The administration of third doses of vaccines against Covid-19 had already been debated for months by experts and political leaders. However, with the rapid spread of the Delta variant, pressure has increased on governments to draw up a new vaccination plan for the coming months, so that the immunization of populations is reinforced.
The Delta variant, first detected in India, has a higher degree of transmissibility and is already present in 92 countries, as warned by the World Health Organization.
+ Which vaccines are most protective against the Indian Coronavirus variant?
With the situation worsening, more and more voices in the scientific community are asking political leaders to prepare the purchase of more vaccines to reinforce the immunization of the population.
Doubts now fall on the duration of immunity and whether the eventual third dose should correspond to the brand of vaccine administered in the first two doses or whether a booster should be made with another brand, a hypothesis that has already been advanced by some scientists as being the most effective to boost the immune response.
There is also the possibility for pharmaceutical companies to manipulate existing vaccines to adapt them to new variants, similar to what is done annually with the flu virus.
In May, the UK began a study that is looking at administering a third dose of vaccine different from the first two. The results, which focused on seven brands of vaccines, should be completed in September.
So far, vaccines have proven resistant to new variants, remaining largely effective in preventing severe Covid-19 for fully vaccinated people. An analysis by Public Health England, released on Monday (21), revealed that two doses of the Pfizer, BioNTech or AstraZeneca vaccines were highly effective in preventing hospitalization of patients infected with the Delta variant.
+ Learn about the effectiveness of each vaccine against Covid-19