Pfizer vaccine safe and effective for children aged six months to four years, FDA says

Pfizer’s three-dose Covid vaccine for babies and toddlers is safe and effective, US health authorities claim.

Pfizer’s three-dose Covid vaccine for babies and toddlers is safe and effective, US health authorities claim.

The Food and Drug Administration on Sunday released its analysis of Pfizer’s emergency use authorisation application to expand its vaccine to children aged six months to four years old, ahead of a crucial meeting on Wednesday where an independent panel of experts will vote on the request.

The Vaccines and Related Biological Products Advisory Committee Meeting on Wednesday will also consider whether to approve Moderna’s under-fives vaccine, which the FDA said Friday was safe and effective based on its analysis of data submitted by the company.

The FDA typically accepts the recommendation of the panel. If approved, the vaccines could be available to around 19 million additional children from next week.

Surveys show fewer than one in five parents of children under five in the US are eager to get their children vaccinated immediately.

Around four in 10 say they plan to wait and see how the vaccine is working for others, while 27 per cent say they will “definitely not” get their child vaccinated.

“Available data support the effectiveness of the Pfizer-BioNTech Covid-19 Vaccine three-dose primary series in preventing Covid-19 in the age group of six months through four years,” the FDA said.

Pfizer’s data was based on a study of 4526 children, two thirds of whom received the three-microgram injection – originally two doses, later increased to three doses, three weeks apart – with the remaining third given a placebo.

Out of the entire study group, there were only 10 cases of symptomatic Covid reported.

Among children aged six to 23 months, there were three cases – one in the vaccine group and two in the placebo.

In the two to four age group, there were seven total cases – two in the vaccine group and five in the placebo.

The FDA meets this week to consider Pfizer and Moderna’s vaccines for under-fives. Picture: Menahem Kahana/AFP

This translates to an overall effectiveness of 80.4 per cent, according to Pfizer.

In the younger group that figure was 75.6 per cent, and 82.4 per cent in the older group.

The FDA cautioned that “definitive conclusions” about the effectiveness of the three-dose series were limited by the “small number of cases”.

But the regulator said neutralising antibody tests showed the vaccine generated an immune response at least as strong as observed in young adults, its main requirement for effectiveness.

No serious adverse reactions were linked to the vaccine, according to the FDA and Pfizer.

The most commonly reported reactions among the younger group were irritability, drowsiness, reduced appetite and tenderness at the injection site. Among the older group, the most commonly reported reactions were pain at the injection site, fatigue and injection site redness.

Most reactions were “mild to moderate in severity” and typically lasted one to two days.

There were no reported cases of myocarditis or pericarditis among the test participants, but the FDA acknowledged the sample size was too small to quantify the frequency of the uncommon reaction in this age group.

The FDA conceded that while heart inflammation, which is seen most commonly among young males aged 16 to 17, typically involved “rapid resolution of symptoms”, the “long-term sequelae of vaccine-associated myocarditis, if any, remain to be determined”.

“The risk of vaccine-associated myocarditis/pericarditis among children six months through four years of age is unknown at this time,” it said.

The FDA stressed the need for a vaccine in young children given the “uncertainty” of the pandemic.

“Among infants and children six months through four years of age, rates of hospitalisation and death due to Covid-19 are higher than among children and adolescents five to 17 years of age, and comparable to individuals 18-25 years of age, underscoring the benefit of an effective Covid-19 vaccine in this age group,” it said.

Young children account for 0.02 per cent of Covid deaths in the US. Picture: Rogelio Figueroa/AFP

Of the approximately 84 million Covid cases reported in the US to date, 3.3 per cent were among children aged zero to four.

One million deaths have been attributed to Covid, according to the Centers for Disease Control and Prevention (CDC), with 202 among children in this age group – or just 0.02 per cent.

From December 2021 to May 2022, when Omicron was predominant, there were 535 children aged six months to four years admitted to intensive care.

The document notes that among children in this age group with Covid-associated hospitalisation, half had one or more underlying conditions – most commonly obesity, which was also associated with increased risk of severe disease.

Last week, the FDA said data from clinical trials conducted by Moderna suggested its vaccine efficacy against symptomatic Covid was 51 per cent in babies aged six months to two years old, and 37 per cent in children aged two to five.

The figures are lower than those recorded during clinical trials on adults, but that is only because the trials for the very young children were conducted during a wave linked to the Omicron variant, according to the FDA.

“Although the VE (vaccine efficacy) … in children six months to five years is lower than that observed in the pivotal adult or older paediatric studies, it is highly consistent with real-world vaccine effectiveness observed against Omicron in adults,” the FDA said in a statement.

Even though Moderna’s vaccine has proven less effective against the Omicron variant, it remains very good at protecting against severe cases of the disease, the FDA pointed out.

That is why the FDA concluded that the Moderna data “support the administration” of the vaccine in two doses of 100 micrograms each in adolescents aged 12 to 17, 50 micrograms for six to 11 year olds, and 25 micrograms in children aged six months to five years.

In the United States, Moderna’s vaccine is currently only authorised for people aged 18 and older.

— with AFP

Originally published as Pfizer vaccine safe and effective for children aged six months to four years, FDA says