Washington, Feb 2 (IANS): US drugmaker Pfizer has applied to the Food and Drug Administration (FDA) to authorise two doses of their Covid vaccine for children younger than five years, the media reported.

Although a clinical trial among children in the age group of 2 to 4 years in December showed that two doses failed to produce the hoped-for immune response, the federal regulators pressed the company to submit the request, the New York Times reported.

The request for emergency authorisation comes as the highly contagious Omicron variant has led to record numbers of infections. The under-5 group includes more than 19 million children -- the only Americans not yet eligible for vaccination.

The disappointing trial results also prompted Pfizer to test a third low dose of the shot in that age group.

While the results are expected at the end of March, federal regulators have encouraged Pfizer to apply for authorisation of a two-dose regimen now, the report said.

In the trial, only children between 6 months and 2 years old demonstrated an immune response comparable to that of older teenagers and young adults.

But, in meetings about the strategy, government officials argued that two doses had proved safe, even if they failed to produce an immune response in the whole age group, according to multiple people familiar with the discussions.

Children in the trial received one-tenth of the adult dose.

If children can get an initial injection this month, some officials reasoned, they will be ready for a third dose by the time researchers get what they hope will be successful results from the three-dose trial. The first two doses would be spaced three weeks apart, followed by a third dose two months after the second.

It was important to act quickly given the surge in Omicron cases, which has now peaked in many parts of the country, and the likelihood that other variants would follow, Dr. Janet Woodcock, the acting FDA commissioner, and Dr. Peter Marks, an agency regulator who oversees its vaccines office, were quoted as saying on Tuesday.