British Scientists Say That An Eight-week Interval Between The Two Doses Of Pfizer Is "The Ideal"

An eight-week interval between the first and second doses of the Pfizer / BioNTech vaccine is “ideal” when it comes to generating a strong immune response and protecting the population against the delta variant of the coronavirus, according to British scientists and picks up the agency PA Media.

In a study funded by the Department of Health and Social Care, researchers have concluded that, compared to a four-week interval, a 10-week interval between doses produces higher levels of antibodies, as well as a higher proportion of a group of infection-fighting cells in the body known as helper T cells.

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At the beginning of the second wave of the COVID-19 pandemic, the British Joint Committee on Vaccination and Immunization (JCVI) made the decision to recommend a 12-week interval between two doses for the two vaccines available at that time: Pfizer and Oxford. / AstraZeneca. This occurred at a time when vaccines were in short supply and preliminary research suggested that extending the manufacturer’s recommended four-week interval to 12 increased the immune response.

But the guideline was changed in May to eight weeks, as cases associated with the delta variant continued to rise in the UK.

“The JCVI’s initial recommendation was 12 weeks and was based on knowledge of other vaccines, that often a longer interval [entre las dosis] gives the immune system the opportunity to give the maximum response “, says Professor Susanna Duanchie, from the University of Oxford, researcher on the study, according to PA Media.” The decision to do it at eight weeks is truly a balance between all aspects relevant, the pros and cons. Two doses are better than one overall. You also have to balance other factors, [como] the supply of vaccines, the desire to reopen, etc. “.

“Eight weeks is ideal for me, because people want to wear both [dosis] and there’s a lot of delta right now, “says Duanchie.” Unfortunately, I don’t think this virus is going away, so you have to balance it with the best possible protection. “

For the trial, the researchers recruited 503 healthcare workers, 44% (223) of whom had previously had COVID-19, and studied the immune responses generated by Pfizer’s vaccine.

They found that both the short (three to four week) and long (10 week) intervals of the Pfizer vaccine elicited strong antibody and T-cell immune responses.

But the longer pattern led to higher levels of antibodies and a higher proportion of helper T cells, which the researchers say supports immune memory, reports the British agency.

The scientists found that after the second dose, a wider range also resulted in higher levels of neutralizing antibodies against the delta variant and all other variants of concern. But in this case, antibody levels dropped between the first and second doses, leaving recipients vulnerable to the delta variant after an injection.

However, one of the authors, Dr Rebecca Payne, from the University of Newcastle, says that the cellular response of T cells was maintained in both the long and short patterns, “indicating that they may contribute to an important protection against Sars-CoV-2 during this time. ”

“After the second dose in the longer regimen, the antibody levels exceeded those seen at the same point after a shorter interval,” he says. “Although the T cell levels were comparatively lower, the profile of the T cells present suggested greater support for immune memory and antibody generation.”

The researchers say there may be exceptions where the schedule needs to be shortened from eight to four weeks, such as for those who are going to undergo treatments that can affect the immune system, such as cancer or organ transplantation. “I would say then that they should be vaccinated as soon as possible,” says Dr. Lance Turtle of the University of Liverpool, who specializes in T-cell studies.

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