Covid: facing Omicron, the effectiveness of the booster dose of the Pfizer vaccine decreases after three months

According to a new study, the effectiveness of the booster dose of the anti-Covid vaccine from Pfizer decreases against the Omicron variant as early as the third month following the injection.

The emergence of new variants of Covid-19 leads to an evolution of the data relating to the protection offered by vaccines intended to fight against the virus. Thus, a study published in the journal The Lancet Respiratory Medicine reveals that the protection offered by a booster dose of Pfizer against the variant Omicron decreases after only three months.

“Pfizer/BioNtech Covid-19 Booster Doses Significantly Improve Protection Against Omicron Variant, But Three Months After Injection, Efficacy Against Hospital Admissions Declines”says American epidemiologist Sara Y. Tartof of the Kaiser Permanente Health Consortium, lead author of the study.

Clearly, compared to Omicron, a booster dose of the Pfizer vaccine offers effective protection – around 85% – against hospitalizations in the three months following the injection, but this drops to around 55% beyond these three months. Also according to this study, carried out in California on a sample of 11,123 patients hospitalized or admitted to the emergency room for acute respiratory infection between December 2021 and February 2022, the protection offered by a booster dose of the Pfizer vaccine also drops in the face of the variant. Delta but slower than against Omicron.

For Sara Y. Tartof, the injection of additional doses of vaccines adapted to new strains of the virus “may be required to maintain high levels of protection against future waves caused by Omicron or future variants with a similar ability to evade protection”.

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