A third dose of the Covid-19 vaccine from Pfizer Inc and BioNTech produced significant protection against the Omicron variant of the coronavirus in healthy children ages five to 11, the companies said on Thursday.
Blood serum analysis of 30 paediatric participants who received a booster dose in a study showed a 36-fold increase in Omicron neutralising antibodies, the drugmakers said.
Neutralising antibodies against the original version of the virus for which the vaccine was designed rose six-fold following the booster shot.
The companies said they plan to apply for US emergency use authorisation of a booster dose for the age group in coming days, with additional submissions to global regulatory agencies including the European Medicines Agency to follow.
The mid- to late-stage study was testing the safety and immunogenicity of a 10-microgram booster dose in 140 healthy children aged five through 11 years. Adults receive a 30-microgram does of the vaccine.
It is unclear how much demand there is for a third vaccine dose in the age group. Just 28% of children in the age group – around 8 million – are fully vaccinated, according to data from the US Centers for Disease Control and Prevention.
Health experts called the data “promising” but cautioned that the study size was very small and said there was need for more data to understand the extent to which this booster prevents severe illness and hospitalisation in children, and how it will fare against future variants.
“So overall, (the data) is very positive. But it also raises a number of questions. How durable will the response be? How well will it hold up to the future variants?” said Dr Anna Bershteyn of NYU Langone Health.
There has been some scepticism on need for boosters in younger children given the reduced risk of severe infection and hospitalisation in the age group.
Still, Dr Scott Hadland, chief of adolescent medicine at Mass General Hospital for Children, said many parents have been asking for them.
“What we keep finding with the pandemic is that when we make available vaccines and boosters, even when they don’t offer perfect protection against infection, they often are very protective against severe illness and hospitalisation,” Hadland told Reuters.
Earlier this year, the US Food & Drug Administration authorised a third dose of the vaccine for children ages 12 to 15 and those aged five through 11 who are immunocompromised.
The agency at the time said it will weigh boosters for five- to 11-year olds after more children have received two doses.