A student in Bogor, Indonesia, receives a Sinovac vaccine as part of a COVID-19 vaccination campaign for schoolchildren aged 12 to 18.Credit: Adriana Adie / NurPhoto / Getty

At a time when much of the world still struggles to access COVID vaccines, the question of whether to immunize children can seem like a privilege. On July 19, vaccine advisers in the UK recommended delaying vaccines for most young people under 16, citing very low rates of severe illness in this age group. But several countries, including the United States and Israel, have moved forward, and others hope to follow suit when supplies allow.

Nature examines where the evidence is on children and COVID vaccines.

Is it necessary?

From the early days of the pandemic, parents have been reassured that SARS-CoV-2 is much less likely to cause serious illness in children than in adults.

But some children still get very sick, and the specter of a long COVID – a constellation of sometimes debilitating symptoms that can linger for months after even a mild COVID-19 attack – is enough for many pediatricians to urge vaccination on them. as quickly as possible. “I spent the pandemic caring for children in a children’s hospital,” says Adam Ratner, a pediatric infectious disease specialist at New York University. “We didn’t see as many as on the adult side, but a lot of kids who were pretty sick.”

Vaccination advisers in the UK, however, have recommended that only clinically vulnerable adolescents or living with vulnerable adults be vaccinated at this time. Serious illnesses, deaths and even long-lasting COVIDs are rare in healthy adolescents and children, and almost all vulnerable adults will soon have received two doses of the vaccine, the University of Bristol pediatrician said, Adam Finn, to reporters at a press briefing.

But in some countries, little is still known about how COVID affects children. Some official counts of hospitalizations and deaths from COVID in sub-Saharan Africa, for example, do not disaggregate cases by age. As a result, pediatricians are uncertain what deaths have occurred in children and youth, and how COVID results might be affected by conditions such as malnutrition, tuberculosis, or concomitant HIV infection. “We feel in the dark,” says Nadia Sam-Agudu, a pediatrician at the University of Maryland School of Medicine in Baltimore who works in Nigeria.

Additionally, some pediatricians are concerned about what will happen to children co-infected with SARS-CoV-2 and other common viruses, such as respiratory syncytial virus, which is one of the causes of the common cold but can sometimes cause more severe respiratory illness in young children. Strict closures have kept this problem at bay in some areas, but as social distancing measures are relaxed, there are already signs that respiratory syncytial virus infections in children are on the rise, says Danilo Buonsenso, pediatrician. at the Gemelli University Hospital in Rome. “We don’t yet know what the burden of co-infections in children will be when we have massive circulation of routine viruses and COVID,” he says.

Is childhood immunization safe?

A handful of vaccines have been tested in young people over the age of 12, including mRNA vaccines made by Moderna and Pfizer-BioNTech, and two Chinese vaccines made by Sinovac and Sinopharm. And several countries, including the United States, Israel and China, now offer vaccines to this age group. More studies should report results in young people over 12 soon, including studies on the Zydus Cadila vaccine and the inactivated coronavirus vaccine Covaxin, both made in India.

So far, vaccines appear to be safe in adolescents1 , and some companies have switched to performing clinical trials in children as young as 6 months old. In the United States, vaccines for those under 12 may be available later this year, according to pediatrician Andrea Shane of Emory University in Atlanta, Georgia.

A potential link between the Pfizer vaccine and heart inflammation – conditions called myocarditis and pericarditis – has emerged since Israel and the United States began vaccinating young people. However, researchers have not yet established that the vaccine caused the inflammation. Most of those affected have recovered and data suggests that the risk of these conditions is “extremely low,” says pediatrician David Pace of the University of Malta in Msida – in the range of around 67 cases per million. second doses in adolescent males aged 12-17, and 9 per million in adolescent girls of the same age group.

How will immunization of children and youth affect the pandemic?

Malta has fully vaccinated 80% of its population – one of the highest vaccination rates in the world – and now also vaccinates adolescents over 12 years old. There, the decision to vaccinate young people was shaped, among other factors, by the proximity of tight-knit family structures in a country where adolescents often have frequent contact with their grandparents, Pace says. “At the population level, vaccinated adolescents can reduce transmission to vulnerable older people,” he says. Young Maltese also often travel abroad for their studies, potentially importing coronavirus infections and variants from abroad, he adds.

Data shows that children and especially adolescents can play an important role in the transmission of coronaviruses, explains Catherine Bennett, epidemiologist at Deakin University in Melbourne, Australia. And concerns about transmission from children and adolescents are increasing as new variants of the coronavirus emerge. It’s possible that more transmissible variants will develop a way to cross a youngster’s immune response that makes them more resistant to infection, Bennett says, which makes it all the more important that they be vaccinated.

Hopes of obtaining herd immunity through vaccination have waned, so countries must do their best to keep transmission low, she adds: “You only need a bad population. vaccinated to generate global variants. ”

Is Childhood Immunization Fair?

Chile, another country with one of the highest COVID vaccination rates in the world, is also rolling out vaccines for people aged 12 and older.

But Miguel O’Ryan, a former member of two government advisory committees who pushed for aggressive vaccination campaigns, is now wondering if it’s time to slow down. “Countries probably shouldn’t move forward with pediatric vaccinations so quickly,” says O’Ryan, a pediatric infectious disease specialist at the University of Chile in Santiago. “Other countries, even our neighbors, are struggling very hard to get enough vaccines for their high-risk groups. “

O’Ryan isn’t the only one worried about the use of valuable vaccines to immunize children, as more vulnerable populations around the world still struggle to get supplies. In May, the head of the World Health Organization, Tedros Adhanom Ghebreyesus, said richer countries that immunize children do so at the expense of health workers and high-risk groups in other countries. But advocates for immunization of children and young adults argue that either need not be the case. “It’s kind of a false dichotomy,” Ratner says. Sam-Agudu agrees, pointing out that some rich countries have bought more than enough doses to fully immunize their populations. “The argument for sending vaccines out of the country should not preclude immunizing children in higher income countries,” she said.

And there are other steps that could be taken to improve vaccine supplies to countries in need, Bennett says. More could be done to better target donations, she notes. For example, rather than allocating vaccine doses given to countries based solely on the number of people living there, they could be distributed based on other factors, such as the need to preserve health services in the face of a crisis. upcoming malaria season, or current measles epidemic. “We probably haven’t yet had the in-depth epidemiological war room we need to map the problem and how best to solve it,” she says. “There’s a whole range of ways to look at it. “

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