As Italy seeks to speed up its vaccination campaign, health authorities are considering giving people who have recently recovered from Covid-19 a single shot of one of the three vaccines currently in use, which usually require a double dose.
The health ministry’s director of prevention, Giovanni Rezza, signed off on the idea in a new circular issued on Wednesday, while cautioning that it could be withdrawn if any of the new variants emerging are found to present a high risk of reinfection.
A single dose is being considered for people who tested positive for the new coronavirus at least three months earlier, but preferably no more than six months ago, the circular states.
It would not apply to people with weakened immune systems, who would continue to receive both doses.
The proposal does not mean that people who have had Covid-19 would skip to the front of the queue or be specially summoned to get vaccinated.
Instead, as and when they become eligible according to Italy’s vaccine priority list, they should inform the local health authorities and ideally provide evidence of when they were infected, for example a positive PCR test result. Health services already ask people if they have had Covid-19 on the consent forms they fill out before getting their shot.
The health ministry does not advise carrying out blood tests to check for antibodies, which medical experts do not consider a foolproof way of identifying who has previously been infected.
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Early studies have indicated that people who have already fought off Covid-19 can have a strong immune response after only the first dose of the Moderna or Pfizer-BioNTech vaccines, with the shot acting as a kind of booster to the antibodies they have already developed. In some cases, researchers say, these people show higher immunity after just one dose than people who have never been infected achieve after two.
But some experts caution that more research is needed to investigate how long the antibodies last and whether they are effective against new variants of the virus.
With more than 2.4 million people in Italy known to have recovered from Covid-19, giving only one shot could save much needed supplies as Italy struggles to keep up with its vaccination timetable.
The new government has said it will make speeding up the campaign a top priority, announcing a target this week to increase the number of vaccination centres and deliver a total of 56 million doses by June.
Around 4.8 million have been administered to date, just over two months into the programme.
The Johnson & Johnson vaccine, which requires just one dose for full protection, has not yet been approved for use in the European Union.