Covid vaccine causes strong immune response in young children, says Pfizer


The Pfizer-BioNTech coronavirus vaccine has been shown to be safe and highly effective in young children aged 5 to 11, the companies said early Monday morning. The news is expected to help allay months of anxiety among parents and teachers about when children and their close contacts could be protected from the coronavirus.

The need is urgent: Children now represent more than one in five new cases, and the highly contagious Delta variant has sent more children to hospitals and intensive care units in recent weeks than at any time of the pandemic.

Pfizer and BioNTech plan to apply to the Food and Drug Administration by the end of the month for permission to use the vaccine in these children. If the regulatory exam goes as well as it does for older children and adults, millions of elementary school students could be vaccinated before Halloween.

Trial results for children under 5 are not expected until the fourth quarter of this year at the earliest, according to Dr Bill Gruber, senior vice president at Pfizer and pediatrician.

Pfizer and BioNTech announced the results in a statement that did not include detailed data from the trial. The results have not yet been peer reviewed or published in a scientific journal.

But the new findings are consistent with those seen in older children and adults, the experts said.

“There are going to be a lot of parents who are going to breathe a big sigh of relief upon hearing this,” said Dr. Kristin Oliver, pediatrician and vaccine expert at Mount Sinai Hospital in New York City. “We were waiting for these children to be protected.

Children have a much lower risk of Covid-19 than adults, even when exposed to the Delta variant. Yet, a small number of infected children develop a life-threatening disease called multisystem inflammatory syndrome in children, or MIS-C. Still others may have symptoms that persist for months.

Nearly 30,000 children were hospitalized for Covid in August; the least immunized states reported the highest rates. At Seattle Children’s Hospital, about half of children admitted for Covid are over 12, according to Dr Danielle Zerr, a pediatric infectious disease expert at the hospital.

“I was appalled that the sickest children in our hospital with Covid-19 or acute MIS-C were children who could have been vaccinated,” Dr Zerr said.

As ideological battles over masking and vaccination warrants unfold in communities, the reopening of schools has fueled the wave. In Mississippi, among states without a mask warrant, nearly 6,000 students have tested positive for the virus in a week, and more than 30,000 students, teachers and staff have had to be quarantined.

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A county in South Carolina – where mask warrants are banned – had to quarantine more than 2,000 students in one day. Distance learning is not an option in many districts, so the safety of some medically vulnerable children in many parts of the country has become subject to the actions of others.

Unvaccinated children, even if they do not get sick themselves, can transmit the virus to family members, teachers and others with whom they interact on a regular basis, including grandparents or those who are vulnerable. serious illness or death.

Wearing a mask and good air circulation can significantly reduce the transmission of the virus. But children are as likely as adults to pass the virus to others, and more likely to do so than adults over 60, according to a recent review of the evidence by the Centers for Disease Control and Prevention.

Pfizer’s trial included 2,268 children aged 5 to 11, two-thirds of whom received two doses of the vaccine three weeks apart; the rest were injected with two doses of saltwater placebo.

Given the paucity of children who become seriously ill, the trial was not large enough to draw meaningful conclusions about the vaccine’s ability to prevent Covid or hospitalization. Instead, the researchers relied on measures of the immune response of young people, assuming that the protective levels of antibodies seen in the elderly would also be protective in young children.

Children who received the vaccine produced a strong immune response, comparable to antibody levels seen in previous trials in participants aged 16 to 25. But children in the 5 to 11 age group got that response with 10 micrograms of the vaccine, a third of the dose given to older children and adults.

At higher doses, researchers observed more side effects in young children, including fever, headache and fatigue, although none were serious, Dr Gruber said. With the 10 microgram dose, “we actually see after the second dose, less fever, less chills than in 16 to 25 year olds. “

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The immune system weakens with age and the side effects also subside. This drop in activity is why most vaccines are given during childhood – and why a much lower dose is often sufficient for children, said Dr Yvonne Maldonado, who led the trial at the ‘Stanford University and chair of the American Academy of Pediatrics. Committee.

“You want to reach the sweet spot, where you are giving the lowest dose that could cause reactions, but also high enough to get you a good, long-lasting antibody response,” she said.

In children under 5, only three micrograms – one tenth of the adult dose – are tested in trials and appear likely to be sufficient, she said.

Full FDA approval of the Pfizer-BioNTech vaccine in August did not include children between the ages of 12 and 15, who still receive the vaccine under emergency use authorization. As they did for teenagers, companies will apply for emergency clearance for children aged 5 to 11.

FDA scientists then need to weigh the benefits of the vaccine against the risk of side effects. In rare cases, the vaccine has caused myocarditis, an inflammation of the heart, in young people.

But a large Israeli study, based on the electronic health records of two million people aged 16 and over, found that Covid is much more likely to cause these heart problems.

In order to detect side effects in young children, the FDA in July asked Pfizer-BioNtech and Moderna to expand their trials to include 3,000 children. But based on the company’s conversations with the FDA, Dr Gruber said he believed the agency would give the vaccine the green light with the data available to date.

Discussions about the risks of the vaccine for children aged 6 months to 5 years are likely to be even more tense than vehement disagreements over immunizing healthy adults or adolescents.

“There are people who don’t really think there is convincing data that children under five need to be vaccinated,” said Dr Maldonado.

Even though most children are spared serious illness from infection, pediatric hospitals and intensive care units are overflowing, she added: “Why wouldn’t you want to prevent an infection that could potentially put your life away. child in intensive care? “


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