ABSTRACT
ObjectivesUnderstanding persistent cellular and humoral immune responses to SARS-CoV-2 will be of major importance to terminate the ongoing pandemic. Here we assessed long-term immunity in individuals with mild COVID-19 up to one year after a localized SARS-CoV-2 outbreak. MethodsCoNAN was a longitudinal population-based cohort study performed 1.5 months, 6 months and 12 months after a SARS-CoV-2 outbreak in a rural German community. We performed a time series of five different IgG immunoassays assessing SARS-CoV-2 antibody responses on serum samples from individuals that had been tested positive after a SARS-CoV-2 outbreak as well as in control individuals who had a negative PCR result. These analyses were complemented with the determination of spike-antigen specific TH cell responses in the same individuals. ResultsAll infected participants presented as asymptomatic or mild cases. Participants initially tested positive for SARS-CoV-2 infection either with PCR, antibody testing, or both had a rapid initial decline in the serum antibody levels in all serological test but showed a persisting and robust TH cell immunity as assessed by the detection of SARS-CoV-2 specificity of TH cells for up to one year after infection. ConclusionOur data support the notion of a robust T cell immunity in mild and asymptomatic cases of SARS-CoV-2 up to one year after infection. We show that antibody titers decline over one year, but considering several test results, complete seroconversion is rare. Trial RegistrationGerman Clinical Trials Register DRKS00022416. FundingSondervermogen "Corona" of the Thuringian Ministry for Economic Affairs, Science and Digital Society. SV-Kapitel 82 30 Titel 68205 # 5526/32-4-2.
