Longer interval between doses of Pfizer vaccine increases antibodies, study finds

Scientists around the world, for the past year and a half, have been testing all kinds of strategies to fight COVID-19. With the emergence of emergency vaccines, much has been said about the time interval between two doses. Now an interval eight to 10 weeks between doses of vaccine Covid-19 developped by Pfizer and BioNTech, the effectiveness of the two-injection regimen is increased compared to a shorter interval, according to a British study.

Professor Susanna Dunachie, head of the study at the University of Oxford, said in a briefing on Thursday: ‘Eight weeks is probably the sweet spot, in terms of the trade-off between vaccinating as many people as possible and allowing the population to produce higher levels of antibodies ”.

After inoculating a higher proportion of people than any other large economy, Britain has seen infections increase in recent weeks as the Delta variant spreads. The spike in cases has sparked debate over whether the government should further shorten the recommended interval between doses, which was recently reduced by 12 weeks to eight.

“This latest study provides more evidence that this interval causes a strong immune response and supports our decisionUK Vaccine Minister Nadhim Zahawi said in a statement.

The study looked at the immune response of 503 British healthcare workers, of whom around three-quarters were women. It was funded by the UK Department of Health and Welfare and conducted by scientists from the universities of Oxford, Newcastle, Liverpool, Sheffield and Birmingham, with support from the UK Coronavirus Immunology Consortium.

Research has analyzed the immune response to Pfizer vaccine at a dosing interval of three to ten weeks. While the shot generated a strong reaction over time, the longer gap showed some benefit.

Neutralizing antibody levels were twice as high after the 10-week interval compared to the three-week period, even against delta and all other variants of interest tested. The longer diet also improved the response of T helper cells, which support immune memory. The results have not been peer reviewed.

However, a downside to the longer interval was a decrease in antibody levels between the first and second dose, especially against the delta variant, according to the study. The T cells held up well between takes.

Global studies show that both short and long dosing regimens lead to strong real-world protection against Covid-19, highlighting the importance of having a second dose of the vaccine, the scientists said.

According to another study published in the New England Journal of Medicine, two doses of the COVID-19 vaccine from Pfizer or AstraZeneca are almost as effective against the Delta variant of the coronavirus, highly transmissible, as against the Alpha variant, which was the most widespread in the world.

The study confirmed the main results of Public Health England in May on the effectiveness of COVID-19 vaccines manufactured by Pfizer-BioNTech and Oxford-AstraZeneca, based on real world data.

This research found that after receiving two doses of the Pfizer injection It was 88% effective in preventing symptomatic disease of the Delta variant, compared to 93.7% against the Alpha variant, as previously reported.

Two injections of the AstraZeneca vaccine were 67% effective against the Delta variant, compared to 60% initially reported, and 74.5% effective against the Alpha variant, against an initial estimate of effectiveness of 66%. “Only modest differences in vaccine efficacy were seen with the Delta variant compared to the Alpha variant after receiving two doses of the vaccine,” Public Health England researchers wrote in the study.

KEEP READING: