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BackgroundThe 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. MethodsWe 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. ResultsWe 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. DiscussionCurrent 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.
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BackgrounRecent observational studies have suggested that vaccines for the omicron variant of SARS-Cov2 may have little or no effect in preventing infection. However, the observed effects may be confounded by patient factors and preventive behaviours or vaccine-related differences in testing behaviour. To assess the potential degree of confounding, we aimed to estimate differences in testing behaviour between unvaccinated and vaccinated populations. MethodsWe recruited 1,526 Australian adults for an online randomised study about COVID testing between October and November 2021, and collected self-reported vaccination status and three measures of COVID-19 testing behaviour. We examined the association between testing intentions and vaccination status in the cross-sectional baseline data of this trial. ResultsOf the 1,526 participants (mean age 31 years): 22% had a COVID-19 test in the past month and 61% ever; 17% were unvaccinated, 11% were partially vaccinated (1 dose), 71% were fully vaccinated (2+ doses). Fully vaccinated participants were twice as likely (RR 2.2; 95% CI 1.8 to 2.8) to report positive COVID testing intentions than those who were unvaccinated (p<.001). Partially vaccinated participants had less positive intentions than those fully vaccinated (p<.001) but higher intentions than those who were unvaccinated (p=.002). DiscussionFor all three measures vaccination predicted greater COVID testing intentions. If the unvaccinated tested at half the rate of the vaccinated, a true vaccine effectiveness of 30% could appear to be a "negative" observed vaccine effectiveness of -40%. Assessing vaccine effectiveness should use methods to account for differential testing behaviours. Test negative designs are currently the preferred option, but its assumptions should be more thoroughly examined.
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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.
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ObjectivePublic cooperation to practice preventive health behaviours is essential to manage the transmission of infectious diseases such as COVID-19. We aimed to investigate beliefs about COVID-19 diagnosis, transmission and prevention that have the potential to impact the uptake of recommended public health strategies. DesignAn online cross-sectional survey conducted May 8 to May 11 2020. ParticipantsA national sample of 1500 Australian adults with representative quotas for age and gender provided by online panel provider. Main outcome measureProportion of participants with correct/incorrect knowledge of COVID-19 preventive behaviours and reasons for misconceptions. ResultsOf the 1802 potential participants contacted, 289 were excluded, 13 declined, and 1500 participated in the survey (response rate 83%). Most participants correctly identified "washing your hands regularly with soap and water" (92%) and "staying at least 1.5m away from others" (90%) could help prevent COVID-19. Over 40% (incorrectly) considered wearing gloves outside of the home would prevent them contracting COVID-19. Views about face masks were divided. Only 66% of participants correctly identified that "regular use of antibiotics" would not prevent COVID-19. Most participants (90%) identified "fever, fatigue and cough" as indicators of COVID-19. However, 42% of participants thought that being unable to "hold your breath for 10 seconds without coughing" was an indicator of having the virus. The most frequently reported sources of COVID-19 information were commercial television channels (56%), the Australian Broadcasting Corporation (43%), and the Australian Government COVID-19 information app (31%). ConclusionsPublic messaging about hand hygiene and physical distancing to prevent transmission appear to have been effective. However, there are clear, identified barriers for many individuals that have the potential to impede uptake or maintenance of these behaviours in the long-term. Currently these non-drug interventions are our only effective strategy to combat this pandemic. Ensuring ongoing adherence to is critical. What is already known on this topicO_LIThe current strategies to prevent the transmission of COVID-19 are behavioural (hand hygiene, physical distancing, quarantining and testing if symptomatic) and rely on the public knowledge and subsequent practice of these strategies. C_LIO_LIPrevious research has demonstrated a good level of public knowledge of COVID-19 symptoms and preventive behaviours but a wide variation in practicing the recommended behaviours. C_LIO_LIAlthough knowledge can facilitate behaviour change, knowledge alone is insufficient to reliably change behaviour to the widespread extent require to combat health crises. C_LI What this study addsO_LIParticipants reveal confusion about whether wearing masks will reduce transmission, apprehension about attending health services, and perceptions that antibiotics and alternative remedies (such as essential oils) prevent transmission. C_LIO_LIAnalysis of why participants hold these beliefs revealed two dominant themes: an incomplete or inaccurate understanding of how COVID-19 is transmitted, and the belief that the behaviours were unnecessary. C_LIO_LIThis study underlines the necessity to not only target public messaging at effective preventative behaviours, but enhance behaviour change by clearly explaining why each behaviour is important. C_LI
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ObjectiveTo compare the effectiveness of hand hygiene using alcohol-based hand sanitiser to soap and water for preventing the transmission of acute respiratory infections (ARIs), and assess the relationship between the dose of hand hygiene and the number of ARI, influenza-like illness (ILI), or influenza events. MethodsSystematic review of randomised trials that compared a community-based hand hygiene intervention (soap and water, or sanitiser) with a control, or trials that compared sanitiser with soap and water, and measured outcomes of ARI, ILI, or laboratory-confirmed influenza or related consequences. Searches were conducted in CENTRAL, PubMed, Embase, CINAHL and trial registries (April 2020) and data extraction completed by independent pairs of reviewers. ResultsEighteen trials were included. When meta-analysed, three trials of soap and water versus control found a non-significant increase in ARI events (Risk Ratio (RR) 1.23, 95%CI 0.78-1.93); six trials of sanitiser versus control found a significant reduction in ARI events (RR 0.80, 95%CI 0.71-0.89). When hand hygiene dose was plotted against ARI relative risk, no clear dose-response relationship was observable. Four trials were head-to-head comparisons of sanitiser and soap and water but too heterogeneous to pool: two found a significantly greater reduction in the sanitiser group compared to the soap group; two found no significant difference between the intervention arms. ConclusionAdequately performed hand hygiene, with either soap or sanitiser, reduces the risk of ARI virus transmission, however direct and indirect evidence suggest sanitiser might be more effective in practice.
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BackgroundAccurate seroprevalence estimates of SARS-CoV-2 in different populations could clarify the extent to which current testing strategies are identifying all active infection, and hence the true magnitude and spread of the infection. Our primary objective was to identify valid seroprevalence studies of SARS-CoV-2 infection and compare their estimates with the reported, and imputed, COVID-19 case rates within the same population at the same time point. MethodsWe searched PubMed, Embase, the Cochrane COVID-19 trials, and Europe-PMC for published studies and pre-prints that reported anti-SARS-CoV-2 IgG, IgM and/or IgA antibodies for serosurveys of the general community from 1 Jan to 12 Aug 2020. ResultsOf the 2199 studies identified, 170 were assessed for full text and 17 studies representing 15 regions and 118,297 subjects were includable. The seroprevalence proportions in 8 studies ranged between 1%-10%, with 5 studies under 1%, and 4 over 10% - from the notably hard-hit regions of Gangelt, Germany; Northwest Iran; Buenos Aires, Argentina; and Stockholm, Sweden. For seropositive cases who were not previously identified as COVID-19 cases, the majority had prior COVID-like symptoms. The estimated seroprevalences ranged from 0.56-717 times greater than the number of reported cumulative cases - half of the studies reported greater than 10 times more SARS-CoV-2 infections than the cumulative number of cases. ConclusionsThe findings show SARS-CoV-2 seroprevalence is well below "herd immunity" in all countries studied. The estimated number of infections, however, were much greater than the number of reported cases and deaths in almost all locations. The majority of seropositive people reported prior COVID-like symptoms, suggesting that undertesting of symptomatic people may be causing a substantial under-ascertainment of SARS-CoV-2 infections. Key messagesO_LISystematic assessment of 17-country data show SARS-CoV-2 seroprevalence is mostly less than 10% - levels well below "herd immunity". C_LIO_LIHigh symptom rates in seropositive cases suggest undertesting of symptomatic people and could explain gaps between seroprevalence rates and reported cases. C_LIO_LIThe estimated number of infections for majority of the studies ranged from 2-717 times greater than the number of reported cases in that region and up to 13 times greater than the cases imputed from number of reported deaths. C_LI
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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.
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BackgroundTimely and effective contact tracing is an essential public health role to curb the transmission of COVID-19. App-based contact tracing has the potential to optimise the resources of overstretched public health departments. However, its efficiency is dependent on wide-spread adoption. We aimed to identify the proportion of people who had downloaded the Australian Government COVIDSafe app and examine the reasons why some did not. MethodAn online national survey with representative quotas for age and gender was conducted between May 8 and May 11 2020. Participants were excluded if they were a healthcare professional or had been tested for COVID-19. ResultsOf the 1802 potential participants contacted, 289 were excluded, 13 declined, and 1500 participated in the survey (response rate 83%). Of survey participants, 37% had downloaded the COVIDSafe app, 19% intended to, 28% refused, and 16% were undecided. Equally proportioned reasons for not downloading the app included privacy (25%) and technical concerns (24%). Other reasons included a belief that social distancing was sufficient and the app is unnecessary (16%), distrust in the Government (11%), and apathy (11%). In addition, COVIDSafe knowledge varied with confusion about its purpose and capabilities. ConclusionFor the COVIDSafe app to be accepted by the public and used correctly, public health messages need to address the concerns of its citizens, specifically in regards to privacy, data storage, and technical capabilities. Understanding the specific barriers preventing the uptake of tracing apps provides the opportunity to design targeted communication strategies aimed at strengthening public health initiatives such as download and correct use.
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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.
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OBJECTIVETo examine the effectiveness of eye protection, face masks, or person distancing on interrupting or reducing the spread of respiratory viruses. DESIGNUpdate of a Cochrane review that included a meta-analysis of observational studies during the SARS outbreak of 2003. DATA SOURCESEligible 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 forwardand backward citation analysis. DATA SELECTIONRandomised and cluster-randomised trials of people of any age, testing the use ofeye 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 ANALYSISSix 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). RESULTSWe 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. CONCLUSIONSMost 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.
