Oxford University explains that delayed second and third doses of AstraZeneca vaccine can actually increase immunity against Covid-19. According to their study, the first and second dose intervals of up to 45 weeks did not compromise immunity.
In addition, based on a study that has not been peer-reviewed, it is said that administering a third dose more than six months after the second dose also leads to a ‘substantial increase’ in antibodies and triggers a ‘strong increase’ in the immune response.
“This should be reassuring news for countries with lower vaccine stocks, who may be concerned about delays in administering a second dose to their populations,” said Oxford trial lead researcher Andrew Pollard.
“There was a good response to the second dose, even 10 months after the first,” he said.
Delaying The Third Dose
The researchers also said the results of the study on delaying the third dose were also positive. This is in response to countries with vaccination programs considering the importance of a third dose to extend immunity.
“It is not known whether additional doses are needed due to reduced immunity or to augment immunity to the new variant of concern,” said senior lead author Teresa Lambe.
AstraZeneca vaccinations are now registered in 160 countries and are appreciated for their relatively low cost and ease of transportation.
A separate study by Oxford also revealed that alternating doses of the AstraZeneca vaccine with that developed by Pfizer/BioNTech also increased the immune response.
Research subjects are said to respond differently depending on the order of administration of vaccine injections, but a vaccination schedule involving AstraZeneca and Pfizer/BioNTech products could potentially be used to provide flexibility in dealing with Covid-19.
Matthew Snape, head of the trial’s research, explained that when the vaccine was mixed and then administered at four-week intervals it would trigger an ‘immune response that is above the threshold set by the standard AstraZeneca vaccine schedule.
