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Scientists have criticized the new guideline that allows for vaccine sharing, if the second dose of the vaccine originally received is not available, saying officials have abandoned the science and are only trying to “ guess how to get out of the mess. ”
Amid the launch of a cathodic vaccine and fears of a new and potentially more transmissible variant of the coronavirus
, Great Britain has quietly updated its vaccination manual to allow for a combination and combination vaccine regimen. If a second dose of the vaccine a patient originally received is not available, or if the manufacturer of the first injection is unknown, it can be substituted for another vaccine, health officials said.
The new guidance contradicts guidelines in the United States, where the Centers for Disease Control and Prevention has noted that authorization COVID-19 the vaccines “are not interchangeable” and that “the safety and efficacy of a number of mixed products have not been evaluated. Both doses in the series must be completed with the same product ”.
Some scientists say Britain is gambling with its new guidance. “There is no data on this idea at all,” said John Moore, a vaccine expert at Cornell University. Officials in Britain “seem to have dropped science entirely now and are just trying to figure out how to get out of the mess.”
Health officials in Britain are caught in a deadly race with the virus, which is on the rise again, and they are scrambling to vaccinate as many people as possible. Hospitals continue to push under an agglomeration of coronavirus patients, and tens of thousands of new infections are reported every day. Schools in London and other regions affected by the virus will remain closed for at least the next two weeks, government officials said on Friday.
The country has given an emergency green light to two vaccines, developed by Pfizer and AstraZeneca. According to Britain’s new guidance, “every effort should be made” to complete a dosing regimen with the same injection that was used for the first time. But when “the same vaccine is not available, or if the first product received is unknown, it is reasonable to offer a dose of the product available locally” the second time.
“This option is preferred if the person is likely to be at immediate high risk or considered unlikely to attend again,” the recommendation said. Because both vaccines target the spike protein of the coronavirus , “The second dose is likely to help improve the response to the first dose.”
Following requests for comment, Public Health England officials drew attention to the similarities between the Pfizer and AstraZeneca vaccines and said that clinical trials testing mixed regimens would begin sometime this year.
It is far from safe that the vaccines are interchangeable, several researchers said.
“None of this is based on data at this time,” said Dr. Phyllis Tien, an infectious disease physician at the University of California, San Francisco. “We are in this wild west.”
Steven Danehy, a spokesman for Pfizer, noted the results of the company’s late-stage clinical trials, which were based on a two-dose schedule of its vaccine that was 95 percent effective in preventing COVID-19 .
“While decisions about alternative dosing regimens rest with health authorities, Pfizer believes that it is critical that health authorities undertake surveillance efforts in any alternative program implemented and to ensure that each recipient receives the maximum protection possible, which means immunization with two doses of the vaccine. ” Danehy said.
Both the Pfizer and AstraZeneca vaccines deliver a protein called pico into the body that, while not itself infectious, can teach immune cells to recognize and fight real disease. coronavirus .
But vaccines teach their immunological lessons through different methods and do not contain equivalent ingredients. While Pfizer’s vaccine is based on a molecule called messenger RNA, or mRNA, packaged in greasy bubbles, AstraZeneca injections are designed around a virus shell that releases DNA, a cousin of mRNA.
Both vaccines are designed to be given in two-shot regimens, three to four weeks apart. While the first few shots of each vaccine are believed to be somewhat effective in preventing COVID-19 , is the second dose, thought as a kind of molecular review session for the immune system, which ensures the protective process.
While it is possible that swapping one vaccine for another can educate the body to recognize the coronavirus
Without supporting evidence, the hybrid vaccination approach appears “premature,” said Saad Omer, a vaccine expert at Yale University. Still, it’s not without precedent: Health authorities like the CDC have previously said that if it is impossible to administer doses of a vaccine from the same manufacturer, “providers must administer the vaccine they have available” to complete an injection schedule.
In a controversial move, the British government also decided this week to advance the launch of the vaccine, delivering as many first doses to people as possible, a move that could delay second injections by up to 12 weeks.
Rapid deployment could provide more people with partial protection against the virus in the short term. But some experts, including Moore, worry that this too is reckless and could endanger vulnerable populations.
A vaccination gap that lasts too long can cripple the ability of the second injection to increase the protective powers of the first, or increase the chances that people will forget or decide not to return for another injection.
The whiplash changes in the guide in Britain, many made without public meetings or solid data, can erode confidence in vaccination campaigns and public health measures in general, Tien said.
“We’re assuming the public is just going to listen and come in and get the vaccine,” he said. “I am concerned that that will not happen.”
Katherine J Wu c.2021 The New York Times Company
