Why children reduce their COVID vaccine dose

Nicknames became widespread months after Pfizer announced plans to apply the COVID-19 vaccine to children. LilPfizer, Pfizer-Mini, Pfizer Jr. (Sorry, BioNTech. Everyone tends to forget you). Others offer cheeky play with Comirnaty, the official title of the shot’s tongue: Comirnito, Baby Comirnaty, or my personal favorite, ComirNatty Light..

These monicas nod to the actual size of the dose itself, as well as the small humans whose shots are designed. If Pfizer gets the expected approval from CDC director Rochelle Walensky this week, children aged 5-11 will receive 10 micrograms of RNA per Pfizer shot. This is one-third of the 30 microgram recipe given to people over the age of 12. Going further, children under the age of four get only 3 micrograms, one-tenth of what their parents get, while another set of votes, approvals, and recommendations is pending.

At first, it sounds like pretty weird COVID math. A 5-year-old body does not look like an 11-year-old body. It may seem strange that they take the same dose. And surely, when someone turns twelve, nothing physiologically obvious happens. “You don’t wake up one day and have a different immune system,” Kathryn Edwards, a pediatrician and vaccinologist at Vanderbilt University Medical Center, told me.But for some reason, the difference between the days triple Inoculation amount for children. Considering other brands like Moderna, the photo looks even darker. The calculation method is different: 100 micrograms of RNA for adults; 50 micrograms for ages 6-11. 25 micrograms for children under 5 years old. What do you get scientifically?

Thankfully there teeth The logic of how pediatric shots are designed and administered. Children are not just miniaturized adults, vaccines are not sandwiches. Dividing a shot into quarters or halves is not enough to properly pair the two. The goal is to make the shot more than just kids-size, But kids-Friendly,in short Tinker around Many factors, Includes dosing, but how vaccine recipes are stabilized and stored, how much liquid is injected into the arm, who administers the vaccine, and the vials they use. Even the color is included.

Read: 5 Big Questions About COVID Vaccines for Kids

First, consider that children’s vaccines are not given like most drugs.Many drugs will not work without them Reach a certain concentration in the blood, Therefore it should be administered At the size of a child (think Tylenol). That is the Goldilocks principle. Sufficient medication is needed for treatment, but not at risk of toxicity. Vaccines have similar sweet spots, but not too few or too many, but they are calculated differently. Here, researchers pay less attention to weight. And we are paying more attention to how easily the body can marshall antipathogen defenses. Many aspects of a child’s immune system are more intense than adults. Their bodies are packed with more natural punches. Edwards told me that 10-year-olds of different sizes should be expected to respond to the vaccine in a “basically functionally same” way. (Obesity, notably, Have Shown in Dull response to some vaccinesHowever, it is unclear if or how it will affect COVID shots. )

“Children’s immune system probably peaks around the age of 15,” Archana Chatterjee, a pediatric infectious disease specialist at Rosalind Franklin University, told me.For example, according to data submitted by Pfizer to the FDA, children aged 12 to 15 years who have just been vaccinated More antibodies After a full size shot, than an adult. (((Similar phenomenon was Observed with HPV vaccine, This is for adolescents. After that, the defensive moxy declines and becomes dull and forgetful over time. The less natural defense the immune system can provide, the more vaccines are needed.

This broad pattern means that it is safer and more practical to give a trimmed version of an adult dose to smaller children. This is a strategy already adopted for shots used to block other viral diseases such as: influenza And hepatitis A and hepatitis B. (The tendency can also work in reverse: the flu vaccine is given at taller than dose For people over the age of 65-an extra shock to the weakening of the immune system. ) Conservative dosing is also a good way to minimize the bad consequences that tend to be so common that the immune system is elicited, Chatterjee told me.

Pfizer is in the early stages, including children aged 6 months to 11 years, who were given four different doses of the company’s vaccine (3 micrograms, 10 micrograms, 20 micrograms, and 30 micrograms (adult dose)). I tested the idea in a clinical trial. Researchers monitored side effects and immune responses and selected two minimum doses for further study.Especially the dose of 10 micrograms aged 5 to 11 seemed to tickle the blood Antibody level Pfizer said it was “comparable” to what the company saw in teens and young adults. Recent press release..And the final company figures submitted to the FDA are pediatric doses 90.7% valid so Prevention of symptomatic cases Infection of delta coronavirus mutants with COVID-19 in this age group several months after inoculation, including during the summer.Low-dose side effects were also standard in older children and young adults — arm pain, malaise, headaches — but many of them More gentle and more tolerable.. (These symptoms get a little worse with higher vaccine doses and are an impediment to children’s scale-up.)

Bill Gruber, senior vice president of clinical research and development for vaccines at Pfizer, told the FDA’s advisory board last week that he “believes that he has optimized the immune response and minimized it” at 10 micrograms. rice field. Grace Lee, chairman of the Commission for Advising CDC Vaccine Recommendations, told me that balancing was very important. “It makes sense if you can get the same level of protection at low doses.”

Read: Vaccine data for children under 5 years old is coming by the end of the year‘

One asterisk of Pfizer’s comfortable safety data so far is Rare but serious side effects Detected in other age groups vaccinated with mRNA: myocarditis and pericarditis, inflammation of the heart and surrounding tissues. These appear to appear more often in boys and young men. Pfizer’s trial between the ages of 5 and 11 Did not detect caseHowever, it only enrolls thousands of children and is too few to reliably pick up the signal. Low doses are also expected to reduce the risk of these events. If there is a link between myocarditis and testosterone, As some researchers hypothesizedChildren who are not yet adolescents may be less vulnerable. But almost a year after the vaccine was deployed, the urgency of protecting infants who have not yet had a full vaccination green light “has to make some decisions under uncertainty … and , I’m willing to change my mind if I have more data. ” Will appear, “Lee told me.

This does not mean that the exact age group Pfizer has chosen represents a strict scientific boundary... Kit Longley, senior manager of Pfizer’s Science Media Relations, asked the company how he chose the age limit for vaccination, saying: With the FDA. ” of course.

Moderna’s chief brand officer, Kate Cronin, was a bit confusing. She pointed out puberty as one of the considerations the company used to block the age groups over 12 and under 12 (hormones can gently weaken immune function). What schedule is used for other vaccines? Children tend to go to school around the age of 5 or 6 when they are given a lot of vaccine boosters. And up to the age of two, it may be a reasonable range to distinguish the “infant period” when the newborn’s immune system is finding its foothold. (Actually there is Little point Giving a specific shot 6 months before birth: The baby is full of antibodies inherited from the mother and needs time to strengthen its immune defenses. )

Some protracted squeeze is probably why many parents are wondering what to do with their wobbling children on the 12th. This is an age surge that instantly triples the dose of vaccine. But experts told me that parents shouldn’t worry about age accuracy. “Your immune system doesn’t know exactly when your birthday is,” she said. Children on this cliff will respond enthusiastically to both doses. (CDC draft Provisional clinical consideration Regarding Pfizer’s pediatric vaccine posted today, it states that children should be vaccinated based on their “age on the day of vaccination.” This means that a child who turns 12 between two doses of Pfizer can receive 10 micrograms and then 30 micrograms. The dose is “not considered an error”. Pfizer had several participants who turned 12 during their child’s trial and received the same injections each time. )

The bigger consideration is soon Vaccination can raise the child’s defensive shield. Even after the second shot, it will take some time for protection to begin. “I don’t know when COVID will enter your life or your child’s life,” said Sallie Permar, a pediatrician and vaccine expert at Weill Cornell Medicine. Told me last week.. Edwards, a Vanderbilt vaccinologist, agrees that waiting is gambling. She said that five of her seven grandchildren belong to a group between the ages of five and eleven. “All five will be vaccinated on the first day.”