Durability of neutralizing antibody and T-cell responses in COVID-19 patients after infection and booster vaccination

Determining the durability of immunity after SARS-CoV-2 infection or vaccination is critical for understanding immune protection upon reinfection and optimizing vaccine design. We measured SARS-CoV-2-specific antibodies and T-cell responses in COVID-19 convalescent patients up to 14 months after infection and COVID-19 convalescents who received two doses of BBIBP-CorV at 6-month intervals. We observed that most convalescents had durable neutralizing antibody and T-cell responses against the SARS-CoV-2 Wuhan strain at least 14 months after infection. Administering a booster dose to convalescent patients significantly increased neutralizing antibodies against the Wuhan strain, but neutralization activity against Omicron BA.1, BA.2, BA.2.12.1, and BA.4/BA.5 was significantly decreased. Six months after the first dose vaccination, the neutralizing antibody levels significantly declined and were not further enhanced by a second dose. Omicron BA.1-specific T-cell responses were detectable in most convalescent patients and were not significantly affected by vaccination. These analyses provide insights into the durability of the immune response after infection and hybrid immunization and may be relevant for future vaccine strategies.