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Duration of immunity to virus infections can vary, ranging from lifelong immunity with measles to transient protection to seasonal coronaviruses. Antibody responses to SARS in 2003 remained detectable for around 3 years but T cell responses proved much more durable. Prior infection and vaccination are associated with high levels of protection against re-infection with SARS-CoV-2. Both humoral and T-cell mediated immunity are likely to contribute to protection from infection and disease from COVID-19 as is the case with other respiratory virus infections. Virus neutralizing antibodies correlate with protection from COVID-19 infection and in symptoms.
Findings from this study suggest that neutralizing antibody mediated protection from re-infection against the original strains of SARS-CoV-2 is likely to remain for 700 days or more after symptomatic COVID-19 infection but variants of concern may lead to an erosion, but not abrogation, of this protection.
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