This news was immediately hailed by President Joe Biden as "a monumental step in the fight against the virus".

“These vaccines are safe and highly effective, and will give parents peace of mind knowing their child is protected against the most severe cases of Covid-19,” he added in a statement.

On Friday, the American Medicines Agency (FDA) had already authorized them urgently for these young children – who so far could not be vaccinated before 5 years old.

But the Centers for Disease Prevention and Control (CDC), the country's main health agency, still had to recommend them so that the injections could begin, which has now been done.

"We know that millions of parents (...) want to have their young children vaccinated, and with today's decision, they can," said CDC director Rochelle Walensky in a statement.

The US government has made available to States several million of these infant doses, and had already begun to send them to the four corners of the country as soon as the FDA authorization was issued.

Joe Biden promised that parents could start making appointments next week to perform the first shots, and that vaccines would be available in thousands of places, including pharmacies and hospitals.

Pfizer in three doses

Moderna's vaccine, in two doses given one month apart, is now available for children between six months and 5 years old at a reduced dosage of 25 micrograms (compared to 50 micrograms for 6-11 year olds, and 100 for 12-17 year olds, like adults).

The Pfizer-BioNTech vaccine is authorized between six months and 4 years at the rate of 3 micrograms per injection, or one tenth of the dosage used for adults.

Main difference: it will have to be done from the outset in three doses – the first two at three week intervals, the third administered eight weeks after the second.

Children receiving it will therefore not be optimally protected for several months.

But its side effects appeared in clinical trials to be less severe than after Moderna's vaccine.

About a quarter of young children given Moderna developed a fever, especially after the second dose.

But it usually subsided after a day.

The United States has approximately 20 million children under the age of five.

Even if the youngest are less vulnerable to Covid-19, some 480 children in this age group have nevertheless died in the country.

They can also develop long Covid, or severe cases of pediatric multisystem inflammatory syndrome.

Pfizer said it wanted to file an application for authorization for this age group with the European Medicines Agency (EMA) "in early July".

© 2022 AFP