At first glance, the numbers would be cause for concern. The number of new daily cases of COVID-19 in the United Kingdom, where the delta variant – the more transmissible – is now in the majority, has increased by 61% in a week. This Wednesday evening, the curve should also “cross” France, in free fall for a month and a half.
And yet, if scientists and British officials in general are concerned, one element has something to reassure them: the apparent effectiveness of vaccines. More than one in two British adults received the two doses, twice as many as in France. In the most affected areas, such as the north-west of England, the increased incidence is rarely visible, except in people under 60 years of age, and especially young adults. However, the further down we go in age groups, the fewer vaccines we get. Hospitalizations are also increasing, but in a lower proportion than new cases. And again, it’s almost the same in those under 65.
Three reasons may explain why the growth of hospital admissions is slower than new cases. First, there is always a gap of about ten days between the two curves, so you have to be careful in interpreting the data. In addition, as we have seen, infected people have a shorter lifespan. So they are less likely to be affected by the severe form of the disease.
Finally, “people who have been vaccinated have little or no transmission of the virus, and in the event of infection, they often develop mild forms of the disease,” said François Méganon, a London-based pharmacovigilance specialist. . “The vaccine breaks the link between infections, hospitalizations and deaths,” British Health Minister Matt Hancock told parliament on Monday.
race against time
According to data from Public Health England, the majority of confirmed cases of this delta variant (the so-called “Indian”) and hospitalized patients were not vaccinated, or received only the first dose. more than three weeks old. Only 4% of positive people had both injections, even though this is the case for 43% of the population of all ages.
In mid-May, the British Health Agency reported that Pfizer would prevent 87.9% of symptomatic forms due to the delta version at least two weeks after the second dose, compared to 93.4% against the alpha version (“British”). A little less efficiency than either, but which remains good. The effect will be much greater after a single dose, as the effectiveness will be reduced by 20 points. And AstraZeneca, which is widely used in the United Kingdom, is showing less good results. But be careful: these are only “observational” data, which may contain some bias. And we don’t yet have scientific studies of the risk of transmission and the severe form of the disease.
It is difficult to say, in the short term, who will win in this “race against time” between variants and vaccinations. A large part of the British population (around 40%) has not yet received any supplements and is therefore still particularly vulnerable. To maximize the chances in its favor, the government on Tuesday lowered the age limit for vaccination in England to 25 from 30 years ago. It may also decide to postpone the final phase scheduled for June 21 by a few days or a few weeks.