Limited data on antibody responses to SARS-CoV-2 and related coronaviruses suggest that recovery from COVID-19 might confer immunity against reinfection, at least temporarily, according to a viewpoint in JAMA.
Understanding whether and how recovery from COVID-19 confers immunity to, or decreased severity of, reinfection is needed to inform current efforts to safely scale back public health interventions.
Detectable IgM and IgG antibodies develop within days to weeks of symptom onset, although why some patients do not develop a humoral response is uncertain. Another uncertainty is that greater clinical severity leads to greater antibody titres, but does not always correlate with clinical improvement.
Mild symptoms can resolve prior to seroconversion, although detectable antibodies precede viral loads, and titres rise over the subsequent 2-3 weeks. Persistent viral RNA may be detected weeks after recovery, but there is no evidence that patients remain infectious. The absolute duration of viral shedding is unknown.
The durability of neutralising antibodies (NABs) is not defined, but 40 days is described. Although, detection of NABs is not synonymous with durable immunity.
Longitudinal studies with cohorts of people who have recovered from COVID-19 are needed to monitor for signs and symptoms of reinfection.
To date, no reinfections of COVID-19 have been confirmed.