A Systematic Review of the Protective Effect of Prior SARS-CoV-2 Infection on Repeat Infection

  1. N. Kojima
  2. N. K. Shrestha
  3. J. D. Klausner

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Abstract

We systematically reviewed studies to estimate the risk of SARS-CoV-2 reinfection among those previously infected with SARS-CoV-2. For this systematic review, we searched scientific publications on PubMed and MedRxiv, a pre-print server, through August 18, 2021. Eligible studies were retrieved on August 18, 2021. The following search term was used on PubMed: (((“Cohort Studies”[Majr]) AND (“COVID-19”[Mesh] OR “SARS-CoV-2”[Mesh])) OR “Reinfection”[Majr]) OR “Reinfection”[Mesh]. The following search term was used on MedRxiv: “Cohort Studies” AND “COVID-19” OR “SARS-CoV-2” AND “Reinfection”. The search terms were broad to encompass all applicable studies. There were no restrictions on the date of publication. Studies that did not describe cohorts with estimates of the risk of SARS-CoV-2 reinfection among those with previous infection were excluded. Studies that included vaccinated participants were either excluded or limited to sub-groups of non-vaccinated individuals. To identify relevant studies with appropriate control groups, we developed the following criteria for studies to be included in the systematic analysis: (1) baseline polymerase chain reaction (PCR) testing, (2) a uninfected comparison group, (3) longitudinal follow-up, (4) a cohort of human participants, i.e. not a case report or case series, and (5) outcome determined by PCR. The review was conducted following PRISMA guidelines. We assessed for selection, information, and analysis bias, per PRISMA guidelines. We identified 1,392 reports. Of those, 10 studies were eligible for our systematic review. The weighted average risk reduction against reinfection was 90.4% with a standard deviation of 7.7% ( p-value: <0.01). Protection against SARS-CoV-2 reinfection was observed for up to 10 months. Studies had potential information, selection, and analysis biases. The protective effect of prior SARS-CoV-2 infection on re-infection is high and similar to the protective effect of vaccination. More research is needed to characterize the duration of protection and the impact of different SARS-CoV-2 variants.

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  1. Version published to 10.1177/01632787211047932
  2. ScreenIT

    SciScore for 10.1101/2021.08.27.21262741: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Ethicsnot detected.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    For this systematic review, we searched scientific publications on PubMed and the pre-print server, MedRxiv. through August 18, 2021.
    PubMed
    suggested: (PubMed, RRID:SCR_004846)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Our study had several limitations. Our review was limited to studies with PCR confirmation of infection and re-infection. Multiple other studies, however, using SARS-CoV-2 antibody status as a measure of infection have similar results (Abu-Raddad et al., 2021; Harvey et al., 2021; A Leidi et al., 2021; A. Leidi et al., 2021). Our systematic review utilized some studies published on MedRxiv, a pre-print server. While MedRxiv had been helpful during the COVID-19 pandemic due to the rapid ability to disseminate information to colleagues, studies that were accessed on the site were not peer-reviewed. Furthermore, many of the studies cannot be replicated because they occurred in settings prior to the availability of vaccination against SARS-CoV-2 among people with history of infection. Many of the studies including in our review followed people infected with SARS-CoV-2 earlier in the pandemic when infection was most likely with the original wildtype strain of SARS-CoV-2 before the development of variant strains. Therefore, our findings may differ in the current context of infections with exposure to variants that differ from the original infecting variant. However a recent pre-print from a study conducted in the United Kingdom found among persons infected during a period of nearly exclusive Delta SARS-CoV-2 transmission, those fully vaccinated with BNT162b2 and ChAd0×1 (had similar levels of protection (82% and 67%, respectively) as those with previous infection (73%) (Pouwels; et...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.08.27.21262741v1 on medRxiv