Antibody Response After SARS-CoV-2 Infection and Implications for Immunity : A Rapid Living Review

Abstract

Background: The clinical significance of the antibody response after SARS-CoV-2 infection remains unclear.

Purpose: To synthesize evidence on the prevalence, levels, and durability of detectable antibodies after SARS-CoV-2 infection and whether antibodies to SARS-CoV-2 confer natural immunity.

Data sources: MEDLINE (Ovid), Embase, CINAHL, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, World Health Organization global literature database, and Covid19reviews.org from 1 January through 15 December 2020, limited to peer-reviewed publications available in English.

Study selection: Primary studies characterizing the prevalence, levels, and duration of antibodies in adults with SARS-CoV-2 infection confirmed by reverse transcriptase polymerase chain reaction (RT-PCR); reinfection incidence; and unintended consequences of antibody testing.

Data extraction: Two investigators sequentially extracted study data and rated quality.

Data synthesis: Moderate-strength evidence suggests that most adults develop detectable levels of IgM and IgG antibodies after infection with SARS-CoV-2 and that IgG levels peak approximately 25 days after symptom onset and may remain detectable for at least 120 days. Moderate-strength evidence suggests that IgM levels peak at approximately 20 days and then decline. Low-strength evidence suggests that most adults generate neutralizing antibodies, which may persist for several months like IgG. Low-strength evidence also suggests that older age, greater disease severity, and presence of symptoms may be associated with higher antibody levels. Some adults do not develop antibodies after SARS-CoV-2 infection for reasons that are unclear.

Limitations: Most studies were small and had methodological limitations; studies used immunoassays of variable accuracy.

Conclusion: Most adults with SARS-CoV-2 infection confirmed by RT-PCR develop antibodies. Levels of IgM peak early in the disease course and then decline, whereas IgG peaks later and may remain detectable for at least 120 days.

Primary funding source: Agency for Healthcare Research and Quality. (PROSPERO: CRD42020207098).

Figure 1.. Evidence search and selection.

CCRCT = Cochrane Central Register of Controlled Trials; EUA = emergency use authorization; WHO = World Health Organization. * Exclusion applied to update search only.

Figure 2.. IgM prevalence at 0–30 d and after 30 d.

Studies represented had well-characterized patient populations and settings, measured antibodies using validated immunoassays, and lacked serious methodological problems. RT-PCR = reverse transcriptase polymerase chain reaction. * Number of days from positive result on RT-PCR is minimum of unbounded range (e.g., >20 d). † Study provided mean or median number of days from positive result on RT-PCR.

Figure 3.. IgG prevalence at 0–30 d and after 30 d.

Studies represented had well-characterized patient populations and settings, measured antibodies using validated immunoassays, and lacked serious methodological problems. RT-PCR = reverse transcriptase polymerase chain reaction. * Number of days from positive result on RT-PCR is minimum of unbounded range (e.g., >20 d). † Study provided mean or median number of days from positive result on RT-PCR.