Durability of neutralizing antibodies and T-cell response post SARS-CoV-2 infection

The ongoing pandemic of coronavirus disease 19(COVID-19)is caused by a newly discoveredβcoronavirus named severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).How long the adaptive immunity triggered by SARS-CoV-2 can last is of critical clinical relevance in assessing the probability of second infection and efficacy of vaccination.Here we examined,using ELISA,the IgG antibodies in serum specimens collected from 17 COVID-19 patients at 6–7 months after diagnosis and the results were compared to those from cases investigated 2 weeks to 2 months post-infection.All samples were positive for IgGs against the S-and N-proteins of SARS-CoV-2.Notably,14 samples available at 6–7 months post-infection all showed significant neutralizing activities in a pseudovirus assay,with no difference in blocking the cell-entry of the 614D and 614G variants of SARS-CoV-2.Furthermore,in 10 blood samples from cases at 6–7 months post-infection used for memory T-cell tests,we found that interferonγ-producing CD4+and CD8+cells were increased upon SARS-CoV-2 antigen stimulation.Together,these results indicate that durable anti-SARS-CoV-2 immunity is common in convalescent population,and vaccines developed from 614D variant may offer protection from the currently predominant 614D variant of SARS-CoV-2.