A longer interval between the first and second doses of the Pfizer-BioNTech COVID-19 vaccine appears to produce more antibodies, suggest UK researchers.

The findings from a new study support the UKs decision to extend dosing intervals from the initial three weeks gap. An eight-week interval appears to be the sweet spot to tackle the highly transmissible Delta variant.

Investigators compared the immune responses of 503 NHS staff who had been administered their two vaccine doses at different intervals during late last year and early this year, when the Alpha variant, first detected in Kent, was spreading. Antibody levels were measured in the participants’ blood one month after the second dose. The findings revealed that both short and long dosing intervals evoked strong immune responses overall. A three-week interval produced lesser neutralizing antibodies compared to a 10-week interval. 

The longer interval led to fewer T-cells overall but a higher proportion of helper T-cells, which are known to support immune memory… (BBC, July 23, 2021)