Not really reassuring words. The director of the WHO in Europe was more pessimistic this Friday, September 10 on the ability of a high vaccination rate to stop the Covid-19 pandemic on its own, because of the variants that have reduced the prospect of ‘collective immunity.
With an increased probability that the disease will remain endemic without being eradicated, Hans Kluge called, during a press conference, to “anticipate in order to adapt our vaccination strategies”, in particular on the issue of additional doses.
In May, the UN health official said that “the pandemic will (it) be over when we have reached a minimum vaccination coverage of 70%” of the world population. Asked whether that goal still holds or should be raised, Hans Kluge pointed out that the newer, more contagious variants, mainly Delta, have been a game-changer.
At the time, even though the variant initially detected in India was already rampant, “there was no such emergence of more transmissible and more viral variants,” he argued. “So I believe that brings us to the point where the essential objective of vaccination is above all to prevent severe forms of disease and mortality,” he stressed.
Collective immunity is illusory only with vaccines
“If we consider that the Covid will continue to mutate and stay with us, like the flu, then we must anticipate how to gradually adapt our vaccination strategy to endemic transmission, and acquire very valuable knowledge on the impact of additional doses” , he added.
According to epidemiologists, it now seems illusory to achieve collective immunity only through vaccines, but these remain crucial to contain the Covid-19 pandemic. A very high level of vaccination is also essential “to reduce the pressure on our health systems which desperately need to treat diseases other than Covid”, added Hans Kluge.
Now dominant, the Delta variant is judged to be 60% more transmissible than the Alpha and twice as much as the historical virus. However, the more contagious a virus, the higher is the threshold necessary for collective immunity, that is to say the threshold of immunized people beyond which the epidemic stops. This can be obtained through vaccines or natural infection.