While the vaccine’s effectiveness against infection risk decreases over time, from 88% to 47% after six months, the vaccine remains 90% effective against the risk of hospitalization.
Two doses of the Pfizer/BioNTech vaccine are effective against hospitalization risks associated with Covid-19 and all of its variants for at least six months, notes a study published Tuesday, October 5 in the journal. scalpelConfirming previous estimates.
The study by Pfizer and the US health network Kaiser Permanente analyzed the medical data of 3.4 million people in Southern California between December 4, 2020 and August 8, 2021. The vaccine’s effectiveness against infection risks appears to decrease over time, from 88% in the month following the second dose injection to 47% after six months. On the other hand, the vaccine remains 90% effective against the risks of hospitalization associated with Covid-19, including in the case of the delta variant, for at least six months, she asserts.
These findings confirm the results of previous estimates from the US Centers for Disease Control and Prevention (CDC) and the Israeli Ministry of Health, he points out. scalpel In a press release. “Our study confirms that vaccines are a central tool in epidemic control and remain highly effective in preventing acute forms and hospitalizations, including against delta or other variants of concern.”Sarah Tartouf, lead author of the study, summarized in the press release for Lancet.
“A specific analysis of the variants clearly shows that the vaccine is effective against all types of variants. People with Covid-19 who received two doses of the vaccine often became infected because the vaccine lost efficacy over time and not because this or that variant escapes the protection of the vaccine. The vaccine”, said Louis Godard, vice president and medical director of Pfizer Inc.
The researchers recognize some biases in their survey: For example, they had no data on respect for mask-wearing, social interactions, or occupation of the population studied, which could have had an impact on the likelihood of contracting Covid. -19 . According to the study authors, these findings demonstrate the importance of expanding global immunization and analyzing vaccine efficacy over time to determine which populations should prioritize booster doses.