Did we need any more proof? Well, apparently yes, or at least some do. A French study of 22.6 million people vaccinated against Covid-19 found a 90% reduction in serious illness and death.
More striking, all study participants were over the age of 50. Results were taken from the 14th day after patients had received their second dose.
It’s worth noting that an epidemiological study of this kind can hardly get much larger than 22 million people, given that each vaccinated participant has to be paired with someone who is not vaccinated to compare outcomes.
In the vaccinated cohort, 53% had been vaccinated with the Pfizer Cominarty vaccine. Just under 40% had received the AstraZeneca vaccine. The rest received the Moderna shot.
Interestingly, the study included a follow-up period of five months. Though results over a longer period than this remain desirable, it was good to see that vaccine efficacy did not decline during this five-month period (as measured in the number of cases of serious illness and death).
The result will add to doubts about the necessity of a mass-booster campaign, especially given the still-low vaccination rates outside the most developed countries.
Researchers also isolated data from participants during the 20 June to 20 July period, in order to examine any change brought by the emergence of the coronavirus delta variant. They found that efficacy in preventing serious illness and death remained at 92% for the 50 to 74 year-olds, and only dropped to 84% for those aged 75 years or more.
However, the leader of the study, Mahmoud Zureik, told AFP that this one-month time period was too short to be definitive, and that the release of data from ongoing studies would provide a more certain picture.
“In conclusion, all Covid-19 vaccines are highly effective and have a major effect on reducing the risk of severe forms of Covid-19 in people aged 50 and over in France in real life,” said the study authors. “Continued monitoring…will make it possible to measure the evolution of efficacy over a longer period and to better characterize the effects of the Delta variant.”
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