The European Medicines Agency (EMA) on Monday authorized the use of a booster dose with the Pfizer vaccine for all adults, six months after the previous one. In France, the opinion of the HAS is expected this Wednesday.
- The objective of this booster dose is to boost the level of antibodies and therefore the immunity which would decrease over time, especially against infections.
- The European Agency nevertheless indicates that it lacks data concerning the safety of the booster dose, but the signals indicate side effects similar to those felt after the second injection.
- A study published on Monday in the journal The Lancet confirmed that the Pfizer vaccine is still effective six months after the two injections.
Top start in Europe for booster doses? This Monday, the European Medicines Agency (EMA) has approved the injection of a third dose with the Pfizer vaccine for all adults, provided that this is done at least six months after the previous one. The people “whose immune system is severely weakened“can be given this dose”at least 28 days after their second dose”, specifies the Agency. Regarding Moderna, the other messenger RNA vaccine administered in Europe, the evaluation is still ongoing but it is likely that the end result will be the same.
A lack of safety data
The objective of this booster dose is to boost the level of antibodies and therefore the immunity which would decrease over time, especially against infections. The EMA relies on data showing an increase in the level of antibodies in 18-55 year olds when this booster dose is inoculated within this period. These figures include those from the general population in Israel, the first country to launch a third dose campaign this summer. These highlighted the significant increase in the concentration of neutralizing antibodies after the booster, while revealing a gradual decline in vaccine efficacy over time, favored by the emergence of the Delta variant.
The European Agency nevertheless indicates that it lacks data concerning the safety of the booster dose. It only has the Israeli example as well as those following the first injections in the United States and France which seem to show that the third injection does not cause more side effects than the second. Data live studies involving 22,000 people found that commonly reported side effects mainly included pain at the injection site (71% of study participants), fatigue (56%) and headache (43%).
HAS opinion expected on Wednesday
Following this announcement, it is now up to the public health authorities of the countries to decide. In France, the opinion of the High Authority for Health (HAS) is expected for this Wednesday. Last August, it positioned itself in favor of the administration of a third dose for people over 65 and for those who suffer from severe comorbidities. The Ministry of Health then followed this advice and the booster vaccination campaign began on 1er last September.
Pfizer still effective six months later
A study published this Monday in the journal The Lancet confirmed that the Pfizer vaccine is still effective six months after the two injections. This is based on the analysis of medical data from 3.4 million people in Southern California collected between December 4, 2020 and August 8, 2021. The vaccine shows 90% effectiveness against the risk of hospitalization six months later, including in the event of infection with the Delta variant. “Our study confirms that vaccines are a central tool to control the epidemic and remain extremely effective in preventing severe forms and hospitalizations, including against Delta or other variants of concern”, assures Sara Tartof, lead author of the study. However, it appears that after six months, the protection against contamination conferred by the Pfizer vaccine drops from 88% to 47%.
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