(London) Pharmaceutical company AstraZeneca said Thursday that a third dose of its COVID-19 vaccine “significantly” increases the level of antibodies against Omicron, as this variant of the coronavirus sweeps across Europe and the United States .
“The levels of neutralizing antibodies Omicron after a third dose of Vaxzevria”, its anti-COVID-19 vaccine, “were generally similar to the levels reached after two doses against the Delta variant”, details the Anglo-Swedish giant in a press release.
“The levels observed after a third dose were higher than the antibodies found in individuals who had previously been infected and recovered naturally” of the other variants of COVID-19, specifies Astrazeneca.
The third dose study was conducted “independently” by researchers at the University of Oxford, with whom Astrazeneca designed its vaccine.
Vaxzevria was not selected for booster doses in the UK, after it had been the main vaccine used in the country for the first two doses, alongside Pfizer / BioNTech.
But developed countries favor mRNA vaccines like that of Pfizer, and AstraZeneca’s serum is now mainly redirected to the international Covax program, aimed at poor countries.
“It is very encouraging to see that the current vaccines have the potential to protect against Omicron after a third booster dose” commented John Bell, one of the researchers at the University of Oxford who conducted the study.
Several recent studies, carried out in the laboratory, show that the level of antibodies collapses against Omicron in vaccinated with Pfizer / BioNTech, Moderna, and even more AstraZeneca or the Chinese vaccine Sinovac.
Pfizer / BioNTech and Moderna also recently announced that a booster of their vaccine markedly increases protection against the virus. However, data is lacking to know how long this protection lasts.
According to the director of the World Health Organization (WHO) for Europe, Hans Kluge, the widely spread Omicron variant is becoming, or has already become, dominant in several countries including Denmark, Portugal and the United Kingdom.
Illusion of the third dose
The WHO boss, however, warned on Wednesday against the illusion that it would be enough to administer booster doses to get out of the COVID-19 pandemic.
Two studies conducted in Britain and published Wednesday show that Omicron variant infections are less likely to cause hospitalizations compared to the Delta variant, confirming a trend first seen in South Africa.
The Anglo-Swedish giant also announced in a separate statement Thursday that its long-acting antibody cocktail Evusheld for the prevention of COVID-19 remains effective against the Omicron variant, according to a study from the University of Oxford and from Washington University School of Medicine in St. Louis, United States.
“Consistent data from three independent studies shows that Evusheld […] remains effective against the Omicron variant at levels that provide benefit to patients, ”commented Mene Pangalos, AstraZeneca’s director of research and development for biopharmacy.
American health authorities have authorized the administration of synthetic antibodies developed by AstraZeneca in certain individuals who respond poorly to vaccines for medical reasons, in order to protect them against COVID-19 even before any exposure to the virus.
This is the first time that the United States Medicines Agency (FDA) has authorized such a pure prevention treatment as an emergency.
It is only authorized for people who are immunocompromised (in whom the vaccine is likely to work less well), or those who cannot be vaccinated for medical reasons (for example strong allergic reactions). In these cases, it can be administered from the age of 12.
Evusheld combines two types of synthetic antibodies (tixagevimab and cilgavimab), and is given as two intramuscular injections.
These antibodies help the immune system fight off the virus if it is encountered, by targeting its Spike protein, which allows it to enter cells to infect them.
For the moment, two cocktails of antibodies, those from the companies Regeneron and Eli lilly, are authorized for prevention in the United States, but only in people who have been exposed to the virus shortly before, or who have a good chance of being so. fact of their position (employees of retirement homes, prisons, etc.).