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.
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 that it has yet to be peer-reviewed.
The lead investigator of the Oxford trial, Andrew Pollard, said, “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. There is an excellent response to a second dose, even after a 10-month delay from the first.”