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People in Britain will receive their first shots of the Oxford / AstraZeneca vaccine on Monday, and millions of doses will be administered over the next few months. Mass vaccination of the UK population should end the country’s Covid-19 misery, but how long will this immunization program take to make a difference in our lives and what will be the first signs that salvation is in the offing? way? ?
These key issues will be pursued with anxiety as the battle against Covid progresses and daily cases related to the new variant of the virus continue to spread. However, scientists have cautioned that simply waiting for a reduction in new cases is not the way to know if the vaccine is beginning to have an impact.
This point was highlighted by Professor Adam Finn of the University of Bristol. “In February, we can see a big decrease in the number of cases,” he told the Observer. “That would be good news, but we would not know if the drop was due to the vaccine, the lockdown measures or some other factor.
“On the contrary, the number of cases may increase in February and March, and you could come to the false conclusion that the vaccine was not working when, in fact, the increase was due to other factors, and the increase in daily cases would have been even greater if we had not been vaccinating.
“So looking at general trends will not give us short-term answers. Obviously, we hope that the vaccine will have an effect, but we will have to be smart to find the first signs that it is working. “
A project that should provide the first indication that the national vaccination program is having a beneficial impact is being carried out at the University of Bristol and includes cases of pneumonia. In a case-control study, doctors will compare people with pneumonia who test positive for Covid-19 with patients who have pneumonia but test negative for the virus.
“Then we will measure the immunization rates within those two groups,” Finn said. “That will allow us to calculate how effective vaccines are, because you will expect to see that a much larger proportion of people who get sick are those who are not immunized.
“That will give us, very quickly, an indication of how effective the vaccine is. And finding pneumonia cases to compare will not be a problem at this time of year. There are always a lot of these in winter. “
The Bristol pneumonia study and other similar trials will provide the first signs that the UK is on the right track and that the vaccine is starting to make a difference. The next indication will come when the number of hospitalizations and deaths steadily decreases to a level where scientists can be sure that it is a Covid-19 vaccine that is producing real results and that other factors are not involved.
The UK will then know how effective its immunization strategy has been. This should resolve a dispute that has led some doctors and scientists, including leading US infectious disease expert Dr. Anthony Fauci, to question Britain’s decision to delay the administration of second doses of Covid-19 vaccines. to maximize the number of people who could be protected. quickly against disease.
Fauci told CNN on Friday that while it was possible to “argue” to extend the doses, he would not be in favor of doing so.
This view was shared by Professor Martin Hibberd of the London School of Hygiene and Tropical Medicine, who said: “Science has been of a very high standard for vaccine trials, and it is very frustrating that it is now being ignored. . We don’t know how the vaccine will work with a larger gap between injections, and we don’t know how protective a single injection will be in the long run. So why take the risk? “
However, Professor Chris Whitty, England’s chief medical officer, along with his counterparts in Wales, Scotland and Northern Ireland, have said that they stand by their decision to delay a second dose to ensure that more people can receive their first dose. as soon as possible.
And this view was supported by Professor Stephen Evans, also from the London School of Hygiene and Tropical Medicine: “We have a crisis situation in the UK with a new variant spreading rapidly and, as has become clear to everyone during 2020, delay the cost lives. When dose resources and people to administer vaccines are limited, vaccinating more people with potentially less efficacy is demonstrably better than more comprehensive efficacy by only half. “
