Sunday, January 24, 2021

UK is postponing second dose of COVID vaccine to 12 weeks. Is it even safe?

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Stopping your medication is a sure-fire way to make your doctor worse. What if a whole country did it?

The UK has entered uncharted territory by changing course and introducing a revised COVID-19 vaccination protocol, which involves delivering the second dose to 12 weeks, rather than the prescribed 21 days.

It is a movement observed around the world.

British health officials say it is the best way to distribute a limited number of doses and contain a deadly wave of contagion that has pushed the country into a series of extended lockdowns and overwhelmed hospitals last month.

There is a big problem with the plan, however. There is little clinical evidence that a 12 week gap will be as effective as a 21 day gap. That alone, according to a growing number of health experts, makes it risky.

“I would not recommend extending the duration of the second dose as there is no clinical data to support it,” said Dr Paul Offit, leading pediatrician and vaccine researcher at the children’s hospital of Philadelphia. Fortune. “We just don’t know for sure how long the immunity lasts from a single dose beyond the four weeks.”

There are also practical issues: Offit said he was concerned the delay could mean more people fail to get a second dose at all, which ultimately undermines efforts to end the the pandemic – although the number of proposed doses will likely explode this spring as more and more vaccines are authorized.

Vaccine makers themselves are staunch opponents of the UK’s decision to space out doses, also warning of the lack of reliable data; The World Health Organization, for its part, recommended on January 8 that the wait between the first and the second dose not exceed six weeks.

In the United States, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in the United States, told CNN in early January that “we want to stick with what the science tells us” – in other words, do not deviate from the 21 day window.

“We make decisions based on data. We have no data on the administration of a single dose and the wait longer than the normal period of time [for the second dose],” he said.

The COVID crisis in the United States is no better than it is in the United Kingdom. For now, the plan is to tackle the problem by increasing the supply. On Tuesday, the Tump administration agreed to release all doses it built up, essentially matching a wish President-elect Joe Biden made free all current dose cache once he takes office.

Other countries, including Germany and Denmark, would have investigated whether stretching the second dose would save them time. For now, they are sticking to the prescribed rules.

The death toll is climbing

The UK recently passed 80,000 deaths from COVID, the most in Europe, as a highly contagious variant of the virus sneaks into towns and villages.

The government determined last month that one way to slow the contagion and reduce the impact on overworked hospitals would be to tinker with the dosing schedule. The decision sparked a fierce scientific and political debate, balancing a lack of data on whether it is safe or reasonable to use ‘off-the-book’ vaccines – and desperate circumstances which some say are worthwhile. efforts to save as many lives as possible.

“We calculate that this decision will maximize the reductions in hospitalizations and deaths that must be our current goal. It is biologically plausible that the delay (not cancellation!) Of the second dose will not leave recipients defenseless, ”said Robert Read, professor of infectious diseases at the University of Southampton and member of the UK Joint Committee for Vaccination and Immunization.

Of course, “biologically plausible” is not a standard that can inspire a fantastic degree of public confidence. But the dire situation the UK finds itself in, with soaring infection and hospitalization rates, has turned a public health dilemma into an ethical dilemma.

“It’s not a simple problem,” added Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, commenting on the UK’s decision last week. “The idea that there is a clear and precise answer is not true because respected scientists differ in their views.”

What the data say

the Pfizer BioNtech vaccine trials did not compare variations in dosing regimens, noted one article published in the BMJ, the British Medical Journal, while trials of the Oxford AstraZeneca vaccine suggested that a longer gap might actually improve immunity – but the number of people tested for this gap is small.

There is a salutary potential: vaccines, by traditional measures, are remarkably powerful. While the Pfizer and BioNTech vaccine, for example, requires two doses to achieve 95% effectiveness, the success of the first dose is still 52%, according to vaccine trials.

And, in a crisis, even this reduced effectiveness can do a lot of good. “When resources for doses and people to be vaccinated are limited, then vaccinating more people with potentially less effectiveness is clearly better than more complete effectiveness in only half,” said Evans, of the London School of Hygiene. and Tropical Medicine.

But it is not that simple. There are warnings that the success of waiting longer to give a second dose can vary widely, depending on the vaccine itself. The Oxford-AstraZeneca vaccine, and others that rely on a viral vector to provide immunity, may actually benefit from a longer wait between doses; but RNA-based vaccines like Moderna and Pfizer vaccines could have fundamentally different responses, scientists say.

Such potential differences may mean that the smarter approach would be to vary the time between doses, not only depending on the vaccine, but the recipient, argues Stephen Griffin, associate professor in the University of Medicine School of Medicine. Leeds. For example, this may mean sticking as close as possible to the 21-day window determined by the trial that the Pfizer-BioNTech vaccine calls for, for example, for a more vulnerable patient while still allowing more flexible ranges for d ‘others in better health.

However, that would be an approach that would allow a certain level of flexibility – something that desperate governments, grappling with death rates and vaccine shortages, could also be dangerously low on.

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