The Haut Autorité de Santé on Friday released an opinion that said that people who had previously been infected with Covid-19 develop an immune response similar to that bestowed by a vaccine dose, and that a single dose after infection would likely suffice.
— Haute Autorité de santé (@HAS_sante) February 12, 2021
The HAS is an advisory body, so the government now needs to decide whether to incorporate this advice into its official vaccine policy.
All three Covid-19 vaccines approved for use in France – Pfizer BioNTech, Moderna and AstraZeneca – are administered in the form of two doses, delivered several weeks apart.
This is because clinical trials showed that immunity against the disease was significantly higher after individuals received two shots.
The HAS's published opinion said: “A single vaccine dose will also play the role of reminding” the patient's immune system how to fight Covid-19.
The authority recommended a gap of between three and six months after infection before individuals who had recovered from Covid-19 receive a jab.
“At the moment no country has clearly positioned itself in terms of a sole vaccination dose for people who have already contracted Covid-19,” it said.
France has accelerated its vaccination programme in recent weeks but it is still in its infancy.
As of Thursday, over 2.1 million people had received at least one vaccine dose, with almost 535,800 having already received two. France has decided that it will not delay the gap between the first and second dose beyond the manufacturer's recommendation of between three and four weeks, as some countries have done.
At least 3.4 million people have had confirmed Covid-19 infections in France, although there are likely to have been far more given the relative lack of accessible testing during the pandemic's first wave.
Two recent US studies suggest that a single vaccine dose may work in individuals who have already recovered from Covid-19.
One paper said that immunity in individuals who had had Covid-19 and then received a single vaccine dose “is equal to or even exceeds” that of people who have not had Covid-19 but received two vaccine doses.
A vaccine still in development by Johnson & Johnson works with a single dose, but it is yet to receive emergency use authorisation from EU and US regulators.