Lessons from a rapid systematic review of early SARS-CoV-2 serosurveys

Abstract

Background. As the world grapples with the COVID-19 pandemic, there is increasing global interest in the role of serological testing for population monitoring and to inform public policy. However, limitations in serological study designs and test standards raise concerns about the validity of seroprevalence estimates and their utility in decision-making. There is now a critical window of opportunity to learn from early SARS-CoV-2 serology studies. We aimed to synthesize the results of SARS-CoV-2 serosurveillance projects from around the world and provide recommendations to improve the coordination, strategy, and methodology of future serosurveillance efforts.Methods. This was a rapid systematic review of cross-sectional and cohort studies reporting seroprevalence outcomes for SARS-CoV 2. We included completed, ongoing, and proposed serosurveys. The search included electronic databases (PubMed, MedRXIV, BioRXIV, and WHO ICTPR); five medical journals (NEJM, BMJ, JAMA, The Lancet, Annals of Internal Medicine); reports by governments, NGOs, and health systems; and media reports (Google News) from December 1, 2019 to May 1, 2020. We extracted data on study characteristics and critically appraised prevalence estimates using Joanna Briggs Institute criteria.Results. Seventy records met inclusion criteria, describing 73 studies. Of these, 23 reported prevalence estimates: eight preprints, 14 news articles, and one government report. These studies had a total sample size of 35,784 and reported 42 prevalence estimates. Seroprevalence estimates ranged from 0.4% to 59.3%. No estimates were found to have a low risk of bias (43% high risk, 21% moderate risk, 36% unclear). Fifty records reported characteristics of ongoing or proposed serosurveys. Overall, twenty countries have completed, ongoing, or proposed serosurveys. Discussion.Study design, quality, and prevalence estimates of early SARS-CoV2 serosurveys are heterogeneous, suggesting that the urgency to examine seroprevalence may have compromised methodological rigour. Based on the limitations of included studies, future serosurvey investigators and stakeholders should ensure that: i) serological tests used undergo high-quality independent evaluations that include cross-reactivity; ii) all reports of serosurvey results, including media, describe the test used, sample size, and sampling method; and iii) initiatives are coordinated to prevent test fatigue, minimize redundant efforts, and encourage better study methodology.

COVID‐19 diagnostic testing: Technology perspective

“…A universal standard is critical in generating consistent tests by different manufacturers and enables laboratories worldwide to compare results easily. 11,56,82 For example, there are at least seven versions of PCR primers used in SARS-CoV-2 nucleic acid testing (Table 3). 11,83 The US Centers for Disease Control (CDC) recommend primers 54 To address this issue, WHO, FIND, and other research laboratories are collaborating with each other or working independently to evaluate the performance of different diagnostic tests across the world.…”

SARS-CoV-2 Seroprevalence Studies: A Rapid Review

“…This rapid review summarizes the methods, sampling frames, results, and potential sources of bias of the subnational, national, and international serology studies that have been used to estimate the seroprevalence of SARS-CoV-2. Our review builds on a previously published seroprevalence review (19) by using a more comprehensive search strategy that identi ed more published studies, as well as pre-prints and ongoing studies. In accordance with prior work, (19) we found substantial diversity in seroprevalence study characteristics, including their sampling frames, assay sensitivity and speci city, and study locations.…”

“…Our review builds on a previously published seroprevalence review (19) by using a more comprehensive search strategy that identi ed more published studies, as well as pre-prints and ongoing studies. In accordance with prior work, (19) we found substantial diversity in seroprevalence study characteristics, including their sampling frames, assay sensitivity and speci city, and study locations. For example, most studies (n = 20, 77%) derived seroprevalence estimates from a single sampling frame, such as healthcare workers or close contacts of patients with RT-PCR-con rmed COVID-19.…”

“…SARS-CoV-2 seroconversion has been estimated to occur around 13 days after symptom onset, and unlike most other viral antibody responses, IgM and IgG titers to SARS-CoV-2 may be produced nearly simultaneously. (3) , (4) A reliable estimate of community-level seroprevalence of SARS-CoV-2, including among key subgroups such as healthcare workers and other essential workers, is necessary to de ne the true burden of COVID- 19. These data are also needed to de ne the SARS-CoV-2 infection fatality rate, which has been widely debated, by identifying individuals with asymptomatic or minimally symptomatic infection who are less likely to receive RT-PCR testing.…”

Estimating the Percentage of a Population Infected with SARS-CoV-2 Using the Number of Reported Deaths: A Policy Planning Tool

“…However, sero-surveys have some limitations. Sero-surveys can yield biased results if not carefully undertaken [ 14 , 15 ]. This can occur through non-representative sampling of the total population (e.g., blood donors, residual samples from clinical labs), or self-selection among intended random samples (e.g., over-participation of those who suspect they had Covid19) [ 12 , 16 ].…”