Many experts advise prompt vaccination for children under 5 years old to prevent new strains, while others say that health authorities need to be careful when data on vaccines for this age are incomplete.
The US Food and Drug Administration (FDA) said on February 2 that it will review the Pfizer vaccine to make a decision on whether to approve it for children 6 months to 4 years old. The review meeting took place before clinical trials showed that the company’s standard three-dose regimen was effective. This is an unprecedented move.
Unlike the adult trial, experts were not able to assess effectiveness by comparing infection rates between the vaccine and placebo groups. Instead, the FDA put antibody threshold in people aged 16 to 25 years as vaccine criteria should be met. This research method, called “immunocombination,” is commonly used as the basis for licensing vaccines in adolescents.
In results Pfizer announced in December 2021, with a two-dose course, children aged two to four years old did not produce as many antibodies as teenagers, meaning the test did not meet FDA standards. The experts decided to inject a third dose. According to the unnamed federal official, the effectiveness of the vaccine in children 2-4 years old is 57%. Data from the third dose trial is expected to be released in the coming weeks.
The FDA’s push for a pharmaceutical company to submit an application for approval of a drug or vaccine has also never happened before. The rapidly evolving pandemic forces federal health officials to make important decisions with limited data. Their top priority is to vaccinate young children now, before a new, more dangerous strain emerges.
The US drug agency’s acceptance to consider incomplete data as a basis for vaccine evaluation has some experts worried. Dr. Gregory Poland, founder and director of the Vaccine Research Group at the Mayo Clinic and editor-in-chief of the journal Vaccine, said: “We’ve never done this before, which is something that concerns me. I don’t. satisfied with the lack of data”.
Dr. Poland and some experts say the third dose of vaccine can not always help boost immunity in young children. As the Omicron strain increases, many scientists feel the FDA should wait for the full test results, which are expected to be released in the coming weeks.
Approving vaccines before complete data are available could undermine public confidence in the agency’s processes, making parents hesitant about getting their children vaccinated. Experts ask the question “What happens when the third dose doesn’t work, and millions of parents have given their children two doses?”.
Although it is generally difficult for young children to become seriously ill after nCoV infection, during the Omicron outbreak, the number of pediatric patients hospitalized was unusually high. Some studies show that hospitalized children often have underlying medical conditions, such as diabetes, chronic lung disease or heart disease, that are more likely to lead to more severe symptoms.
According to some experts, instead of licensing the vaccine for all 18 million children 6 months to 4 years old in the US, the FDA should consider recommending vaccinations for high-risk children.
However, the series of infections in children under the age of 5 during the Omicron outbreak has many parents anxious for a vaccine.
“On the one hand, parents are eager to protect their children, on the other hand, there is a very skeptical attitude. The whole process needs to be done very transparently and carefully,” said Natalie Dean, birth statistician. study at Emory University in Atlanta, said.
FDA scientific advisors will meet on February 15 to review current data. The Centers for Disease Control and Prevention (CDC) may order two doses immediately afterward.
The administration of President Joe Biden promised to respect the decision of the medical advisers. “You need to understand that the FDA won’t skip any aspect of the review process. They know they’re the gold standard that the public can trust,” said Dr. Vivek Murthy, MD, a general practitioner. .
According to two sources familiar with the US health agency, promoting immunization in children and booster vaccination in adults is a step forward in the future, in case new strains appear.
“We are concerned that as more and more children experience persistent Covid-19 syndrome, some of them develop autoimmune disease or type 1 diabetes following infection with nCoV,” said Stephanie Cacomo, an FDA spokeswoman.
Dr. Diego Hijano, pediatric infectious disease specialist at the St. Jude, the inspector in the Pfizer trial, said childhood immunizations could start as early as April. That means they could go through the summer without getting three doses of the vaccine.
“Certainly, in the summer, some disturbing strain will spread,” he said.
For other scientists, the new strain is not a compelling reason to vaccinate children under five too early. According to Dr. Poland, the balance of benefits – harms when vaccinating children at this time is very different from that of adults at the beginning of the pandemic.
“At this point, we are not making decisions in the context of the epidemic is still chaotic and unclear. As an immunization expert, I need to consider more,” he said.
Pre-approval of a two-dose regimen may encourage some parents to have their children vaccinated to protect their children in school. Others will wait until data on the third dose is complete.
Thuc Linh (Follow NY Times)