Health Minister Oliver Véran said there is "no consensus in the scientific community" that doubling the time between the two doses is risk-free.
French authorities have decided to shelve plans to double the time in between COVID-19 vaccinations due to a "lack of scientific consensus".
Health Minister Oliver Véran made the announcement in a midday press conference on Tuesday in which he said that although some experts have backed lengthening the time between the two doses in order to give a first dose to as many people as quickly as possible, "there is no consensus in the scientific community on this proposal at this stage."
"And according to some experts this would not be a risk-free proposal," he added.
The time between the two doses of the Pfizer/BioNtech vaccine will thus be maintained at 21 to 28 days.
Alain Fisher, president of the scientific committee advising the government on vaccines, says the effects of a longer gap between injections remain unclear and the first shot only provides limited immunity.
He flagged for instance that data from Israel suggested that the level of protection between the two doses in people over the age of 60 currently stand at around 33 per cent — lower than the 50 per cent found in clinical studies.
He also said that data suggested that the first dose only led triggered "a low level of antibodies" and that it "is only after the second dose that a clear increase in the level of neutralizing antibodies is observed."
In early January, French Prime Minister Jean Castex had announced extending the time between shots to six weeks to allow more people to get the initial shot.
The latest decision, Véran said, means that fewer people will receive a first dose of the vaccine in February, with most doses going towards administering second doses.
France has so far administered nearly 1.01 million doses of the vaccine, according to the latest official figures.
The country has registered 3.1 million cases and reported 614 new deaths Tuesday, bringing the total at least 74,250 confirmed deaths.