biostudies-literatureUnknown12(1)Amirthalingam GThe UK prioritised delivery of the first dose of BNT162b2 (Pfizer/BioNTech) and AZD1222 (AstraZeneca) vaccines by extending the interval between doses up to 12 weeks. In 750 participants aged 50-89 years, we here compare serological responses after BNT162b2 and AZD1222 vaccination with varying dose intervals, and evaluate these against real-world national vaccine effectiveness (VE) estimates against COVID-19 in England. We show that antibody levels 14-35 days after dose two are higher in BNT162b2 recipients with an extended vaccine interval (65-84 days) compared with those vaccinated with a standard (19-29 days) interval. Following the extended schedule, antibody levels were 6-fold higher at 14-35 days post dose 2 for BNT162b2 than AZD1222. For both vaccines, VE was higher across all age-gNature communications7217https://www.ebi.ac.uk/biostudies/studies/S-EPMC8664823biostudies-literatureSerological responses and vaccine effectiveness for extended COVID-19 vaccine schedules in England.PMC8664823Moss PLadhani SNTessier EBernal JLLinley EWarrener LStowe JBaawuah FO'Brien MWhitaker HAndrews NJSubbarao SWhillock CBrown KEIreland GRamsay MEAmirthalingam GGower CfalseSerological responses and vaccine effectiveness for extended COVID-19 vaccine schedules in England.The UK prioritised delivery of the first dose of BNT162b2 (Pfizer/BioNTech) and AZD1222 (AstraZeneca) vaccines by extending the interval between doses up to 12 weeks. In 750 participants aged 50-89 years, we here compare serological responses after BNT162b2 and AZD1222 vaccination with varying dose intervals, and evaluate these against real-world national vaccine effectiveness (VE) estimates against COVID-19 in England. We show that antibody levels 14-35 days after dose two are higher in BNT162b2 recipients with an extended vaccine interval (65-84 days) compared with those vaccinated with a standard (19-29 days) interval. Following the extended schedule, antibody levels were 6-fold higher at 14-35 days post dose 2 for BNT162b2 than AZD1222. For both vaccines, VE was higher across all age-g2021-01-01T00:00:00Z2021 Dec2025-04-05T16:09:52.452Z2025-04-05T16:09:52.452ZS-EPMC86648233489361110.1038/s41467-021-27410-5