Immune response following infection with SARS‐CoV‐2 and other coronaviruses: A rapid review

O Murchu, Eamon; Byrne, Paula; Walsh, Kieran A.; Carty, Paul G.; Connolly, Máire; De Gascun, Cillian; Jordan, Karen; Keoghan, Mary; O'Brien, Kirsty K.; O'Neill, Michelle; Smith, Susan M.; Teljeur, Conor; Ryan, Máirín; Harrington, Patricia

In this review, we systematically searched and summarized the evidence on the immune response and reinfection rate following SARS‐CoV‐2 infection. We also retrieved studies on SARS‐CoV and MERS‐CoV to assess the long‐term duration of antibody responses. A protocol based on Cochrane rapid review methodology was adhered to and databases were searched from 1/1/2000 until 26/5/2020. Of 4744 citations retrieved, 102 studies met our inclusion criteria. Seventy‐four studies were retrieved on SARS‐CoV‐2. While the rate and timing of IgM and IgG seroconversion were inconsistent across studies, most seroconverted for IgG within 2 weeks and 100% (N = 62) within 4 weeks. IgG was still detected at the end of follow‐up (49‐65 days) in all patients (N = 24). Neutralizing antibodies were detected in 92%‐100% of patients (up to 53 days). It is not clear if reinfection with SARS‐CoV‐2 is possible, with studies more suggestive of intermittent detection of residual RNA. Twenty‐five studies were retrieved on SARS‐CoV. In general, SARS‐CoV‐specific IgG was maintained for 1‐2 years post‐infection and declined thereafter, although one study detected IgG up to 12 years post‐infection. Neutralizing antibodies were detected up to 17 years in another study. Three studies on MERS‐CoV reported that IgG may be detected up to 2 years. In conclusion, limited early data suggest that most patients seroconvert for SARS‐CoV‐2‐specific IgG within 2 weeks. While the long‐term duration of antibody responses is unknown, evidence from SARS‐CoV studies suggest SARS‐CoV‐specific IgG is sustained for 1‐2 years and declines thereafter.