US approves Pfizer and Moderna vaccines for youngest children

The US Food and Drug Administration has approved emergency use of Pfizer and Moderna COVID-19 vaccines for the youngest children, the last age group to receive immunization in most countries.

Moderna’s two-dose vaccine for children aged six months to five years was approved, as were Pfizer’s three doses for children aged six months to four years.

The agency authorised Moderna’s two-dose vaccine for children aged six months to five years, and three doses of Pfizer’s shots for those between six months and four years old.

“Many parents, caregivers and clinicians have been waiting for a vaccine for younger children and this action will help protect those down to six months of age,” Food and Drug Administration chief Robert Califf said in a statement.

“We expect that the vaccines for younger children will provide protection from the most severe outcomes of COVID-19, such as hospitalisation and death.”

Before the vaccines can be used, the Centers for Disease Control and Prevention (CDC) must also recommend them – a final green light that will be given following a meeting of an advisory committee of experts.

US officials have said that if the FDA gives its approval, 10 million doses will be sent around the country immediately, followed by millions more in weeks to come.

Each of these vaccines is based on messenger RNA, which boosts the immune system by delivering the genetic code for the coronavirus spike protein to human cells, which then grow it on their surfaces.

The vaccines were tested in trials of thousands of children. They were found to cause similar levels of mild side effects as in older age groups and triggered similar levels of antibodies.

Efficacy against infection was higher for Pfizer, with the company placing it at 80 percent, compared to Moderna’s estimates of 51 percent for children aged six-months to two years old and 37 percent for those aged two to five years.

But the Pfizer figure is based on very few cases and is thus considered preliminary. It also takes three doses to achieve its protection, with the third shot given eight weeks after the second, which is given three weeks after the first.

Moderna’s vaccine should provide strong protection against severe disease after two doses, given four weeks apart, and the company is studying adding a booster that would raise efficacy levels against mild disease.

However, Moderna’s decision to go with a higher dose is associated with higher levels of fevers in reaction to the vaccine compared to Pfizer.

There are some 20 million children aged four years and under in the United States.