In May 2021, Judith Guzman-Cottrill found herself facing a difficult decision. A paediatric infectious diseases physician at Oregon Health & bet365体育赛事 University, she had just identified some of the earliest cases of myocarditis in adolescents who had received a Covid-19 vaccine.

The news was particularly concerning, as Guzman-Cottrill’s own 13 year old daughter had just become eligible to receive a vaccination herself. “The first case at our hospital was in late April,” she says. “But in May, I began to hear about a few more cases from infectious disease colleagues across the country. My daughter has a history of autoimmune illnesses, and I had to make a decision about her vaccine, so I was thinking about this from the doctor’s standpoint, and also as a parent.”

She set up a Zoom call with her colleagues, who had all witnessed the same trend – a small handful of otherwise healthy adolescent boys, aged 14-19, who developed sudden chest pains within a few days of their second vaccine dose.

But while these findings provoked some concern, Guzman-Cottrill’s experience of treating children over the past 18 months meant she still concluded that the protective benefits of vaccination far outweighed any potential risks. After careful consideration, she agreed to let her daughter have the jab. “I've been taking care of children who have been hospitalised with Covid-19 since the beginning of the pandemic,” she says. “And the numbers are much lower than adults, but it's certainly not zero.”

In a microcosm, Guzman-Cottrill’s dilemma encapsulates the one currently being faced by the UK’s Joint Committee on Vaccination and Immunisation (JCVI). Right now only children deemed particularly vulnerable to Covid-19 – for example those with severe neurological impairments – are eligible for a vaccine, but with increasing numbers of nations across Europe rolling out vaccines to those aged 12 and over, the regulator is coming under pressure to follow suit.

Reports suggest that 20 European countries are either currently vaccinating 12-18 year olds or planning to do so in the very near future, alongside the UAE, Israel, Japan, Singapore, US, China, Canada, and the Philippines. “The recommendations are made by immunisation committees in each of these countries,” says Beate Kampmann, director of the Vaccine Centre at the London School of Hygiene & Tropical Medicine. “It's driven by the dynamics of the epidemic in that country, political pressure and vaccine supply. The US has got tons of vaccines, so they have the ability to downscale the ages very quickly.”

As well as protecting children themselves from the Sars-CoV-2 virus, one of the main goals of extending the vaccination campaign to younger age groups is to break transmission chains within households and schools. The sheer contagiousness of the new Delta variant means scientists are concerned that children could spread it to elderly relatives who may have not mounted a full immune response to their own vaccine, leaving them vulnerable. There have already been cases of so-called vaccine breakthrough infections - where fully vaccinated people become infected again with Covid-19 - in over 50s, suggesting that their immune response has waned.

There is already evidence in some countries who have already rolled out the vaccine to younger age groups, that this can help lower transmission rates. In Israel, who began vaccinating 16-18 year olds last December, infection rates have plummeted from 559 cases per 100,000 people in mid January, to 1.5 per 100,000 today, with rates also dropping in unvaccinated children.

“Now we have this Delta variant, I think we're definitely going to be seeing an increase in transmission this coming autumn and winter, as kids go back to the classroom,” says Guzman-Cottrill. “I see it as kind of a race against the calendar to vaccinate children before then, when seasons change and everyone goes back indoors.”

But while vaccines remain society’s most powerful defensive weapon against the coronavirus, other scientists emphasise that the risk/benefit ratio of inoculating the young does need to be carefully assessed. Children’s bodies are sensitive, and differ at varying stages of development, meaning the jabs may need to be adapted to suit their needs. In particular, the juvenile immune system can react more vigorously to vaccines, leading to side effects which may not be present in adults. It is this which is thought to be behind the cases of heart inflammation, and as a result some scientists have broached the idea of either giving children only one shot instead of two or reducing the dose. However so far, neither concept has been thoroughly tested.

“The younger you are, the higher chance you have of having more reactogenicity to the vaccine,” says Guzman-Cottrill. “So more fever, more chills, more muscle aches, as well as other side effects.”

As a result, the JCVI has been cautiously observing the safety data emerging from around the world as other countries roll out the vaccine in 12-18 year olds, before coming to its own decision. “You need to take safety extremely, extremely seriously to make sure that there isn't anything else untoward emerging,” Kampmann says. “Until we've got a safety database that is sufficient for JCVI, for making informed recommendations, it is also a question of prioritisation, which is why planning the booster shots campaign took precedence over organising anything for the children.”

Most of the safety data we have on how the vaccine performs in children comes from the US where the Pfizer vaccine was approved for use in 16-18 year olds last December, before being rolled out to 12-15 year olds in May. Sonja Rasmussen, professor of paediatrics and epidemiology at the University of Florida, is adamant that the benefit outweighs any risks of vaccine side effects, pointing to how the proportion of Covid-19 cases in children have risen in recent months.

“We know kids aren't as severely affected by Covid-19 as adults, but that doesn't mean they don't have any effect,” she says. “Over 300 kids have died in the US since Covid started, and a lot have been hospitalised. Now the proportion of new infections that are made up by kids is increasing a lot, from about two per cent in March 2020, to around 24 per cent at the moment.”

So far the US Centers for Disease Control and Prevention (CDC) has confirmed 594 cases of vaccine-related myocarditis in under 30s, including 12-18 year olds, but Rasmussen points out that the incidence remains very rare. More than six million 12-18 year olds across the US have now received the vaccine, and most myocarditis cases rapidly resolve after a few days of anti-inflammatory treatment. A recent analysis from the CDC also estimated that for every million second dose vaccinations of children aged 12-17 over 120 days, there are somewhere between 64 and 79 cases of myocarditis. But these vaccinations prevent an estimated 14,200 cases of Covid-19, which would normally result in 398 hospitalisations, 109 intensive care admissions, and 3 deaths.

“I think for kids above the age of 12, we have really good data right now that the benefit of the vaccine is worth the risk,” says Rasmussen. “I do think right now parents need to be thinking, ‘Do I want my kid to get the vaccine? Or do I want my kid to get Covid-19?’”

While children are less vulnerable to Covid-19 than adults, there are some very real risks. It is hoped that vaccinations will protect children from Multisystem Inflammatory Syndrome (MIS-C), a serious condition which begins a few weeks after an acute Covid-19 infection, and affects around 1 in 5,000 children, particularly people from Black, Asian or ethnic minority backgrounds. There is also increasing evidence that children of all ages are vulnerable to Long Covid. John Warner, a professor of paediatrics at Imperial College, London, has been working with the StopCOVID Research Team at Sechenov First Moscow State Medical University on a study attempting to assess the prevalsence of Long Covid in different age groups.

Out of 518 children aged between zero and 18, who tested positive for Covid-19, they found that 24.3 per cent were still suffering from persistent symptoms ranging from fatigue to allergic reactions, some five months later, with 12-18 year olds proving particularly vulnerable. “These are children not necessarily admitted to hospital,” says Warner. “These are children with mild and sometimes even asymptomatic infection who have just been picked up because they were contacts of a known case. So it's a considerable burden.”

While teenagers appear to be most susceptible to Long Covid, it can also be seen in even younger children. According to the Office of National Statistics, it occurs in 7.4 per cent of children between two and 11, who have tested positive for the virus.

As a result, while the JCVI is still deliberating over vaccinating 12-18 year olds, other countries are contemplating the prospect of rolling out the jab later this year to even younger children. At the moment, none of the Covid-19 vaccines have been approved for use in under 12s, but both Pfizer and Moderna are currently conducting clinical trials in this age group, with the results anticipated in the next few months.

Guzman-Cottrill says that for many children, vaccination could represent a path back to a more normal life. “This pandemic has been really mentally challenging for children from a mental health perspective,” she says. “It has really taken a toll on their mental health, with the isolation, and the inability to do whatever it is that they love. We have to consider that as well.”

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This article was originally published by WIRED UK