Omicron variant: transmission, vaccine efficacy … what the first studies say – LCI

Omicron appears to have a higher reinfection rate, but cause less severe symptoms, the World Health Organization (WHO) announced on Wednesday, while Pfizer and BioNTech laboratories assured that their vaccine against Covid-19 was “always effective” after three doses against this variant.

“Preliminary data from South Africa suggests risk of reinfection” people cured of the disease or vaccinated “higher with Omicron, but more data is needed” to draw firmer conclusions, cautiously declared WHO boss Tedros Adhanom Ghebreyesus. “There is also some evidence that Omicron causes less severe symptoms than Delta – currently the most common variant – but again it is too early to be certain,” he added.

Pfizer and BioNTech for their part insisted on the effectiveness of their current vaccine against the Omicron variant. These announcements were preceded by those of senior scientists from the WHO and the White House, according to which the existing vaccines against Covid-19 remain a priori relevant to this variant, the recent discovery of which in South Africa arouses a wind of panic. American virologist Angela Rasmussen said the first data published by Pfizer and other independent studies were “at least encouraging”. “A third dose will reduce the risk of infection occurring in those vaccinated”, she declared. But the first results, very partial, of a study also temper this optimism displayed. According to the Africa Health Research Institute (AHRI), a South African organization that sponsored one of Omicron’s first vaccine resistance studies, it “partly escapes the immunity conferred” by the Pfizer vaccine.

For now, therefore, be careful. “In the effectiveness of vaccines, it is only the antibodies that play, there is also what is called the cellular response. So, it is too premature what we have today as data. (…). It is far too early to venture into making predictions “, underlines Prof. Odile Launay, head of the Clinical Vaccines Investigation Center at Cochin Hospital (AP-HP), interviewed in the subject at the top of this article. Moreover, the 3rd dose should allow the antibodies to rise sufficiently. The Pfizer laboratory ensures that if necessary, it could provide a new vaccine by March 2022.