A longer gap between doses of Pfizer’s COVID-19 vaccine leads to higher overall antibody levels than a shorter gap, a British study found on Friday, but there is a sharp drop in antibody levels after the first dose.
The study might help inform vaccination strategies against the Delta variant, which reduces the effectiveness of a first dose of COVID-19 vaccine even though two doses are still protective.
“For the longer dosing interval … neutralising antibody levels against the Delta variant were poorly induced after a single dose, and not maintained during the interval before the second dose,” the authors of the study, which is being led by the University of Oxford, said.
“Following two vaccine doses, neutralising antibody levels were twice as high after the longer dosing interval compared with the shorter dosing interval.” Neutralising antibodies are thought play an important role in immunity against the coronavirus, but not the whole picture, with T cells also playing a part.
