Serological evidence of human infection with SARS-CoV-2: a systematic review and meta-analysis

Abstract

Background: A rapidly increasing number of serological surveys for anti-SARS-CoV-2 antibodies have been reported worldwide. A synthesis of this large corpus of data is needed. Purpose: To evaluate the quality of serological studies and provide a global picture of seroprevalence across demographic and occupational groups, and to provide guidance for conducting better serosurveys. Data sources: PubMed, Embase, Web of Science, medRxiv, bioRxiv, SSRN and Wellcome were searched for English-language papers published from December 1, 2019 to August 28, 2020. Study selection: Serological studies that evaluated seroprevalence of SARS-CoV-2 infections in humans. Data extraction: Two investigators independently extracted data from included studies. Data Synthesis: Most of 178 serological studies, representing tests in >800,000 individuals, identified were of low quality. Close contacts and high-risk healthcare workers had higher seroprevalence of 22.9% (95% CI: 11.1-34.7%) and 14.9% (4.8-25.0%), compared to low-risk healthcare workers and general population of 5.5% (4.6-6.4%) and 6.3% (5.5-7.1%). Generally, young people (0-20 yrs) were less likely to be seropositive compared to the middle-aged (21-55 yrs) populations (RR, 0.8, 95% CI: 0.7-0.8). Seroprevalence correlated with clinical COVID-19 reports with 10 (range: 2 to 34) infections per confirmed COVID-19 case. Limitations: Some heterogeneity cannot be well explained quantitatively. Conclusions: The overall quality of seroprevalence studies examined was low. The relatively low seroprevalence among general populations suggest that in most settings, antibody-mediated herd immunity is far from being reached. Given that ratio of infections to confirmed cases is on the same order of magnitude across different locales, reported case numbers may help provide insights into the proportion of the population infected. Primary Funding source: National Science Fund for Distinguished Young Scholars (PROSPERO: CRD42020198253).

A systematic review on the recurrence of SARS-CoV-2 virus: frequency, risk factors, and possible explanations

“…Among the reported patients, eight cases were reported that had experienced recurrence more than once; two times in four patients [ 20 , 58 , 69 ], three times in two patients [ 14 , 50 ], and four times in two patients [ 48 , 62 ]. In a more detailed review of five cases with positive RT-PCR test for repeated times, most of them were asymptomatic or presented mild symptoms [ 14 , 48 , 50 , 58 , 69 ].…”

“…In most of the studies, no significant association between the gender and susceptibility of disease recurrence has been found [ 1 , 13 , 14 , 19 , 20 , 34 ]. Besides, age was not associated with the risk of SARS-CoV-2 recurrence [ 1 , 13 , 14 , 19 , 20 , 34 ], although in a number of studies, some evidence regarding the increased risk among the younger patients has been shown [ 1 , 14 ]. In a study, it has been suggested that patients in some specific age ranges are at the higher risk of recurrence, in this case, 25% of those with disease recurrence were between 20 and 29 years old [ 16 ].…”

Global, regional, and national estimates of target population sizes for covid-19 vaccination: descriptive study

“…Therefore, we collected data on the number of people with covid-19 as of 10 November 2020 and examined serology surveys. We found data on the number of people who tested positive for SARS-CoV-2 by reverse transcription polymerase chain reaction (n=182 countries) or serological assays (n=63) from published literature 6 and official reports (table S4). The number of serologically confirmed cases in a country was estimated as the seroprevalence of SARS-CoV-2 multiplied by the corresponding population size.…”

“…Despite 65.0 million cases reported so far, 2 most of the world population still remains susceptible. Several seroepidemiological studies have reported low seroprevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in the range of 1.0-10.8%, 3 4 5 although higher proportions have been reported locally (eg, approximately 20% in New York City, United States 6 ). Therefore, a large demand for covid-19 vaccines is expected during the next year.…”

The Conundrum of Giglio Island: unraveling the dynamics of an apparent resistance to COVID-19 – A descriptive study

“…There are few comparisons with other studies, because, despite sharing similarities with other seroprevalence investigations, (24) it refers to a small and quasi-segregated population where it was possible to carefully track every case of COVID-19 and the social network of exposed individuals related to it.…”