This is a summary, written by members of the CITF Secretariat, of:

Ma X, Li Z, Whelan M, Kim D, Cao C, Yanes-Lane M, Yan T, Jaenisch T, Chu M, Clifton DA, Subissi L, Bobrovitz N, Arora RK. Serology assays used in SARS-CoV-2 seroprevalence surveys worldwide: a systematic review and meta-analysis of assay features, testing algorithms, and performance. medRxiv. 2022 Oct 15. doi: doi.org/10.1101/2022.10.13.22280957.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members

A systematic review carried out by the CITF-funded SeroTracker team, released in preprint, and not yet peer reviewed, reported that third-party or independent evaluations from manufacturers found that the manufacturers appear to overstate the sensitivity and specificity of their serological assays targeting SARS-CoV-2. This may have an impact on the validity of estimates and impose bias by under- or over-estimating seroprevalence by up to 9.5%.

Key points:

  • Among 1807 serosurveys, 192 unique commercial assays and 380 self-developed assays were identified.
  • According to manufacturer data, 28.6% of all commercial assays met the World Health Organization criteria for emergency use, which requires 90% sensitivity Ability of a test to correctly identify patients with SARS-CoV-2 antibodies and 97% specificity Ability of a test to correctly identify patients without SARS-CoV-2 antibodies.
  • Third-parties indicated that manufacturers overstated the sensitivity and specificity of the serology assays by 5.4% and 2.8%, respectively. Independent group evaluations indicated that manufacturers overstated the sensitivity and specificity of the serology assays by 6.3% and 1.2%, respectively.
  • As seroprevalence estimates are corrected for stated assay performance, simulations helped the team observe that inaccurate sensitivity and specificity statements can bias seroprevalence estimates.

There are a diverse number of serological assays used worldwide and this can impact the interpretation and reliability of seroprevalence estimates. The authors caution against accepting the sensitivity and specificities reported by manufacturers and recommend employing third-party or independently evaluated assays to inform assay properties prior to conducting seroprevalence studies.

The team used search dates of January 1, 2020, to November 19, 2021, for articles found using Medline, EMBASE, and Web of Science preprints on Europe PMC. All SARS-CoV-2 seroprevalence studies in humans which reported a sample size, sampling date and locale, and prevalence estimate were included. In total, 72,799 titles and abstracts and 4,876 full texts were screened and 1,807 serosurveys were used for the final analysis.