A substantial amount of research evidence suggests that the presence of antibodies following SARS-CoV-2 infection offers some level of immune protection against becoming reinfected with the virus. Immune protection is supported by:
- Reduced number of infections among persons with SARS-CoV-2 antibodies who were studied for 3 months or longer,
- Reduced number of SARS-CoV-2 infections in patients with pre-existing detectable viral antibodies,
- Evidence of viral neutralization in the serum of patients following SARS-CoV-2 infection,
- Vaccination which results in antibody production, reduces the incidence of COVID-19 infection and
- Decreased severity of SARS-CoV-2 infection and prevention of illness after the administration of monoclonal antibody therapy.
Currently, the persistence of antibodies after SARS-CoV-2 infection and the concentration of such antibodies are uncertain. Cohort studies indicate an 80% to 90% reduction in the incidence of COVID infections for at least 6 months after infection among antibody-positive people.26
