Covid-19 vaccines made by Pfizer and Moderna that use mRNA technology provide the biggest boost to antibody levels when given 10-12 weeks after the second dose, a new British study has found.

The "COV-Boost" study was cited by British officials when they announced that Pfizer and Moderna were preferred for use in the country's booster campaign, but the data has only been made publicly available now.

The study found that...