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Faced with growing cases of coronavirus, some European countries are considering whether to change their approach and join the UK in vaccinating as many people as possible with a single dose, rather than the two administered during clinical trials so far.
This issue has been published since December 30, when the United Kingdom announced the decision to postpone the second dose by up to 12 weeks, when it approved the Oxford / AstraZeneca vaccine for emergency use. The switch was also applied to the BioNTech / Pfizer jab.
Earlier this week, Denmark announced its decision to postpone the second dose of both Pfizer and future Moderna jabs for up to six weeks. The German Ministry of Health has also confirmed that it is considering expanding vaccine coverage through similar delays between doses.
Meanwhile, the US federal government is in talks with Moderna about halving the recommended dose to speed up immunization efforts.
Scientists are divided. Some argue that the delay could cause other mutations in the virus and make it inefficient. Others wonder if the beneficiaries will be left more vulnerable, pointing out that allowing larger dose gaps has not been tested correctly.
The pro-delay camp argues that a broader immediate level of protection, if slightly weaker, is better than providing stronger protection to half the number of people. The deputy chief medical officer of Great Britain, Jonathan Van-Tam, insisted on this point in the Mail on Sunday, saying that maximizing the coverage with the first dose will “save lives”.
The leading epidemiologist in Belgium, Pierre Van Damme, also supports the idea of discontinued dosing. Speaking to the VRT broadcaster last week, he said the strategy would quickly provide protection for more people and “the herd’s immunity will grow at a much faster rate.” (Belgian Health Minister Frank Vandenbroucke has asked the vaccine working group to look into the possibility of dose delays, but has not yet made a statement, with a spokesman warning that there is still not enough evidence for the move.
With the supply of squeezed vaccine and new variants of the coronavirus in Britain and South Africa, which is causing alarm – aggravated by overloaded health systems – some politicians are now heading to the latter camp.
Capture: Although the UK approach has been developed and supported by many public health scientists, it does not have the rigor of controlled testing in which the UK is so well versed.
It is not fully tested
The idea of vaccinating as many people as possible with the Oxford / AstraZeneca vaccine before it is approved for emergency use was first launched by former Prime Minister Tony Blair in early November. It was quickly rejected by doctors and scientists on the grounds that it would pass clinical trials already underway for these treatments. Such studies ultimately eliminate therapeutic winners (dexamethasone) from losers (hydroxychloroquine).
The debate changed this week as well, when the British Society for Immunology shook hands on Monday. While their statement placed “the greatest value on an evidence-based approach to medical decisions”, they called for a “pragmatic short-term approach”, given the “unprecedented situation”. The company backed the two-dose delayed program – provided the government developed a “robust immune monitoring program”.
Sheila Bird, former program leader at the University of Cambridge, MRC Biostatistics Unit, has taken it a step further. In an e-mailed statement, she called on the UK to randomize standard and delayed dosing schedules to compare the effectiveness of both approaches.
“The tests would be good for all these variations, although the data we have show very good protection against a dose of AstraZeneca or Pfizer [vaccines]”The speed and scale of vaccination is crucial to success,” said Professor John Bell, who is also a member of the UK Vaccine Working Group, in an email.
Data with a single photo
In their defense of delayed dosing, UK chief physicians indicated data showing that the short-term efficacy of the first dose vaccine is approximately 90% with the BioNTech / Pfizer vaccine and approximately 70% with the Oxford / AstraZeneca vaccine. The second dose will probably be “very important for the duration of protection,” they said in a joint letter on Dec. 31.
Some scientists, however, remain concerned about whether the efficacy could decrease beyond the indicated three- and four-week periods for the second dose of Pfizer and AstraZeneca vaccines, respectively.
Data from the British Society for Immunology on the BioNTech / Pfizer vaccine, for example, show that antibodies and T cells are more effectively neutralized after the second dose. The company also notes that “similarly, the Oxford / AstraZeneca vaccine shows substantial immunological differences after the second dose at 28 days”.
They concluded, however, that delaying a second dose by eight weeks “would be unlikely to have a negative effect on the overall post-boost immune response”.
Peter English, former editor of the journal Vaccines in Practice and former chair of the Public Health Committee of the British Medical Association, also presented the case of the delays. In an article published on Monday, he wrote that decades of experience with other vaccines have shown that, if anything, “increasing the interval will increase the quality of the booster response.”
Did a single approved dose come?
With Johnson & Johnson investigating the question in a large clinical trial, more data on single-dose efficacy and duration of protection are likely to be revealed by the end of the month.
Like the Oxford / AstraZeneca cage, the J&J vaccine is based on adenovirus viral vector technology. It uses a cold virus modified to carry information into cells, telling them to produce the spike protein antigen to build an immune response.
J&J, which has experience in pandemic vaccination after the approval and successful launch of its Ebola vaccine, said in November that while a single-dose vaccine “would have significant benefits, especially in a pandemic setting,” the company’s vaccination program also tests two doses in a separate study.
The unpublished early results from a first-stage clinical trial showed that a single dose is effective in generating sufficient antibodies in 98% of patients after 29 days, the company said.
Pending positive results, the US drug manufacturer intends to submit global data licenses to support the single-dose program. The European Medicines Agency hopes to make a decision in March.
Final obstacle
The British approach allows the off-label use of both Pfizer and AstraZeneca vaccines, which means that these jabs can be administered outside the authorized indication without consequences. This is possible thanks to instructions from the Joint Committee on Vaccination and Immunization, which provide protection against reprisals.
The same does not apply elsewhere in Europe, where countries will use EMA-approved vaccines.
“I don’t think that health professionals … in the EU would support or otherwise be inclined to promote any kind of unlabeled use,” said Vincenzo Salvatore, a lawyer at Bonella Erede and a former chief adviser at EMA.
“Any changes to [administration] would require a change in the marketing authorization, “the EMA said, as reported by Reuters,” as well as more clinical data to support such a change. Otherwise, it would be considered “off-label use”. “
Vaccine manufacturers also defended clinically approved indications.
“Our Phase 3 clinical trial and US emergency use authorization are associated with 100ug at two doses, 28 days apart,” a Moderna spokesman said in an email. half doses in the US
BioNTech echoed this sentiment in FT, reiterating that there are no data to support the administration of two doses of vaccine administered less than 21 days apart.
The Englishman, who is also a consultant in the fight against communicable diseases in the UK, said the benefit of the vaccine committee is that it “views the population and needs throughout”. It includes decades of knowledge about vaccines, the immune system and how they interact – “not just according to studies that have been done to get a license”.
He also warned of the deadly risk of limiting the factors that affect these decisions.
“People are divided into those who want explicit, limited, direct empirical evidence and those who are willing to extrapolate from indirect evidence,” he said. “The problem is that lives could be lost if we wait for narrow direct evidence.”
Charlie Cooper, Hans von der Burchard and Camille Gijs contributed to the reporting.
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