Delayed doses of AstraZeneca boost immunity: study

Delayed second and third doses of the AstraZeneca vaccine boost immunity against Covid-19, a study by Oxford University, which developed the jab with the British-Swedish firm, said on Monday.

An interval of up to 45 weeks between the first and second dose of the AstraZeneca vaccine led to an enhanced immune response, rather than compromising immunity, the study said.

Giving a third dose of the jab more than six months after the second dose also leads to a “substantial increase” in antibodies and induces a “strong boost” to subjects’ immune response, said the pre-print study, meaning it has yet to be peer-reviewed.

“This should come as reassuring news to countries with lower supplies of the vaccine, who may be concerned about delays in providing second doses to their populations,” said lead investigator of the Oxford trial, Andrew Pollard.

“There is an excellent response to a second dose, even after a 10-month delay from the first.”