LONDON – Initial studies on Britain’s major inclusion program on Monday showed strong evidence that the coronavirus vaccines were working as expected, offering among the clearest signs yet that the vaccines are reducing Covid’s hospital admission rate -19 and may reduce the transmission of the virus.
A single dose of AstraZeneca vaccine or the one made by Pfizer could stop most coronavirus-related hospitals, the British studies found, although researchers said it was too early to make accurate estimates. comment on the impact.
The conclusions about the design of AstraZeneca, the first to emerge outside of clinical trials, represented the strongest indication yet of a vaccine efficacy that many in the world rely on to end the pandemic.
And individual studies of the Pfizer vaccine offered tantalizing new evidence that a single image could reduce the spread of the virus, showing that it not only prevents symbolic cases of Covid-19 but also asymptomatic diseases.
The findings were confirmed and passed on studies out of Israel, which have also reported that the vaccine developed by Pfizer and BioNTech offered great protection from the virus in real-world conditions. -world, and not just in the clinical trials conducted last year. No other major country is bringing in people as fast as Britain, and it was the first country in the world to authorize and start using both the Pfizer bullet and the one that was developed by AstraZeneca and Oxford University.
Studies published on Monday – two on the Pfizer and one on and the AstraZeneca injection – showed that both vaccines were effective against the more contagious coronavirus variant that has spread in Britain and has spread across the world. -world.
“They’re both doing a fantastic job,” said Aziz Sheikh, a professor at the University of Edinburgh who helped run a study of Scotland’s vaccines.
However, the findings meant some warning signs. And even as British lawmakers praised the strength of vaccines in announcing a gradual reduction in blocking restrictions, government scientists warned that many more people would have to be injected. to prevent cases from spreading into vulnerable groups, vaccines and sometimes causing serious infection and death.
Britain has decided to delay giving second doses of the Pfizer and AstraZeneca vaccines until up to three months after their first dose, choosing to offer partial protection of one picture to more people.
The benefits of that strategy were not entirely clear from the evidence published Monday, but government scientists said the significantly reduced hospitalization rates justified the pre- ingenuity.
But the findings also suggested that people would be better protected from the coronavirus after a second dose. And they offered mixed answers to the question of how long high levels of protection would last from a single dose.
“We now need to understand how long this protection lasts for a dose of the vaccine,” said Arne Akbar, a professor at University College London and president of the British Society of Immunology.
One of the new studies looked at around 19,000 health workers in England who received the Pfizer vaccine. Scientists were able to monitor abnormally whether the subjects were infected or not: they were regularly tested for the virus, whether they were showing symptoms or not, allowing the scientists to detect asymptomatic cases.
Many of the clinical trials, by contrast, measured only symbolic diseases.
That study showed that a single dose of the Pfizer vaccine reduced the risk of being caught by about 70 percent. After two doses of the vaccine, immunity rose to 85 percent, scientists said, although they warned that the low numbers of cases made it difficult to reach accurate estimates.
The Pfizer vaccine also appeared to be effective in the elderly, underrepresented in clinical trials and does not always elicit strong responses to vaccines. In people over 80 in England, a separate study showed that a single dose was 57 percent effective in preventing Covid-19 symptomatic cases. Protection rose to 88 percent after a second dose.
Elderly people who received the first dose of the vaccine and became ill at least two weeks later had significantly lower deficiencies than those who were unvaccinated in hospital or died, suggesting that their Pfizer vaccines the effects of diseases even when it has not completely stopped them.
However, some people who received the vaccine were hospitalized or killed by the virus, a reminder that “protection is not complete,” said Dr. Mary Ramsay, head of vaccination at Public Health England.
A study carried out in Scotland included both Pfizer and AstraZeneca injections. Results on the AstraZeneca vaccine were more limited as it was later approved in Britain, only coming into use in early January.
Researchers there examined approximately 8,000 coronavirus-related hospital admissions, and examined how hospital risk varied among people who did and did not receive a bullet.
The numbers of vaccinated people seeking care in hospitals were so small, the researchers said, that they could only make very rough estimates of the effectiveness of the vaccines, and could not compare between the scenes to each other.
But from 28 to 34 days after the first sighting, when it appeared to be at or near efficacy, the AstraZeneca vaccine reduced the risk of Covid-19 hospital admissions by about 94 s. hundred. In the same period, the Pfizer vaccine reduced hospital risk by about 85 percent, but in all cases, the numbers were too small to be confident about the true effect.
The findings were an encouraging sign of the effectiveness of the AstraZeneca vaccine, which is the backbone of many countries’ inclusion plans. It is much cheaper to produce and unlike the Pfizer vaccine – and one from Moderna, which is not used in Britain – it can be discarded and stored in conventional coolers.
But British studies have not been able to address how long high levels of protection from a single dose of the Pfizer or AstraZeneca vaccine can last.
In the Scottish study, the fall in the risk of people being hospitalized began one week after first sighting, and reached a low level four to five weeks after receiving the vaccine. But then he appeared rising again.
“The maximum protection is at four weeks, and then it starts to fall off,” said Simon Clarke, a professor of cell microbiology at Reading University, who was not involved in the study.
In England, there was no evidence that protection levels fell after a month. Scientists said more evidence was needed to definitively determine whether and how quickly the protection used by a single dose was weakening.
The AstraZeneca vaccine has been used against suspicion in parts of Europe; Many countries chose not to give it to the elderly, citing the lack of clinical trial data in that group.
The Scottish study was unable to provide accurate figures on the effectiveness of the vaccine in the elderly. But the inoculation program has largely gone into hospitalization in people older than 80, and many older people received the AstraZeneca vaccine.