In the UK, vaccines were initially prioritized to older adults, frontline health and social care workers, and clinically vulnerable individuals, and then offered to other adults in decreasing age order 3. The Pfizer-BioNTech BNT162b2 and Oxford-AstraZeneca ChAdOx1 nCoV-19 (hereafter ChAdOx1) SARS-CoV-2 vaccines have been widely used in the United Kingdom (UK) and worldwide 1, 2. A third booster dose might be needed, prioritized to ChAdOx1 recipients and those more clinically vulnerable. At least 67% protection against infection was estimated to last for 2–3 months after two ChAdOx1 doses, for 5–8 months after two BNT162b2 doses in those without prior infection and for 1–2 years for those unvaccinated after natural infection. Anti-spike IgG levels were associated with protection from infection after vaccination and, to an even greater degree, after prior infection. Prior infection significantly increased antibody peak level and half-life with both vaccines. Older individuals and males had lower peak levels with BNT162b2 but not ChAdOx1, whereas declines were similar across ages and sexes with ChAdOX1 or BNT162b2. After second vaccination, BNT162b2 generated higher peak levels than ChAdOX1. In 222,493 individuals, we found significant boosting of anti-spike IgG by the second doses of both vaccines in all ages and using different dosing intervals, including the 3-week interval for BNT162b2. In this study, we investigated anti-spike IgG antibody responses and correlates of protection after second doses of ChAdOx1 or BNT162b2 vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United Kingdom general population. However, antibody trajectories and the associated duration of protection after a second vaccine dose remain unclear. Antibody responses are an important part of immunity after Coronavirus Disease 2019 (COVID-19) vaccination.

Spike igg antibody test