Background: There is very little known about SARS-CoV-2 vaccine immune responses in New Zealand populations at greatest risk for serious COVID-19 disease. Methods: This prospective cohort study assessed immunogenicity in BNT162b2 mRNA vaccine recipients in New Zealand without previous COVID-19, with enrichment for M[a]ori, Pacific peoples, older adults [≥] 65 years of age, and those with co-morbidities. Serum samples were analysed at baseline and 28 days after second dose for presence of quantitative anti-S IgG by chemiluminescent microparticle immunoassay and for neutralizing capacity against Wuhan, Beta, Delta, and Omicron BA.1 strains using a surrogate viral neutralisation assay. Results: 285 adults with median age of 52 years were included. 55% were female, 30% M[a]ori, 28% Pacific peoples, and 26% [≥] 65 years of age. Obesity, cardiac and pulmonary disease and diabetes were more common than the general population. All participants received 2 doses of BNT162b2 vaccine. At 28 days after second vaccination, 99.6% had a sero-response to the vaccine, and anti-S IgG and neutralising antibody levels were high across gender and ethnic groups. IgG and neutralising responses declined with age. Lower responses were associated with age [≥]75 and diabetes, but not BMI. The ability to neutralise the Omicron BA.1 variant in vitro was severely diminished but maintained against other variants of concern. Conclusions: Vaccine antibody responses to BNT162b2 were generally robust and consistent with international data in this COVID-19 naive cohort with representation of key populations at risk for COVID-19 morbidity. Subsequent data on response to boosters, durability of responses and cellular immune responses should be assessed with attention to elderly adults and diabetics.
Immunogenicity of BNT162b2 COVID-19 vaccine in New Zealand adults