A single dose of the Pfizer Covid-19 vaccine can reduce infections among children, a new study suggests.
And if a child contracts Covid-19 after being vaccinated, they are “likely to have milder disease”, said researchers from King’s College London and ZOE Ltd.
While COVID-19 vaccines have been shown to prevent serious illness and death, questions have been raised about their ability to reduce the spread of infection.
The latest study examined the effectiveness of a single dose of the Pfizer/BioNTech Covid vaccine in children.
The researchers examined information on 115,775 children ages 12 to 17 through the Covid Symptom Study app.
They analyzed data between August 5, 2021 and February 14 this year, meaning the study looked at the effectiveness of the jab as different variants took the UK by storm.
Of the children who participated in the study, 25,971 received a dose of the vaccine.
The experts found that the chance of becoming infected with the Omicron variant, the one widely circulating in the UK at the moment, was reduced by 53.7% between 14 and 30 days after vaccination.
This increased to a reduced risk of infection of 63.7% from 61 to 90 days after injection, according to the preliminary study, published today on MedRxiv.
The researchers said children were more likely to dodge Covid after being vaccinated if they had previously contracted Covid-19.
They said vaccinated children and youth who contracted Covid during the wave of Delta infections had milder illness than unvaccinated children.
But during the Omicron wave this was only evident in 12- to 15-year-olds, and not in the 16- and 17-year-olds who participated in the study.
Lead author of the study, Professor Emma Duncan from King’s College London, said: “Our article will provide useful information for parents considering having their children vaccinated against Sars-Cov-2.
“Even a single dose of the Pfizer vaccine means that children and young people are less likely to contract Covid-19 and, if they become infected after vaccination, they are likely to have a milder course of illness, at least for Delta and Omicron variants.
“Our article also reassures that Omicron in children is usually mild, even in unvaccinated children.”
Many parents will weigh whether or not to accept the offer of a vaccine for healthy children aged five and over, which will be launched in a matter of days in Scotland and from April in England.
Children in Northern Ireland and Wales can now pre-order their vaccine.