France’s top health advisory body, The Haute Autorite de la Sante (HAS), recommended on Friday that recipients of a first dose of the AstraZeneca shot who are under 55 should receive a second dose with a so-called messenger RNA vaccine.
The French decision came after the European drug regulator said on Wednesday there was a possible link between AstraZeneca’s Covid-19 shot and a very small number of cases of rare blood clots.
HAS provides analysis, recommendations, and measures for improvement in matters of health and medicine said it based its suggestion on scientific rationale called ‘heterologous prime-boost’ which uses a two-step vaccination scheme: It uses an entirely different technique from the first (prime) for the second injection (boost). HAS said such techniques have been effective in HIV vaccines.
HAS recommended completing the vaccination schedule for people under 55 who had the first dose of AstraZeneca with an mRNA vaccine within 12 weeks after the first injection.
Two mRNA vaccines, one from Pfizer and BioNTech and one from Moderna, have been approved for use in France.
The mRNA vaccine prompts the human body to make a protein that mimics part of the virus, triggering an immune response, while AstraZeneca’s shot uses a harmless, weakened version of a chimpanzee common-cold virus to generate an immune response and prevent infection.
France resumed administration of the AstraZeneca vaccine shortly after the European Medicines Agency and the World Health Organization okayed the use of the vaccine.
Many European countries have temporarily suspended the use of the AstraZeneca vaccine last month after reports that it could cause blood clots.
Most of the European countries resumed the use of Astra Zeneca after European Medicines Agency concluded that the benefits of the vaccine outweigh its risks.