Immune response memory in patients after one year of COVID-19 infection

April 2022 Covid-19 Nalinee Pathak

A recent study reports that SARS-CoV-2 specific neutralising antibody and T-cell responses were retained after one year of CoVID- infection. These findings were published in the reputed journal Journal Lancet microbe.

The immune system memory is crucial for preventing reinfection or complications due to COVID after initial infection. However, humoral and T-cell response’s robustness remains unknown post one year in patients that have recovered from initial COVID illness.

Study design

The longitudinal study recruited 1096 patients that recovered from COVID-19 and were discharged from the Wuhan Research Center for Communicable Disease Diagnosis and Treatment at the Chinese Academy of Medical Sciences, Wuhan, China, between Jan 7 and May 29, 2020. The participants were asked for a follow-up visit between Dec 16, 2020, and Jan 27, 2021. Immune memory post-Covid infection was characterised by analysing antibodies (IgM, IgA and IgG) against SARS-CoV-2 nucleoprotein, spike protein and the receptor-binding domain. Further, neutralising antibodies against different COVID strains were analysed using a micro-neutralisation assay. Finally, T-cell response and tumour necrosis factor α [TNFα]) were analysed by age and disease severity along with antibody titers.


The majority (90%) of patients had memory T-cell responses indicating COVID-specific T-cell responses. Additionally, seropositivity for antibodies such as N-IgG, S-IgG, and RBD-IgG was 82, 95.2 and 94.2%, respectively. The plasma of recovered individuals showed neutralizing antibodies against SARS-CoV-2 wild-type strain (82%), and D614G (48%), Beta(23%), and Delta variants (49%), respectively indicating higher levels of neutralizing antibodies in wild type strains of COVID than the mutant strain.


The longitudinal study clearly shows that neutralizing antibodies and the T-cell response were there in patients who had been infected with COVID before 12 months. 


Guo, L. et al. (2022) “SARS-CoV-2-specific antibody and T-cell responses 1 year after infection in people recovered from COVID-19: a longitudinal cohort study”, The Lancet Microbe