Delta variant: vaccinated and unvaccinated are infected with the same viral load

As experts have been saying since the start of the coronavirus pandemic, vaccinating people against the virus that emerged in Wuhan is the only way to control viral circulation and end the health emergency.

Having two doses of one of the authorized emergency vaccines is known to be the most effective way to ensure protection against SARS-CoV-2, although specialists are also working to clarify that even if a person is fully vaccinated, this does not prevent them from catching the virus, although it is believed that the disease will arise in a milder way.

Now researchers at the University of Oxford in the UK revealed that the Delta variant of the coronavirus infects vaccinated people with the same viral load as those who are not.

According to a preliminary analysis of a study carried out by experts from this British House of Higher Studies, and which was published in the journal BMJ, Those infected with the Delta variant have similar levels of the virus to those who have not been vaccinated, which presents “a greater challenge” when it comes to gaining group immunity to the coronavirus.

Specifically, in the book, published as a pre-publication and not yet peer reviewed, The vaccines developed by the AstraZeneca and Pfizer / BioNTech laboratories have been shown to offer good protection against new infections, but not as much with the Delta variant.

Sarah Walker is professor of medical statistics and epidemiology at the University of Oxford and principal investigator of the survey, admitting that they still don’t know “how much transmission can occur from people who contract COVID- 19 after being vaccinated, for example, if he may have high levels of the virus for shorter periods ”.

To reach this conclusion, Researchers analyzed 2,580,021 results from swabs taken from 384,543 adults between December 1, 2020 and May 16, 2021, when the Alpha variant predominated, and 811,624 results from 358,983 adults between May 17 and August 1, 2021. , when the circulation of the Delta mutation prevailed in this country.

This is how they found that when the Delta variant was predominant in the population, Pfizer vaccine efficacy was 80% at 14 days or more after the full two-dose schedule. And while this value was higher than that seen after two doses of the AstraZeneca vaccine, which was 67%, the researchers analyzed that it was not significantly different from the protection provided by natural immunity in unvaccinated people who tested positive for SARS-CoV-2, which was 72%.

After analyzing the data obtained, the experts concluded that “The effectiveness of the two vaccines did not depend on the time elapsed between the first and second dose, although people who were vaccinated after suffering from COVID-19 had more protection from the vaccines than those who were vaccinated without natural infection before “.

For example, 14 days after a second dose of AstraZeneca’s formulation, on average, the rates of all new COVID-19 infections had decreased by 88% among those previously infected, compared to 68% of those previously infected. who had not succeeded. COVID-19[FEMININELespourcentagesétaientrespectivementde93%et85%pourlesvaccinsPfizeretBioNTech

L’étude a également montré que la charge virale était plus faible immédiatement après les deux doses de Pfizer, mais augmentait plus rapidement dans le temps qu’après le vaccin AstraZeneca, conduisant à des niveaux de charge virale similaires à trois mois après la deuxième dose des deux vaccins.

“Il existe maintenant des preuves considérables que tous les vaccins sont bien meilleurs pour réduire le risque de maladie grave que pour réduire le risque d’infection”, ont conclu les chercheurs, notant qu’ils savent désormais “que la vaccination n’arrêtera pas l’infection et la transmission, mais elle réduire le risque. La principale valeur de la vaccination est de réduire le risque de maladie grave et de décès ».

D’autre part, la probabilité que les personnes vaccinées avec le régime complet soient hospitalisées après avoir contracté COVID-19 est réduite de 73% par rapport aux non vaccinés, comme le montre une grande étude britannique publiée dans La Lancette.

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