A third injection of the Oxford / AstraZeneca vaccine could be an effective booster without the need for adjustments, research suggests.
An Oxford University study found that giving people a third dose more than six months after the second led to a substantial rise in antibodies and increased the body’s ability to fight the coronavirus, including its variants. .
Professor Sir Andrew Pollard, director of the Oxford Vaccine Group, said it was not yet known whether people would need a booster shot in the fall, but new data showed the existing vaccine could be effective.
He said that real-world data from Public Health England (PHE) had already shown that two doses offered good protection against hospital admission and death from the Alpha and Delta variants.
The same study showed that Oxford / AstraZeneca vaccine-induced coronavirus antibodies remain elevated for at least a year after the first dose, in a boost for countries where vaccine supplies are limited and authorities are struggling to keep up. day with their vaccine deployments.
The data, presented in a paper that has not yet been peer-reviewed, shows that although antibody levels erode with a longer gap between the first and second doses, they remain above baseline. The data also show that a prolonged interval of up to 45 weeks between the first and second doses can be beneficial, resulting in a significantly higher antibody response after the second dose.
The recommended gap is four to 12 weeks, depending on geography, but vaccine supply problems have resulted in some people not receiving the vaccine in this period of time.)
Although antibody levels alone do not predict vaccine efficacy, they are a key component of our immune response.
Previous research has shown Protection against symptomatic Covid is maintained after a single dose for at least three months., despite a certain decrease in antibody levels. Therefore, these new data, based on a small group of 30 participants who received late doses, provide further reassurance that a delay in the second dose will not compromise the level of protection obtained after the second dose.
“We have countries facing future waves of disease right now with a largely unvaccinated population. That’s a situation where giving the first dose to more people, as soon as possible, is the most urgent priority, and certainly before the third doses are given, ”said Pollard, director of the Oxford Vaccine Group, department of Pediatrics from the University of Oxford.
“We should try to make sure that all of these vulnerable people – older adults, people with other health conditions and around the world are protected.”
The investigation was initially designed so that the timing of the second dose was varied to observe the persistence of immune responses after the first dose. Then, in 90 participants who had received the second dose, the researchers added a third dose to assess the immune response.
They found that a third dose of the AstraZeneca vaccine, administered more than six months after the second dose, leads to a substantial increase in antibodies and a strong boost to the immune response against the virus, including against the Alpha, Beta and Delta variants.
Data from Public Health England has shown that two doses of the vaccines being rolled out in the UK are enough to prevent more than 90% of hospitalizations, Pollard said.
“It’s hard to say if three doses would add another small percentage to that. But I don’t think we have any evidence that that’s the case at this point, ”he said. “The drivers have a lot more to do with whether protection is lost over time, and we don’t know, but if it does, could it increase? And the answer to that … is yes, you could. “
Professor Danny Altmann, an infectious disease immunology expert at Imperial College London who was not involved in the research, said the data comes at a time when there has been much concern about the evolution of vaccine protocols ahead of the evidence base of controlled studies. .
This document addresses some key questions, he noted. “Is an extended interval between the first and second doses a plus or minus sign for the response to the vaccine? Are there really any additional benefits to a third dose, or does the response stabilize after two? Does repeated vaccination lead to suppressed responses through vector inhibitory antibodies? “
“The responses at each count are encouraging. A big question now is whether these answers will be extrapolated to mRNA vaccines. “
George is Digismak’s reported cum editor with 13 years of experience in Journalism