Will a third dose be needed? A new vaccine targeted specifically on the Delta variant? Or will the initial two injections of current vaccines be enough to protect populations? So many questions that have agitated vaccine manufacturers mobilized against Covid-19 for months. Faced with the new outbreak of the epidemic, pharmaceutical companies continue to sharpen their arsenal against the virus. However, the latter must contend with the permanent threat of the emergence of new variants, potentially more virulent and more resistant, which could one day escape the protective net offered by vaccines already approved.
So far, first-generation vaccines, whether messenger RNA (Pfizer-BioNTech, Moderna) or adenovirus (AstraZeneca, Johnson & Johnson) have proven to be globally effective in countering new strains of the virus that have emerged since the start of the pandemic, in particular against the Alpha variant, first detected in September 2020 in the United Kingdom, and which had become the dominant strain in the world, but also against the recent Delta variant .
Appeared in spring in India, this strain – 40% to 60% more contagious – is expected to account for 90% of new infections in Europe by the end of August, according to the European Center for Disease Prevention and Control. If current vaccines remain effective, pharmaceutical companies are however aware that this may not last. On the lookout, they continuously track each new mutation of the virus.
” Be proactive “
“We have surveillance systems in all countries, all over the world. When a new variant appears, we immediately test the behavior of the current vaccine in relation to this variant ”, explained, in mid-June, the boss of Pfizer, Albert Bourla, on the American television channel CBS News. But it’s not just about tracking variants. “As we seek to defeat the pandemic, it is imperative that we be proactive as the virus evolves”, insisted Stéphane Bancel, CEO of Moderna, in June.
For this, manufacturers are studying several options. First, that of a booster vaccination, which would make it possible, thanks to the injection of a third dose, to strengthen the immunity already acquired during the first bites, and to confer increased protection against new variants. Pushed for months by the laboratories – which also see in it the opportunity for juicy additional profits – this hypothesis is gradually gaining ground, but it has not yet obtained the approval of the health authorities.
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