The Best Way to Assess Immunity in Children

Jacqueline Almeida cannot wait for next week.

Her friends have seen her look confused when she requests to meet outdoors. It was not easy for her to persuade her sister to get her son vaccinated. Strangers suggested to her via Twitter that she should put her little girl in a mask because it was child abuse.

Yet, the vaccinations of the youngest Americans were delayed after delay. “It was very disappointing, month after month, seeing everything get pushed,”She is 33 years old and lives in Franklin Tenn.

But now there’s some good news: Vaccines should be available in days for her 6-month-old son and 2-year-old daughter. On Wednesday, the Food and Drug Administration received recommendations from scientific advisers that they recommend the Pfizer BioNTech vaccine for children 6 to 4 years old and the Moderna vaccination for children 6 months through 5.

It authorized vaccinations Friday by the agency, and it is expected that the Centers for Disease Control and Prevention (CDCP) will follow its lead Saturday. If all goes according to plan, about 18 million children in this age group will become eligible for immunization against the coronavirus for the first time, the final piece in the nation’s vaccine strategy.

A recent survey found that only about one-fifth of all parents intend to immunize their child right away after experiencing delays due to regulators.

F.D.A. received a written response. Nearly 70 scientists wrote to F.D.A. officials in April stating that the delay could have been avoided. Although their argument may be technical, it has broad implications.

Scientists said that the agency and manufacturers decided to test the vaccines using blood tests. However, regulators might have taken into account other aspects of the immune systems, and it would have been evident that vaccines are capable of preventing serious illnesses, or infection, among young children.

The scientists suggested that vaccine makers should have measured so-called “T cells”, which are capable of killing infected cells. This would help to eliminate the virus from the body. This is what the scientists argued. “would have allowed us to possibly make a different decision about allowing a vaccine to move forward earlier,” said John Wherry, director of the Institute for Immunology at the University of Pennsylvania and one of the letter’s signatories.

“If we don’t measure the T cells, we’re missing a big part of what’s happening,”He concluded. “My gosh, we’re 18 months into this, we can devote a little bit of energy to stuff like that at this point.”

F.D.A. Although the F.D.A. did not respond to Dr. Wherry’s request for comment regarding the letter, he said that scientists from the agency called them about a month before to talk through their ideas.

To determine the effectiveness of vaccines in preventing symptoms from developing, vaccine manufacturers conducted large-scale trials. But in the children’s trials, the investigators looked at blood levels of antibodies following vaccination, comparing them with the levels seen in young adults.

F.D.A. This method is called immunobridging and it was used to approve the Pfizer BioNTech vaccine to children 5-11 years old, as well as adolescents 12-15 years of age. The companies revealed that their vaccine produced low levels of antibodies in two doses for children aged 2 to 4.

The companies decided to assess whether a third dose improved the vaccine’s performance. Infected children from the Omicron trial were discovered over the winter.

The preliminary data about these infections showed that the F.D.A. said it would consider authorizing two doses of the vaccine while the companies continued to test the third — a decision that provoked mixed reactions from parents and experts.

But the number of infections among children grew, and the accruing data did not support the F.D.A.’s decision, prompting the agency to cancel its planned review. As Omicron variants ravaged the country, parents were left confused.

C.D.C. The C.D.C. reported that 75 percent of all children could have contracted the coronavirus between March and April, many of whom were infected during the Omicron flood. Although children had a record number of hospitalizations, they were still much higher than those who received the coronavirus.

Experts said that more information on T-cell immunity may have helped deliver the shots sooner to parents in desperate situations and prevented some hospitalizations.

It is essential to neutralize the virus upon entry. There are many tests that can quickly test for antibodies, but it takes at most a few microliters of blood to assess T cells and at minimum a day just to check a handful of samples.

A vaccine analysis should include T cells. “really up the complexity and cost of the study,”Camille Kotton (infectious disease physician at Massachusetts General Hospital) and scientific adviser to C.D.C.

“It’s never as easy as antibodies, but it definitely would be helpful,”She said.

Not everyone believes that T cells provide immunity. According to Dr. Miles Davenport is an immunologist from the University of New South Wales, Sydney.

“There is no study demonstrating that the level of vaccine-induced T cells is predictive of either the risk of infection or the risk of severe disease,”Dr. Davenport spoke.

Yet, epidemiological data show that despite the decline in antibody levels and rises in infections, hospitalizations, and death rates among vaccinated persons remained very low. According to Dr. Wherry, this suggests that people are protected from serious illness by something else than their antibody levels.

“Mortality is only increasing in the very old population or those who are immunocompromised, where we lacked or had poor T cell responses,”He concluded. “There’s a lot of good circumstantial data out there, but we’re really missing a smoking gun.”

The University of Pennsylvania has a new initiative that may provide some insight. The Immune Health Project is a study that will assess both antibody and T-cell responses after vaccination in immunocompromised patients.

Unanswered concerns about children’s immunity could explain why 40 percent of parents are hesitant to give immunizations. Children aged five through eleven have only received one dose, with the highest demand being for younger children.

Monica Lo (35), is an assistant principal in a Seattle school. She is one of the most hesitant. “Covid vaccination is happening so quick and so fast that we wanted to give it a little bit more time,”She said.

Ms. Lo and her husband were both fully vaccinated. However, their seven-year-old boy, Gian had received only one dose of vaccine before they went on a trip to Hawaii. Data suggesting better immunity might have led them to postpone his second dose. Lo stated.

They also have a 2-year old daughter and Ms. Lo is currently pregnant with their 3rd child. She will arrive in July. But they don’t plan to vaccinate their daughter just yet, Ms. Lo stated: “We will not be first in line.”

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