Friday, May 27

More data needed if second dose of vaccine is diverted to beginners, says Covid advisor | Coronavirus


A senior government scientific adviser has said more data is needed before a proposal is adopted to give as many people as possible a starting dose of a Covid vaccine rather than preserving stocks so that there is enough for a second hit.

Former Prime Minister Tony Blair and Professor David Salisbury, a former Health Department director of immunization, backed the plan. Each person requires two doses to increase effectiveness, but they said existing limited stocks should be used to give a single dose to twice as many people, and the second injection is only given when more stocks are available.

While the suggestion would mean that every vulnerable person who received the vaccine would be afforded less protection, the number of people who received at least some would double.

Fast guide

How does the Pfizer / BioNTech Covid-19 vaccine work?

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The Pfizer / BioNTech Covid vaccine is an mRNA vaccine. Essentially, mRNA is a molecule used by living cells to convert the sequences of genes in DNA into proteins that are the building blocks of all its fundamental structures. A segment of DNA is copied (“transcribed”) into a fragment of mRNA, which in turn is “read” by the cell’s tools to synthesize proteins.

In the case of an mRNA vaccine, the mRNA of the virus is injected into the muscle and our own cells read it and synthesize the viral protein. The immune system reacts to these proteins, which by themselves cannot cause disease, as if they had been transmitted by the entire virus. This generates a protective response that studies suggest lasts for some time.

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The first two Covid-19 vaccines that announced the results of the three phase 3 trials were based on mRNA. They were the first to get out of the blocks because, as soon as the genetic code of Sars-CoV-2 was known, it was published by the Chinese in January 2020: companies that had been working on this technology were able to start producing the virus mRNA. Making conventional vaccines takes much longer.

Adam Finn, Professor of Pediatrics at the Bristol Children’s Vaccine Center, University of Bristol

But Professor Wendy Barclay, a member of the New and Emerging Respiratory Virus Threat Advisory Group (Nervtag), told the Commons science and technology committee: “I think the problem with that is that the vaccine is based on receiving two doses, and effectiveness is based on that foundation.

“To change at that point, one would have to see a lot more analysis perhaps coming out of the clinical trial data.”

Barclay agreed with Labor committee member Graham Stringer’s suggestion that any such change in established vaccine policy was “too risky.”

Blair had told BBC Radio 4’s Today program on Wednesday morning that the proposal to distribute the doses of the Pfizer vaccine that are already in government possession should be considered more broadly and sparsely because “the reality is that we are now in a severe block until vaccination. “

He said the AstraZeneca vaccine, which is expected to be approved this month and is easier to store and transport, could be used in the same way once it is available.

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“Does the first dose give you substantial immunity, and by that I mean more than 50% effective? If it does, there is a very strong case for not withholding doses of the vaccine, ”said Blair.

“If, in January, AstraZeneca gives you 10 or 20 million doses of the vaccine, you should vaccinate 10 or 20 million people because then you should get more vaccines by the time you’re ready for the second dose and that first dose can give your immunity. substantial “.

The former prime minister also criticized the “somewhat inflexible ‘by age’ structure” used to determine who gets the jab.

The experts of the Joint Committee on Vaccination and Immunization have developed a priority list based on clinical need. But Blair, who has no medical history, said “there are strong reasons to say that you also have to focus on the people who spread the disease, not just the most vulnerable.”

The Department of Health and Social Care has not responded to a request for comment.


www.theguardian.com

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