Covid-19 UK: Pfizer vaccine works better eight weeks apart, top scientists say

Professor Susanna Dunachie, a medical microbiologist at the University of Oxford, says she wouldn’t advise people to bring their second injection appointments forward.

Britons have been urged not to get their second Covid shot early as this could lead to weaker protection against the virus.

A study by scientists at the nation’s top universities found that having at least six weeks between doses of Pfizer’s vaccine boosts immunity, with eight weeks being the sweet spot.

It comes amid growing concerns that young people are rushing to get their top-up early so they can go on quarantine-free summer vacations to amber-listed destinations.

Some vaccine centers offer walk-in services, which have hired people who have had their first Pfizer shot three weeks in advance.

The study of 500 NHS staff found that waiting ten weeks instead of three weeks causes the body to produce more than twice as many antibodies to fight India’s ‘Delta’ Covid variant.

Professor Susanna Dunachie, a medical microbiologist at the University of Oxford and lead author of the study, said: ‘I think eight weeks is about the right place for me.

‘Because [while] people want to get the two vaccines and there’s a lot of Delta right now, unfortunately I don’t see this virus going away so you want to weigh that against getting the best possible protection.

“And there are also decisions at the population level.”

The government will also relax self-isolation rules next month for people who have had both vaccines, raising fears that people will try to get their second shot too early.

It comes from studies by AstraZeneca and Pfizer showing that immunity is strongest when there is a 12-week break between doses.

But ministers have shortened the regime to fully protect more people before the month gets colder and the NHS comes under further strain from flu.

It comes from studies by AstraZeneca and Pfizer showing that immunity is strongest when there is a 12-week break between doses.

Research by the Universities of Oxford, Newcastle, Sheffield, Liverpool and Birmingham showed that longer waiting times between Pfizer shots improves the number of antibodies produced by the body.  Graph shows: The level of antibodies against the original 'Victoria' Covid variant, the South African 'Beta' variant, the Brazilian 'Gamma' variant and the Indian 'Delta' variant in the blood of the participants after short (three to four weeks) and long (six to 14 weeks) intervals between vaccine doses

Research by the Universities of Oxford, Newcastle, Sheffield, Liverpool and Birmingham showed that longer waiting times between Pfizer shots improves the number of antibodies produced by the body. Graph shows: The level of antibodies against the original ‘Victoria’ Covid variant, the South African ‘Beta’ variant, the Brazilian ‘Gamma’ variant and the Indian ‘Delta’ variant in the blood of the participants after short (three to four weeks) and long (six to 14 weeks) intervals between vaccine doses

The PITCH study — funded by the Department of Health and Social Care (DHSC) — looked at immunity levels after “short” three to four weeks or “long” six to 14 weeks between the first and second dose.

It found that antibodies tended to decline between doses, but T cells — an essential part of the immune system — remained at the same level, meaning people were still protected against the virus.

Research was conducted by the universities of Oxford, Newcastle, Sheffield, Liverpool and Birmingham.

They took blood samples from participants to determine the level of antibodies and T cells – two crucial parts of the immune response to Covid.

It has not studied the effects of dosing intervals on the AstraZeneca vaccine, but the results are likely to be similar for the Moderna shot, which uses the same MRNA technology as Pfizer’s.

AstraZeneca’s vaccine is known to take a little longer to elicit an immune response than Pfizer and Moderna shots.

Of the 503 health professionals recruited for the study, 223 (44 percent) had previously had Covid, 76 percent were female, and 86 percent were white.

Researchers found antibody levels against the Delta variant low after a single dose and decreased for the second dose. But they were strong after both jabs.

And they were twice as high for people on a longer dosing interval compared to shorter ones.

T cells remained at the same level between doses, but were 1.6 times lower in people who had the long interval after both shots.

Researchers found that antibody levels against the Delta variant (shown in blue) were low after a single dose and decreased before the second dose.  But they were strong after both jabs

Researchers found that antibody levels against the Delta variant (shown in blue) were low after a single dose and decreased before the second dose. But they were strong after both jabs

The longer dosing interval resulted in higher antibodies for the ‘Indian’ Delta, ‘Kent’ Alpha, ‘South Africa’ Beta and ‘Brazil’ Gamma variants

At a news conference yesterday, the study authors said the results showed people should wait the full eight weeks between shots.

Professor Susanna Dunachie, a medical microbiologist at the University of Oxford, said the current recommendation is the best way to strike a balance between the need to fully vaccinate everyone as soon as possible and ensuring that they are fully vaccinated during the third wave. receive the best possible protection.

When asked what she would say to someone considering shortening the wait time between doses, she said she wouldn’t advise people to bring their second injection appointments forward.

When should I get my second dose?

The government’s top scientists say anyone under 40 should wait at least eight weeks before getting their second dose and no more than 12.

It comes after people over 40 shortened their second dose gap in light of the Indian variant last month.

Professor Anthony Harnden, who helped prepare the priority list for jabs, said he would not recommend getting the second dose of the AstraZeneca vaccine earlier than eight weeks after the first.

But he added that the second dose of the Pfizer shot can be given from three to 12 weeks after the first dose.

Numerous studies have suggested that both the Pfizer and AstraZeneca shots are more effective after a longer period between doses.

Second doses can be booked online with the NHS or received at walk-in clinics.

There are about eight million adults in Britain who have yet to receive their first dose.

Speaking at a press conference, Professor Dunachie said, “I think eight weeks is about the right place for me.

‘Because [while] people want to get the two vaccines and there’s a lot of Delta right now, unfortunately I don’t see this virus going away so you want to weigh that against getting the best possible protection.

“And there are also decisions at the population level.”

Professor Dunachie said: ‘I think it’s quite a balance because, like I said, this virus isn’t going away, so you really want to protect your population.

“And when you’re in the middle of a wave, you have to take every possible measure to control that, including vaccination.”

And Professor Miles Carrol, a public health expert at the University of Oxford, added: “The science says the extended interval isn’t harmful, it’s slightly better.”

Boris Johnson announced earlier this month that Britons under 40 will receive their second Covid shot after eight weeks instead of 12.

The prime minister claimed the new target was for all adults to be fully vaccinated by mid-September, when coronavirus rates are expected to rise and the NHS struggles with seasonal winter pressures.

Last month, the gap for the elderly was narrowed to protect millions of the most vulnerable amid the rise of India’s highly contagious strain.

Originally, both AstraZeneca and Pfizer’s vaccines were approved to be distributed at three-week intervals because that was the gap tested in the research trials.

But No10’s scientists pushed the regimen back to 12 weeks to gain wider protection over the winter, when the second wave began to lift.

Studies have since shown that both shots actually perform slightly better when the doses are spaced out over a month.

Vaccines Minister Nadhim Zahawi said: ‘The findings of this latest PITCH study are hugely important not just for the UK but for the world, helping us understand the mechanisms behind our immune response to Covid and the importance of getting both doses. of the vaccine better.

“As we raced to offer all adults a vaccine, we followed the advice of the JCVI to shorten the dosing interval from 12 to 8 weeks to protect more people against the Delta variant.

‘This latest study provides further evidence that this interval results in a strong immune response and supports our decision.

“I urge every adult to get both doses of the vaccine to protect yourself and those around you and we want to boost millions of the most vulnerable from September to ensure this protection is maintained. ‘

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