Pfizer Shot Is Far Less Effective in 5- to 11-Year-Olds Than in Older Kids, New Data Show


The coronavirus vaccine produced by Pfizer BioNTech is said to be far less effective in preventing infection in children aged 5 to 11 years than in older adolescents and adults. Large new dataset Collected by New York State Health Authority — Findings that have a profound impact on these children and their parents.

The Pfizer vaccine is the only Covid shot approved for that age group in the United States. It still prevents serious illness in children, but there is little protection against infection, even within a month after complete immunization. Data collected during the Omicron surge suggests.

The sharp decline in vaccine performance in young children may be due to the fact that they receive one-third of the dose given to older children and adults, the researchers who reviewed the data said. Said federal officials.

Survey results, Posted online on MondayFollowing the results of clinical trials, the vaccine shows that it did not work in children aged 2-4 years.

Experts were worried that the news would further discourage parents hesitating from immunizing their children. Other studies have also shown that the vaccine was not strongly protective against infection by adult Omicron mutants.

“It’s a shame, but not surprising, given that this is a vaccine developed for a previous variant,” said Eli, Deputy Director of Science at the New York State Department of Health, who led the study.・ Rosenberg states. “It looks very painful to see this rapid decline, but it’s all against Omicron.”

Still, he and other public health experts said he would recommend shots to children given protection against the severe illnesses shown even in the new dataset.

“We need to emphasize donuts, not holes,” said Dr. Catherine M. Edwards, a pediatric vaccine expert at Vanderbilt University.

In their study, Dr. Rosenberg and his colleagues were newly fully vaccinated 852,384 years aged 12 to 17 years, who were omicron high from December 13, 2021 to January 31, 2022. We analyzed data from children and 365,502 children aged 5 to 11 years swell.

The effectiveness of the vaccine for hospitalization decreased from 85 percent to 73 percent in older children. In younger children, efficacy dropped from 100% to 48%. However, few children are hospitalized, so these estimates are inconsistent.

The number of protection from infection is more reliable. Vaccine efficacy against infections in older children decreased from 66% to 51%. But for younger children, it plummeted from 68 percent to just 12 percent.

Numbers vary dramatically between the ages of 11 and 12. Vaccine efficacy against infections during the week up to January 30 was 67% at age 12 years, compared to only 11% in children 11 years old.

“The difference between the two age groups is striking,” said Florian Kramer, an immunoscientist at Mount Sinai School of Medicine.

The biological difference between the two ages is likely to be negligible, he said, while a 12-year-old child was vaccinated with 30 micrograms, while an 11-year-old child was vaccinated with only 10 micrograms. rice field.

“This is very interesting because it almost suggests that it is the dose that makes the difference,” he added. “The question is how to fix it.”

At least there was 851 deaths associated with Covid-19 Children under the age of 17 and about 7,000 Pediatric multisystem inflammatory syndromeA rare but serious condition associated with Covid. More children were hospitalized during the Omicron surge than at any other time in the pandemic.

The findings underscore the need to collect more information about the best dose, number, and timing of shots given to a child, Dr. Rosenberg said. They also emphasize vaccines as just one means of protection from viruses, along with masks and social distance.

Dr. Rosenberg’s study was posted just days after the US Centers for Disease Control and Prevention was announced. New recommendations It will allow the majority of Americans to stop wearing masks, including at school.

The new data also raises important questions about the Biden administration’s strategy for vaccination of children. Only about 1 in 4 children between the ages of 5 and 11 receive it Two doses of vaccine.. (CDC has not yet recommended booster immunization for this age group.)

The vaccine has not yet been approved for children under the age of five. A Food and Drug Administration scientific adviser was scheduled to meet on February 15 to evaluate two doses of the vaccine for the youngest child while the three doses were still being tested. However, the meeting was postponed after Pfizer submitted additional data. This suggests that the two doses did not provide strong protection against the Omicron variant of the virus.

Dr. Rosenberg published the findings in early February and briefed top CDC executives, including agency director Dr. Rochelle P. Warrensky. FDA leaders learned the data at about the same time. Some federal scientists called for the release of data prior to the FDA expert meeting scheduled for February 15, and considered it highly relevant to discussions on dosing for children under the age of five. I did.

Data is generally Report from the UK The effectiveness of the vaccine for symptomatic treatment in adolescents aged 12 to 17 years has been shown to decrease to 23% after 2 months. The CDC has compiled its own data on the effectiveness of the vaccine in infants and plans to release at least some of it as early as this week, according to people familiar with the authorities’ plans.

Israeli researchers have also evaluated the performance of vaccines in young children since the country made the vaccine available in November.

“We continue to investigate and evaluate the actual data from the vaccine,” said Amy Rose, a Pfizer spokeswoman, in answering questions about the new data.

Dr. Philip Krause, who recently retired from the FDA as a senior vaccine regulator, said assumptions about specific antibody levels that predict vaccine efficacy should be reassessed in the light of new results.

“It certainly undermines the debate about requiring people to get that lower dose,” he said.

As more evidence becomes available, it is not uncommon for specialists to revisit the administration and intervals of pediatric vaccines. However, in this case, giving the child a high dose to initiate an immune response may not be an option. Because there are data suggesting that it may cause too much fever, unwelcome and potentially dangerous side effects in young children.

Deepta Bhattacharya, an immunologist at the University of Arizona, states that there are other options that may improve the immunity of young children.

Pfizer and BioNTech are testing a third dose in children under the age of 5 and children between the ages of 5-11. This is because, as in adults, additional shots can significantly improve immunity. The results of these trials are expected within a few weeks. Studies in adults suggest that three doses of the vaccine are more protective against the Omicron variant than two doses.

Based on a study suggesting that increasing the gap between doses may improve protection, Dr. Bhattacharya said he and his wife were 8 in 8 weeks instead of the currently recommended 3 weeks. He said he was spaced between the two doses for 10 children. CDC last week Encouraged people over 12 years oldBoys and men, especially 12-39 years old, wait 8 weeks between the first and second shots.

Another option could be a version of the vaccine designed to block the Omicron variant, or a mixture of several variants. Pfizer-BioNTech, Moderna, Johnson and Johnson are all testing Omicron-specific versions of the vaccine.

The following variants can be very different from Omicron, just as Omicron is the Delta variant. However, training the body to recognize multiple versions offers a better chance to prevent infection by new forms of the virus. “Determining when and how best to renew these vaccines is an important conversation in the future,” said Dr. Batacharya.

New vaccines that use a different approach than currently approved in the United States may also be more effective for children. The protein-based vaccine produced by Novavax is under review by the FDA, and pharmaceutical companies Sanofi and GSK said this month that they will soon submit the vaccine for evaluation.

Many parents prevent their children from spreading the virus to vulnerable relatives, send them to school, or have a long Covid that is a long-standing, poorly understood symptom that can occur even after a mild infection. I would like to vaccinate my child to avoid the possibility. Experts acknowledged that the low effectiveness of the vaccine against infection does not alleviate these concerns.

Still, vaccines “provide more protection than we think,” said Jessica Andreessen, a vaccine data expert at the Fred Hutchinson Cancer Research Center in Seattle.

“They may also prevent your child who brought Covid home from shedding the virus as much as if they were not vaccinated. They also have it in a shorter amount of time. There may be, “she said.

The virus stays here and the risk of children with serious consequences increases with age. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia and an adviser to the FDA, said it was a good idea to inoculate children early.

“When I talk to my parents about this vaccine, I insist on them that your child will grow up,” he said. “They will need to be protected from this virus for years.”

Sharon La Franiere and Isabel Kershner contributed to the report.

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