrease at each centre of 51.0% (IQR 29.4% – 75.0%). There was no significant change in the type of surgery performed. All 11 administrative regions of Great Britain had reduced numbers of BSGE-registered operations in 2020 compared with the average for 2017-2019, with a median 56.6% decrease (range 6.13% - 68.62%). Regional reduction in operations was significantly correlated with COVID-19 death rates (r=0.557, 95% CI of r 0.048 – 1.00, p=0.037). Conclusions: There has been a dramatic fall in the number of operations for severe endometriosis in Britain during the COVID-19 pandemic.

The Effect of Eye Protection on SARS-CoV-2 Transmission: A Systematic Review (preprint)

Background: The effect of eye protection to prevent SARS-CoV-2 infection in the real-world remains uncertain. We aimed to synthesize all available research on the potential impact of eye protection on transmission of SARS-CoV-2. Methods: We searched PROSPERO, PubMed, Embase, The Cochrane Library for clinical trials and comparative observational studies in CENTRAL, and Europe PMC for pre-prints. We included studies that reported sufficient data to estimate the effect of any form of eye protection including face shields and variants, goggles, and glasses, on subsequent confirmed infection with SARS-CoV-2. Results: We screened 898 articles and included 6 reports of 5 observational studies from 4 countries (USA, India, Columbia, and United Kingdom) that tested face shields, goggles, and wraparound eyewear on 7567 healthcare workers. The three before-and-after and one retrospective cohort studies showed statistically significant and substantial reductions in SARS-CoV-2 infections favouring eye protection with odds ratios ranging from 0.04 to 0.6, corresponding to relative risk reductions of 96% to 40%. These reductions were not explained by changes in the community rates. However, the one case-control study reported odds ratio favouring no eye protection (OR 1.7, 95% CI 0.99, 3.0). The high heterogeneity between studies precluded any meaningful meta-analysis. None of the studies adjusted for potential confounders such as other protective behaviours, thus increasing the risk of bias, and decreasing the certainty of evidence to very low. Conclusions: Current studies suggest that eye protection may play a role in prevention of SARS-CoV-2 infection in healthcare workers. However, robust comparative trials are needed to clearly determine effectiveness of eye protections and wearability issues in both healthcare and general populations.

The effect of eye protection on SARS-CoV-2 transmission: a systematic review (preprint)

BackgroundThe effect of eye protection to prevent SARS-CoV-2 infection in the real-world remains uncertain. We aimed to synthesize all available research on the potential impact of eye protection on transmission of SARS-CoV-2. MethodsWe searched PROSPERO, PubMed, Embase, The Cochrane Library for clinical trials and comparative observational studies in CENTRAL, and Europe PMC for pre-prints. We included studies that reported sufficient data to estimate the effect of any form of eye protection including face shields and variants, goggles, and glasses, on subsequent confirmed infection with SARS-CoV-2. FindingsWe screened 898 articles and included 6 reports of 5 observational studies from 4 countries (USA, India, Columbia, and United Kingdom) that tested face shields, googles and wraparound eyewear on 7567 healthcare workers. The three before-and-after and one retrospective cohort studies showed statistically significant and substantial reductions in SARS-CoV-2 infections favouring eye protection with odds ratios ranging from 0.04 to 0.6, corresponding to relative risk reductions of 96% to 40%. These reductions were not explained by changes in the community rates. However, the one case-control study reported odds ratio favouring no eye protection (OR 1.7, 95% CI 0.99, 3.0). The high heterogeneity between studies precluded any meaningful meta-analysis. None of the studies adjusted for potential confounders such as other protective behaviours, thus increasing the risk of bias, and decreasing the certainty of evidence to very low. InterpretationCurrent studies suggest that eye protection may play a role in prevention of SARS-CoV-2 infection in healthcare workers. However, robust comparative trials are needed to clearly determine effectiveness of eye protections and wearability issues in both healthcare and general populations. FundingThere was no funding source for this study. All authors had full access to all data and agreed to final manuscript to be submitted for publication.

Polarization and the Pandemic: American Political Discourse, March – May 2020 (preprint)

By the middle of March, the Democratic primary had effectively ended and the enormity of the Covid-19 pandemic and its human and economic cost began to sink in. The response to the pandemic had already been thoroughly politicized several weeks earlier such that news and information about the pandemic were mediated by political media systems. While the rest of the American media ecosystem focused on describing the pandemic, its economic costs, and criticizing the president for his response, conservative media presented a thoroughly partisan view of events and proactively defended and supported the actions and inactions of the president. For audiences of conservative media, information about the pandemic was communicated not through politically neutral public health authorities but was instead filtered and propagated through media channels shaped by many decades of partisan politics. The mainstream media coverage of the pandemic that got the most attention was highly critical of the president’s response, which may have deepened the politically-rooted differences in perspectives on the pandemic. Compared to conservative media, there was far greater deference among media sources on the center and left to views and perspectives of public health authorities and experts.This report, based on an ecosystem-wide analysis of political media coverage, spans the period of March, April, and May, when the spread and magnitude of the pandemic in the United States became clear, and the response of the government was communicated to the public and debated in the media. In March, coverage of the pandemic dominated political media on both sides of the political spectrum, though significantly less so on the right. The proportion of media attention to the pandemic diminished in April and May on the left. On the right, attention to the pandemic dropped off steeply. In April, conservative media and their audiences devoted substantial attention to coverage of the allegations of sexual harassment by Tara Reade against Joe Biden. In May, there was far more attention in conservative media to relitigating the origins of the Russia investigation under the banner of Obamagate than to the pandemic, which had already exacted a terrible cost and was nowhere near being under control. The collective judgment of the conservative media ecosystem was that this largely unsubstantiated storyline rooted in grievance politics was more deserving of the attention of the American public. For Biden supporters, the drop in attention to Covid-19 was picked up by negative coverage of the Trump administration on other issues. Sanders supporters followed a similar path until the death of George Floyd at the end May took up their attention. This was not replicated in the Biden set. Consistent with our findings in January-February, at the peak of the primaries season, Sanders supporters here too appear more focused on progressive issues, while Biden supporters are largely focused on criticism or rejection of Trump.The basic asymmetric and polarized structure of American political media has changed little over the past several years, and this time period is no exception. The potent role of conservative media in the election victory of Trump in 2016 rested on two distinct factors: first, Trump’s success in securing favorable coverage and strong support in conservative media, and second, the success that conservative media had in influencing media coverage outside of conservative media. The willingness of conservative media and audiences to defend and support Trump is clearly evident during these months. Trump continued to receive strong support in conservative media, which acted to divert, deflect, and reframe negative coverage, despite the rash of negative coverage criticizing the administration’s response to the pandemic. The evidence also points to a further isolation of conservative media in American political discourse and a system less able to shape discourse and coverage outside of its own confines, leaving Americans in more starkly divided epistemic worlds. The administration-friendly narratives about the pandemic and Obamagate got little to no traction outside of conservative media. This finding matches what we found in a prior report in which we describe the inability of conservative media to shape coverage of the Hunter Biden scandal outside of right-wing media during January and February 2020, a pattern that is repeated in October 2020.Neither President Trump nor conservative media have lost their ability to influence the media agenda. For example, in a recent report we describe how Trump was able to create a controversy about mail-in voter fraud that prompted media coverage across the political spectrum. The sexual harassment allegations lodged by Tara Reade against Joe Biden ultimately got a public airing—something conservative media pushed hard on. Despite the fact that the impetus to address this topic came also from the left, the media attention garnered in conservative media was not matched in the center and left. The key difference is that while President Trump and conservative media can still make news, their power to interpret and frame the narrative around key events beyond conservative media is more constrained than in 2016. The asymmetric credibility gap between conservative media and the rest of the media ecosystem appears to have deepened. And professional media seem to succumb less readily to the “bias of balance” problem that had bedeviled much of mainstream coverage of Hillary Clinton’s campaign in 2016.There is plentiful evidence of disinformation in political discourse among partisan media and on social media. The problem is far more acute on the right than the left and considerable attention on the far right is tied to the growing QAnon conspiracy. This development is a troubling symptom of the state of political discourse in the United States and translates into real-world costs. However, the impact of top-down propaganda and disinformation is still a greater problem in the United States, particularly so in relation to Covid-19, as tens of millions of Americans have taken unnecessary risks and helped spread the pandemic because they were misinformed about the dangers of contracting the disease and the value of measures deemed effective by public health authorities in reducing the chance of infection, such as social distancing or mask wearing. Many people, including public health specialists and the general public, have come to the conclusion that compared to the relative successes of other countries in addressing the Covid-19 pandemic, the United States response has been a failure, costing innumerable lives and leaving tens of thousands with long-term health problems, while deepening and extending the economic and social consequences of the pandemic. A large minority of Americans fundamentally disagree with this assessment. These divergent worldviews, the symptom of a larger epistemic crisis in the United States tied to asymmetrically polarized media systems, greatly complicate efforts to effectively meet such collection action challenges, and undermine democratic governance. In this paper, we describe how American media ecosystems are able to sustain such different worldviews and contribute to the mishandling and miscommunication of the pandemic. This report is the second in a series of reports that cover the months running up to the November election.

Partisanship, Impeachment, and the Democratic Primaries: American Political Discourse, January - February 2020 (preprint)

The decisions voters will make at the ballot box on November 3, 2020 will be influenced in no small part by the media coverage of the candidates and issues, including the reporting by journalists, the media personalities and pundits on radio and television, text messages and campaign phone calls, podcasts, political ads, and for many, the incessant flow of social media posts of friends and family. In this report, the first of a series of reports that cover the months running up to the November election, we track political discourse in the United States for January and February of 2020, the period of time just before (Covid-19) began to dominate political discourse. We also describe the longer-term structure of political media ecosystems in the United States that shape public discourse by curating, amplifying, and propagating political stories and narratives to distinct political audiences.The agenda of political media in January and February 2020 centered on the impeachment of the president, the Democratic primaries, and the killing of Qasem Soleimani. This agenda was picked up throughout the media ecosystem, but there were stark differences across the media camps in the framing and narrative contours applied to these topics, presenting radically different depictions of the underlying evidence, facts, and interpretation of events. These differences between media spheres that often extend beyond spin and emphasis reflect and reinforce the depth and strength of the divide in American politics.Mainstream media described in great detail the rationale for impeaching the president, while in right-wing media the ‘call was perfect’ and the impetus for impeachment was a concocted charade, a witch hunt, to illegitimately overturn the 2016 election. Mainstream media described a rash decision by President Trump to order a missile strike on General Soleimani that was then sold to the American public on the false pretenses of a clear and imminent threat of attack against United States embassies. Conservative media hailed the killing as a decisive strike against adversaries that has unquestionably increased American security and standing in the world.While mainstream media coverage devoted similar levels of attention to the Democratic primaries and the impeachment of the president in January, and a majority of their attention to the primary race in February, politically engaged users on social media were more focused on partisan one-upmanship. For Democrats, attention was directed at the impeachment and the missteps of Trump and his administration, and in February, the intervention of Attorney General Barr and the Department of Justice in the sentencing of Roger Stone. Republicans, in turn, focused their attention on time-honored political foes: Nancy Pelosi and the Democratic leadership, Hillary Clinton, and the hostile and biased mainstream media. The patterns of attention on both sides are consistent with a view that negative partisanship plays a dominant role in American politics. Trump supporters on Facebook provided an exception to the pattern of negative coverage where celebratory videos of appearances and events of Trump were popular.Negative polarization spilled over into the Democratic primary race, which came down to a battle between progressives pursuing a platform of aggressive action on healthcare, climate change, and social and economic justice versus those that put regaining the White House above all else and saw a moderate candidate as a better bet. The media coverage promoted by Sanders supporters placed major focus on the candidate and his policy positions. In contrast, Biden supporters were oriented towards negative coverage of Trump. The outcome of the Democratic race is in keeping with the tenet that negative partisanship dominates American politics.Conservatives in America appear to have survived the barrage of negative coverage from mainstream media with their partisan perspectives and belief systems intact. This is not because conservative media erected an impermeable barrier against negative coverage from the center and left. Politically engaged conservatives were informed of the damaging coverage, but were unfailingly offered a reinterpretation and reframing of events and a plausible alternative narrative designed to preempt any second thoughts about allegiance to party and president. In deflecting and reframing negative coverage, the tactics employed by conservative media follow a well-developed pattern: downplay the validity of the story; deflect attention to the other side; attack the integrity and motives of sources; reinforce distrust in media outside of the right wing; and invoke a strong partisan framing to activate political identity.The formidable narrative crafting power of conservative media is employed not as a mechanism for accountability among its participants and leaders and not to police against disinformation and substandard reporting. Instead, it is wielded as a buffer against external influence and against deviance from the party line. This leaves the system vulnerable to misleading and false reporting and to those propagating conspiracies, such as the Gateway Pundit and True Pundit. Hyperpartisan media sources, which thrive on outrage and frequently misinform their audiences, play a prominent role in conservative media. On the left, partisan and hyperpartisan outlets play a much smaller role and less frequently propagate stories unconfirmed by mainstream media. The biggest change we observe in these first two months of 2020 compared to the election cycle of four years ago is the degree to which conservative media activists have shaped mainstream media coverage. In 2016, right-wing media activists succeeded in influencing mainstream coverage of Hillary Clinton, particularly on the unsubstantiated allegations of wrongdoing associated with the Clinton Foundation, which exacerbated and fed upon coverage of her emails and fueled suspicions of corruption and dishonesty. In the current election cycle, conservative media activists rolled out the same playbook that was so successful in 2016. This time, the corruption allegations were focused on Joe Biden, his son Hunter, and their dealings with Ukraine and China. This story was picked up by mainstream media in 2019, but the core allegation—that Joe Biden pressured Ukraine to remove a prosecutor in order to protect his son—fell apart under scrutiny. By January 2020, while conservative media continued to push out exaggerated and false claims, the dominant mainstream framing of this story had shifted to Donald Trump’s abuse of his presidential power for his own political gain, which overshadowed the well-established and misguided actions of Hunter Biden to cash in on his father’s name. The discredited allegations of corrupt dealings by Joe Biden were getting no play in mainstream media. While conservative media continues to exhibit a remarkable capacity for reframing news coverage to align with the beliefs and perceptions of its core audiences, in January and February of 2020, its power to shape mainstream media coverage was diminished compared to 2016. This is the most notable change we observe and has the potential to alter the electoral calculus in the November election.

Pandemic impacts on healthcare utilisation: a systematic review (preprint)

Objectives: To determine the extent and nature of changes in utilisation of healthcare services during COVID-19 pandemic. Design: Systematic review Eligibility: Eligible studies compared utilisation of services during COVID-19 pandemic to at least one comparable period in prior years. Services included visits, admissions, diagnostics, and therapeutics. Studies were excluded if from single-centres or studied only COVID-19 patients. Data sources: PubMed, Embase, Cochrane COVID-19 Study Register, and pre-prints were searched, without language restrictions, until August 10, using detailed searches with key concepts including COVID-19, health services and impact. Data analysis: Risk of bias was assessed by adapting ROBINS-I and Cochrane Effective Practice and Organization of Care tool. Results were analysed using descriptive statistics, graphical figures, and narrative synthesis. Outcome measures: Primary outcome was change in service utilisation between pre-pandemic and pandemic periods. Secondary outcome was the change in proportions of users of healthcare services with milder or more severe illness (e.g. triage scores). Results: 3097 unique references were identified, and 81 studies across 20 countries included, reporting on >11 million services pre-pandemic and 6.9 million during pandemic. For the primary outcome, there were 143 estimates of changes, with a median 37% reduction in services overall (interquartile range -51% to -20%), comprising median reductions for visits of 42%(-53% to -32%), admissions, 28%(-40% to -17%), diagnostics, 31%(-53% to -24%), and for therapeutics, 30%(-57% to -19%). Among 35 studies reporting secondary outcomes, there were 60 estimates, with 27(45%) reporting larger reductions in utilisation among people with a milder spectrum of illness, and 33 (55%) reporting no change. Conclusions: Healthcare utilisation decreased by about a third during the pandemic, with considerable variation, and with greater reductions among people with less severe illness. While addressing unmet need remains a priority, studies of health impacts of reductions may help health-systems prioritise higher-value care in the post-pandemic recovery. Funding, Study registration: No funding was required. PROSPERO: CRD42020203729

Mail-In Voter Fraud: Anatomy of a Disinformation Campaign (preprint)

The claim that election fraud is a major concern with mail-in ballots has become the central threat to election participation during the COVID-19 pandemic and to the legitimacy of the outcome of the election across the political spectrum. President Trump has repeatedly cited his concerns over voter fraud associated with mail-in ballots as a reason that he may not abide by an adverse electoral outcome. Polling conducted in September 2020 suggests that nearly half of Republicans agree with the president that election fraud is a major concern associated with expanded mail-in voting during the pandemic. Few Democrats share that belief. Despite the consensus among independent academic and journalistic investigations that voter fraud is rare and extremely unlikely to determine a national election, tens of millions of Americans believe the opposite. This is a study of the disinformation campaign that led to widespread acceptance of this apparently false belief and to its partisan distribution pattern. Contrary to the focus of most contemporary work on disinformation, our findings suggest that this highly effective disinformation campaign, with potentially profound effects for both participation in and the legitimacy of the 2020 election, was an elite-driven, mass-media led process. Social media played only a secondary and supportive role.Our results are based on analyzing over fifty-five thousand online media stories, five million tweets, and seventy-five thousand posts on public Facebook pages garnering millions of engagements. They are consistent with our findings about the American political media ecosystem from 2015-2018, published in Network Propaganda , in which we found that Fox News and Donald Trump’s own campaign were far more influential in spreading false beliefs than Russian trolls or Facebook clickbait artists. This dynamic appears to be even more pronounced in this election cycle, likely because Donald Trump’s position as president and his leadership of the Republican Party allow him to operate directly through political and media elites, rather than relying on online media as he did when he sought to advance his then-still-insurgent positions in 2015 and the first half of 2016.Our findings here suggest that Donald Trump has perfected the art of harnessing mass media to disseminate and at times reinforce his disinformation campaign by using three core standard practices of professional journalism. These three are: elite institutional focus (if the President says it, it’s news); headline seeking (if it bleeds, it leads); and balance , neutrality, or the avoidance of the appearance of taking a side. He uses the first two in combination to summon coverage at will, and has used them continuously to set the agenda surrounding mail-in voting through a combination of tweets, press conferences, and television interviews on Fox News. He relies on the latter professional practice to keep audiences that are not politically pre-committed and have relatively low political knowledge confused, because it limits the degree to which professional journalists in mass media organizations are willing or able to directly call the voter fraud frame disinformation. The president is, however, not acting alone. Throughout the first six months of the disinformation campaign, the Republican National Committee (RNC) and staff from the Trump campaign appear repeatedly and consistently on message at the same moments, suggesting an institutionalized rather than individual disinformation campaign. The efforts of the president and the Republican Party are supported by the right-wing media ecosystem, primarily Fox News and talk radio functioning in effect as a party press. These reinforce the message, provide the president a platform, and marginalize or attack those Republican leaders or any conservative media personalities who insist that there is no evidence of widespread voter fraud associated with mail-in voting.The primary cure for the elite-driven, mass media communicated information disorder we observe here is unlikely to be more fact checking on Facebook. Instead, it is likely to require more aggressive policing by traditional professional media, the Associated Press, the television networks, and local TV news editors of whether and how they cover Trump’s propaganda efforts, and how they educate their audiences about the disinformation campaign the president and the Republican Party have waged.

Supporting decision-making on allocation of ICU beds and ventilators in pandemics (preprint)

As the world struggles with the COVID-19 pandemic, health service demands have increased to a point where healthcare resources may prove inadequate to meet demand. Guidelines and tools on how to best allocate intensive care beds and ventilators developed during previous epidemics can assist clinicians and policy-makers to make consistent, objective and ethically sounds decisions about resource allocation when healthcare rationing is inevitable. This scoping review of 62 published guidelines, triage protocols, consensus statements and prognostic tools from crisis and non-crisis situations sought to identify a multiplicity of objective factors to inform healthcare rationing of critical care and ventilator care. It also took ethical considerations into account. Prognostic indicators and other decision tools presented here can be combined to create locally-relevant triage algorithms for clinical services and policy makers deciding about allocation of ICU beds and ventilators during a pandemic. Community awareness of the triage protocol is recommended to build trust and alleviate anxiety among the public. This review provides a unique resource and is intended as a discussion starter for clinical services and policy makers to consider formalising an objective triage consensus document that fits the local context. Take-home message An evidence-based catalogue of objective variables from 62 published resources tested in crisis and non-crisis situations can help clinicians make locally relevant triage decisions on ICU and ventilator allocation in inevitable COVID-19 health rationing.

Estimating the seroprevalence of SARS-CoV-2 infections: systematic review (preprint)

Abstract Background: Accurate seroprevalence estimates of SARS-CoV-2 in different populations could help gauge the true magnitude and spread of the infection seroprevalence. Reported estimates have varied greatly, but many have derived from biased samples, and inadequate testing methods. Objective: To estimate the range of valid seroprevalence rates of SARS-CoV-2 in different populations, and compare these seroprevalence estimates with the cumulative cases seen in the same population. Methods: We searched PubMed, Embase, the Cochrane COVID-19 trials, and Europe-PMC for published studies and pre-prints from January 2020 to 25 May 2020 that reported anti-SARS-CoV-2 IgG, IgM and/or IgA antibodies for serosurveys of either the general community or of defined sub-populations, such healthcare workers and other organizations. Results: Of the 837 studies identified, 49 were assessed and 14 were includable. Included studies represented 10 countries and 100,557 subjects: 9 from randomly selected populations, 2 from healthcare workers, 2 from industry populations, and 1of parturient women. The seroprevalence proportions in 10 studies ranged between 1%-10%, and 2 study estimates under 1%, and 2 over 10% - from the notably hard-hit regions of Gangelt in Germany and from Northwest Iran. The two studies in healthcare workers, in Italy and Spain, had seroprevalence rates at higher range of estimates, with the Barcelona hospitals having a higher rate than the Spanish national survey. For only one study was the seroprevalence estimate higher than the cumulative incidence, though these were proximate for several studies. In five studies, the seroprevalence was similar to the cumulative case numbers in the same population. For seropositive cases not previously detected as COVID-19 cases, the majority had prior COVID-like symptoms. Conclusion: The seroprevalence of SARS-CoV-2 mostly less than 10% with the level of infection lower in the general community, suggesting levels well below herd immunity. The similarity of seroprevalence and reported cases is several studies, and high symptom rates in seropositive cases suggest that gaps between seroprevalence rates and reported cases are likely due to undertesting of symptomatic people.

Downsides of face masks and possible mitigation strategies: a systematic review and meta-analysis (preprint)

ObjectiveTo identify, appraise, and synthesise studies evaluating the downsides of wearing facemasks in any setting. We also discuss potential strategies to mitigate these downsides. MethodsPubMed, Embase, CENTRAL, EuropePMC were searched (inception-18/5/2020), and clinical registries were searched via CENTRAL. We also did forward-backward citation search of the included studies. We included randomised controlled trials and observational studies comparing facemask use to any active intervention or to control. Two author pairs independently screened articles for inclusion, extracted data and assessed the quality of included studies. The primary outcomes were compliance, discomforts, harms, and adverse events of wearing facemasks. FindingsWe screened 5471 articles, including 37 (40 references); 11 were meta-analysed. For mask wear adherence, 47% more people wore facemasks in the facemask group compared to control; adherence was significantly higher (26%) in the surgical/medical mask group than in N95/P2 group. The largest number of studies reported on the discomfort and irritation outcome (20-studies); fewest reported on the misuse of masks, and none reported on mask contamination or risk compensation behaviour. Risk of bias was generally high for blinding of participants and personnel and low for attrition and reporting biases. ConclusionThere are insufficient data to quantify all of the adverse effects that might reduce the acceptability, adherence, and effectiveness of face masks. New research on facemasks should assess and report the harms and downsides. Urgent research is also needed on methods and designs to mitigate the downsides of facemask wearing, particularly the assessment of alternatives such as face shields.

Estimating the extent of true asymptomatic COVID-19 and its potential for community transmission: systematic review and meta-analysis (preprint)

BackgroundThe prevalence of true asymptomatic COVID-19 cases is critical to policy makers considering the effectiveness of mitigation measures against the SARS-CoV-2 pandemic. We aimed to synthesize all available research on the asymptomatic rates and transmission rates where possible. MethodsWe searched PubMed, Embase, Cochrane COVID-19 trials, and Europe PMC (which covers pre-print platforms such as MedRxiv). We included primary studies reporting on asymptomatic prevalence where: (a) the sample frame includes at-risk population, and (b) there was sufficiently long follow up to identify pre-symptomatic cases. Meta-analysis used fixed effect and random effects models. We assessed risk of bias by combination of questions adapted from risk of bias tools for prevalence and diagnostic accuracy studies. ResultsWe screened 998 articles and included nine low risk-of-bias studies from six countries that tested 21,035 at-risk people, of which 559 were positive and 83 were asymptomatic. Diagnosis in all studies was confirmed using a RT-qPCR test. The proportion of asymptomatic cases ranged from 4% to 41%. Meta-analysis (fixed effect) found that the proportion of asymptomatic cases was 15% (95% CI: 12% - 18%) overall; higher in non-aged care 16% (13% - 19%), and lower in long-term aged care 8% (3% - 18%). Four studies provided direct evidence of forward transmission of the infection by asymptomatic cases but suggested considerably lower rates than symptomatic cases. DiscussionOur estimates of the prevalence of asymptomatic COVID-19 cases and asymptomatic transmission rates are lower than many highly publicized studies, but still sufficient to warrant policy attention. Further robust epidemiological evidence is urgently needed, including in sub-populations such as children, to better understand the importance of asymptomatic cases for driving spread of the pandemic. FundingOB is supported by NHMRC Grant APP1106452. PG is supported by NHMRC Australian Fellowship grant 1080042. KB was supported by NHMRC Fellowship grant 1174523. All authors had full access to all data and agreed to final manuscript to be submitted for publication. There was no funding source for this study.

Physical interventions to interrupt or reduce the spread of respiratory viruses. Part 1 - Face masks, eye protection and person distancing: systematic review and meta-analysis (preprint)

Abstract OBJECTIVE: To examine the effectiveness of eye protection, face masks, or person distancing on interrupting or reducing the spread of respiratory viruses. DESIGN: Update of a Cochrane review that included a meta-analysis of observational studies during the SARS outbreak of 2003. DATA SOURCES: Eligible trials from the previous review; search of Cochrane Central Register of Controlled Trials, PubMed, Embase and CINAHL from October 2010 up to 1 April 2020; and forward and backward citation analysis. DATA SELECTION: Randomised and cluster-randomised trials of people of any age, testing the use of eye protection, face masks, or person distancing against standard practice, or a similar physical barrier. Outcomes included any acute respiratory illness and its related consequences. DATA EXTRACTION AND ANALYSIS: Six authors independently assessed risk of bias using the Cochrane tool and extracted data. We used a generalised inverse variance method for pooling using a random-effects model and reported results with risk ratios and 95% Confidence Intervals (CI). RESULTS: We included 15 randomised trials investigating the effect of masks (14 trials) in healthcare workers and the general population and of quarantine (1 trial). We found no trials testing eye protection. Compared to no masks there was no reduction of influenza-like illness (ILI) cases (Risk Ratio 0.93, 95%CI 0.83 to 1.05) or influenza (Risk Ratio 0.84, 95%CI 0.61-1.17) for masks in the general population, nor in healthcare workers (Risk Ratio 0.37, 95%CI 0.05 to 2.50). There was no difference between surgical masks and N95 respirators: for ILI (Risk Ratio 0.83, 95%CI 0.63 to 1.08), for influenza (Risk Ratio 1.02, 95%CI 0.73 to 1.43). Harms were poorly reported and limited to discomfort with lower compliance. The only trial testing quarantining workers with household ILI contacts found a reduction in ILI cases, but increased risk of quarantined workers contracting influenza. All trials were conducted during seasonal ILI activity. CONCLUSIONS: Most included trials had poor design, reporting and sparse events. There was insufficient evidence to provide a recommendation on the use of facial barriers without other measures. We found insufficient evidence for a difference between surgical masks and N95 respirators and limited evidence to support effectiveness of quarantine. Based on observational evidence from the previous SARS epidemic included in the previous version of our Cochrane review we recommend the use of masks combined with other measures.