Durable Humoral and Cellular Immune Responses Following Ad26.COV2.S Vaccination for COVID-19

Interim immunogenicity and efficacy data for the Ad26.COV2.S vaccine for COVID-19 have recently been reported. We describe here the 8-month durability of humoral and cellular immune responses in 20 individuals who received one or two doses of 5x10^10 vp or 10^11 vp Ad26.COV2.S and in 5 participants who received placebo. We evaluated antibody and T cell responses on day 239, which was 8 months after the single-shot vaccine regimen (N=10) or 6 months after the two-shot vaccine regimen (N=10), although the present study was not powered to compare these regimens. We also report neutralizing antibody responses against the parental SARS-CoV-2 WA1/2020 strain as well as against the SARS-CoV-2 variants D614G, B.1.1.7 (alpha), B.1.617.1 (kappa), B.1.617.2 (delta), P.1 (gamma), B.1.429 (epsilon), and B.1.351 (beta).