An eight to 10 week interval between doses of Pfizer’s Covid vaccine increases the effectiveness of the two-shot treatment compared to a shorter interval, according to a study in the United Kingdom (UK).
–Why is this important?
Extended intervals between shots promoted T cells. The body needs this to detect the virus and kill the infected cells. The vaccine also works better against Delta that way.Eight weeks is probably the sweet spot. It’s the perfect balance between fully vaccinating as many people as possible as soon as possible and getting the population to produce a higher number of antibodies, said Professor Susanna Dunachie, head of the study at the University of Oxford, during a briefing that followed Bloomberg on Thursday. .
After the UK vaccinated much of its population, it has seen infections rise sharply in recent weeks as the Delta variant spread. The increase in the number of cases has raised the question of whether the government should further shorten the recommended interval between doses, which was recently reduced from 12 weeks to eight.
“This latest study provides further evidence that the longer interval develops a strong immune response,” UK Vaccines Minister Nadhim Zahawi said in a statement.
The findings
The study looked at the immune response to the Pfizer vaccine at a dosing interval of three weeks to 10 weeks. While the vaccine was very effective over the entire period, the longer interval had a few additional benefits.
The number of neutralizing antibodies was twice as high after a 10-week break than after a 3-week break. It therefore works better against delta and all other tested variants of concern. The longer regimen also improved the response of the T cells, which support immune memory.
The findings have not yet been checked by fellow scientists, so cautious optimism is recommended.
Cons
However, a disadvantage of the longer interval was a decrease in the number of antibodies between the first and second dose. Particularly against the Delta variant, the study found. T cells were maintained well between injections.
Global studies show that both the short and long dosing schedules lead to strong real-world protection against Covid-19. That highlights the importance of a second dose of the vaccine, the scientists say.
*The study looked at the immune response of 503 health professionals in the UK, about three quarters of whom were women. The study was funded by the UK Department of Health and Social Care and conducted by scientists from the Universities of Oxford, Newcastle, Liverpool, Sheffield and Birmingham, with support from the UK’s Coronavirus Immunology Consortium.
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