A third dose of AstraZeneca can boost immunity against variants like Delta

A study from the University of Oxford, published in a preprint in the journal Lancet, reveals that a third dose of the vaccine continues to strengthen antibodies against SARS-CoV-2 against variants. Furthermore, delaying the second injection for up to 10 months does not compromise the immune response.

Third dose of AstraZeneca vs. variants

The first studies published on the effectiveness of the vaccine reveal good immunity, especially after receiving the full regimen. However, this recent work also reveals that injecting a third booster dose causes an increase in antibodies, a potentiation of the T cell response and the immune response against variants.

“It is not known whether booster injections will be needed due to decreased immunity or to increase immunity against variants of concern,” says Associate Professor Teresa Lambe OBE, lead author of these studies. “Here we show that a third dose of ChAdOx1 nCoV-19 (AstraZeneca’s vaccine against the Covid-19 virus) is well tolerated and significantly increases the antibody response. This is very encouraging news, if we find that a further dose is needed.” third dose.”

The side effects of the vaccine itself were also found to be well tolerated, with fewer incidents of side effects after the second and third doses than after the first dose.

Up to 10 month delay of the second dose of AstraZeneca

Another of the conclusions of this research shows that a delay in the administration of the second dose does not compromise the immune response. “By examining the effects of a delay of up to 45 weeks between the first and second doses in study participants, the results demonstrated that antibody levels increased after a delayed second dose,” the university explains in a statement.

“This should be reassuring news for countries with lower vaccine supplies, who may be concerned about delays in getting the second dose to their populations. There is an excellent response to a second shot, even after a delay of 10 months from the first one,” explains Sir Andrew Pollard, Professor of Pediatric Infection and Immunity and Principal Investigator of the vaccine trial at the University of Oxford.