key: cord-0754028-ox7js04j
authors: Franceschi, V. B.; Santos, A. S.; Glaeser, A. B.; Paiz, J. C.; Caldana, G. D.; Lessa, C. L. M.; Mayer, A. d. M.; Kuchle, J. G.; Zen, P. R. G.; Vigo, A.; Winck, A. T.; Rotta, L. N.; Thompson, C. E.
title: Population-based prevalence surveys during the COVID-19 pandemic: a systematic review
date: 2020-10-22
journal: nan
DOI: 10.1101/2020.10.20.20216259
sha: 62e66e39c3b418e1756c9610043adaaff7c087fd
doc_id: 754028
cord_uid: ox7js04j

Population-based prevalence surveys of COVID-19 contribute to establish the burden and epidemiology of infection, the role of asymptomatic and mild infections in transmission, and allow more precise decisions about reopen policies. We performed a systematic review to evaluate qualitative aspects of these studies, their reliability, and biases. The available data described 37 surveys from 19 countries, mostly from Europe and America and using antibody testing. They reached highly heterogeneous sample sizes and prevalence estimates. Disproportional prevalence was observed in minority communities. Important risk of bias was detected in four domains: sample size, data analysis with sufficient coverage, measurements in standard way, and response rate. The correspondence analysis showed few consistent patterns for high risk of bias. Intermediate risk of bias was related to American and European studies, blood samples and prevalence >1%. Low risk of bias was related to Asian studies, RT-PCR tests and prevalence <1%.

In December 2019, the third most important coronavirus in the twenty-first century 62 (SARS-CoV-2) was identified as the causative agent of severe acute respiratory syndrome 63 outbreak in Wuhan, Hubei province, China (1,2). The illness named COVID-19 spread rapidly 64 around the world, acquiring pandemic status on March 11, 2020 (3). As of 14 October, 2020, 65 there are ~38 million confirmed cases and ~1.1 million reported deaths in 216 countries, areas 66 or territories. More than 50% of these cases were reported in the USA, India and Brazil, the 67 worst-hit countries (4,5). 68 According to the current evidence, the main form of SARS-CoV-2 spreading is through 69 human-to-human transmission via respiratory droplets and contact routes (6). The standard 70 diagnostic testing method is the Real-Time reverse transcription-PCR (RT-PCR) test (7,8), 71 which is able to detect current infections and it is recommended for people with COVID-19 72 symptoms and for all close contacts of the confirmed cases. A complementary approach is to 73 use antibody tests (e. g. point-of-care test or enzyme linked immunosorbent assay) to detect a 74 past infection and the production of antibodies (IgM and/or IgG) against SARS-CoV-2 (8). 75 COVID-19 causes diverse degrees of illness, ranging from asymptomatic infection to 76 severe pneumonia (9). However, surveillance is only based on the confirmed cases, which can 77 represent an underestimation of total cases due to non-testing in mildly affected or is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. indicated that the use of existing point-of-care serological tests is not supported by available 90 evidence due to low performance (14). Thus, a critical evaluation of these parameters is 91 necessary to verify the reliability of the population-based surveys of COVID-19. 92 We performed a systematic review to evaluate and summarize the main results regarding 93 the COVID-19 prevalence obtained through population-based surveys, their reliability and 94 biases. Our main aims were to evaluate the qualitative aspects of these studies and to compile 95 methodology practices that can influence positively or negatively the prevalence estimates.

The protocol for this systematic review was registered on PROSPERO 99 (CRD42020202186) and it is available in full on Appendix 1. Reporting was conducted Medica dataBASE (EMBASE), bioRxiv, and medRxiv databases were searched using the 106 following controlled vocabulary heading and terms: "seroprevalence", "prevalence", 107 "serology", "immunoassay", "enzyme linked immunosorbent assay", "real time polymerase 108 . CC-BY-NC-ND 4.0 International license It is made available under a perpetuity.

is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint 6 chain reaction", "cross-sectional study", "population screening", "severe acute respiratory 109 syndrome coronavirus 2", "COVID-19". These terms and their synonyms were combined using 110 logical operators and adapted according to the searched database. Only articles published in 111 English were retrieved. The complete search strategy for each database is on Appendix 2, Table   112 1.

The review included cross-sectional or repeated cross-sectional studies using molecular 115 or serological tests to estimate the prevalence of COVID-19 in municipalities, regions, states or 116 countries around the world. Studies were excluded based on the following criteria: (i) non-117 cross-sectional studies, (ii) studies with correlation between COVID-19 and other diseases or 118 health determinants, (iii) non-random selection of participants (e. g. convenience sampling),

(iv) inclusion of a specific group of participants only (e. g., with comorbidities, pregnant, 120 elderly, healthcare workers, pediatric patients), and (v) non-human samples.

Four pairs of authors (AMM and CLML, ABG and JGK, ASS and VBF, GDC and JCP) 123 independently reviewed the titles and abstracts, in parallel, and included publications identified 124 by either author for full-text review. These authors also reviewed full texts to determine which 125 publications met the inclusion criteria and then re-analyzed the texts and supplemental materials 126 to extract the following relevant information, when available: (i) authors, (ii) study location, 127 (iii) coverage, (iv) study type, (v) random sampling method, (vi) period of testing, (vii) number 128 of tests, (viii) biological samples, (ix) type of test used, (x) if test validation was performed, (xi) 129 the test sensitivity and specificity, (xii) prevalence, and (xiii) statistical methods (Table) . is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint Survey Quality 133 We assessed each survey quality by using the Joanna Briggs Institute (JBI) Critical "no" and "unclear" options were selected, meaning "low", "high" and "unclear" risk of bias, 139 respectively. The number of "yes" answers to these nine domains was counted, with a higher Additional objective criteria were adopted for the survey quality assessment. For D4, 144 the prevalence estimates should be stratified by conventional sex and age classes minimally.

For D5, "no" was chosen when there was a lack of a subgroup representativity. If the response 146 rate >70% or <70% with adequate sample size, "yes" was chosen. The option "unclear" was 147 selected only if there was no information about the response rate in the article. For D6, a method 148 was considered valid if the sensitivity >70%. For D7, self-sampling was considered as a practice 149 of high risk of bias. In the case of a collection described by health professionals or trained 150 individuals and using standardized methods, we assumed a low risk of bias. For D8, a minimum 151 description of statistical methods was sufficient to classify the study as low risk of bias. For D9, 152 if the response rate <70% without stratification or statistical management, the study was is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. 

Of 49 full-text articles screened, we excluded 12 (Appendix 2, Table 2 is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint total, 19 countries had studies included in this analysis ( Figure 2 ). Considering the coverage of 181 these studies, 16 (43.2%) had regional (state / province / county) scope, 13 (35.1%) were 182 restricted to municipalities, and 8 (21.6%) were nationwide studies.

The vast majority of studies (n=25; 67.6%) reported only antibody testing, while the is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. Studies that performed molecular tests on naso-and oropharyngeal swabs (NPS) tended 211 to have a low risk of bias, while those with blood samples were related to intermediate risk.

Regarding prevalence, the majority of the studies with swab samples (RT-PCR) showed 213 prevalence (P) <1%, while studies using only blood, or swab and blood, exhibited P>1%. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint being considered nationwide, the sample size was 1,366, which represented ~7x less than 229 necessary (10,179) (56) and there was no management of the low response rate (<50%). Some 230 authors seem to have not been concerned with managing this issue because even though the 231 response rate was low, there was still an adequate sample (23,35,36,40,42) . Repeated cross-232 sectional studies featured a widely distinct prevalence estimate on each round (29,36,49,50) .

This trend might be caused by the ascending curve of infected people, following the epidemic's 234 natural course. Therefore, there was a need for different sample sizes for each period.

Unfortunately, some studies did not yield adequate sample size in all rounds (49, 50). 236 The same proportion of studies validated their methods internally to report accuracy is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. In the study from Stockholm (34), it was observed a significant difference in 289 seroprevalence between the two areas (4.1% in middle-high income and 30% in lower income 290 suburb). The authors related this high prevalence with cramped accommodation, which 291 enhances cluster transmission, and with a majority of public-facing workers in the suburb. In 292 Mumbai (18), the authors found a higher seroprevalence in the slums (54.1%) compared with 293 non-slums (16.1%). Thus, it is discussed that the epidemic may be in advanced stages in slums 294 due to higher population density.

The data from Brazilian studies (46-52) suggest that pandemic were highly It is important to note that the data presented here are based on the articles until 301 September 5, 2020. Therefore, more recent articles are not included in the analysis. In addition, 302 previous pre-print articles can be currently published. In general, we believe that the peer review is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint 14 process should contribute to increase the quality of these currently unpublished articles with a 304 higher risk of bias. 305 We have decided not to conduct a meta-analysis because of the prevalence heterogeneity 306 among studies and the different stages of pandemic faced in the countries and continents at the 307 time of each survey. Thus, a summary measure of meta-analysis would not be able to generalize 308 overall findings sufficiently. In contrast, we found that a correspondence analysis was more 309 able to detect the correlation among variables. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

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POP): a population-based study

Seroprevalence of SARS-CoV-2-Specific Antibodies Among Adults in Los Angeles County

Seroprevalence of SARS-CoV-2-Specific IgG Antibodies Among Adults Living in Connecticut 468

Estimated community seroprevalence of SARS-CoV-2 antibodies-two Georgia counties

High Community SARS-CoV-2

Population point prevalence of SARS-CoV-2 infection based on a statewide random 481 sample-Indiana

Racial 484 and workplace disparities in seroprevalence of SARS-CoV-2 in

COVID-19 Seroprevalence in Baixada Santista Metropolitan Area

Best practices for survey research reports: a synopsis 524 for authors and reviewers

Effect of 526 recruitment methods on response rate in a web-based study for primary care physicians: 527 factorial randomized controlled trial

A meta-analysis of response rates in web-or internet-based 530 surveys

Practical issues in calculating the sample size for prevalence 533 studies

Real-time RT-PCR in COVID-19 detection: issues affecting the 535 results

IgG antibodies to SARS-coronavirus in asymptomatic or subclinical population groups

Seroprevalence of MERS-CoV in healthy adults in western Saudi Arabia

COVID-19: Unique public health 544 issues facing Black, Asian and minority ethnic communities

Assessing differential 547 impacts of COVID-19 on Black communities

It is made available under a perpetuity.is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint It is made available under a perpetuity.is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprintThe copyright holder for this this version posted October 22, 2020. ; https://doi.org/10.1101/2020.10.20.20216259 doi: medRxiv preprint