Most people who get the first dose of the Pfizer vaccine receive their second shot three weeks later. A new UK study, however, suggests that waiting 12 weeks might be a better option, reports Nature. The study, which has not yet been peer reviewed, looked only at subjects over the age of 80, per Reuters. Researchers found that those who received their booster shot at 12 weeks had roughly three times the antibody response as those who received it at three weeks. The study, done by the University of Birmingham in collaboration with Public Health England, lends support to the UK's controversial decision to delay second doses for 12 weeks in order to make sure more people got the first dose.
“We’ve shown that peak antibody responses after the second Pfizer vaccination are really strongly boosted in older people when this is delayed to 11 to 12 weeks," says the university's Dr. Helen Parry, per the Guardian. "There is a marked difference between these two schedules in terms of antibody responses we see.” The study looked at 175 people over age 80 who received the Pfizer shots. (The study didn't look at any other vaccine.) The results have the potential to affect vaccination protocols, notes Nature, but it's just one more factor for nations to consider. For example, if particularly contagious variants were circulating, that could make people with only one dose more vulnerable. (Read more COVID-19 stories.)