4 News Now Q&A: How will Pfizer’s COVID vaccine be tweaked for younger kids?

Your Questions Answered

Q: How will Pfizer’s COVID vaccine be tweaked for younger kids? 

A: Experts say the main difference between adult and child vaccines will be dosage.

Knowing children have developing immune systems, Pfizer tested various doses in its trials of children ages 5 to 11. As it turns out, kids have a strong immune response to even lower doses.

Doctors say dosage is typically determined by factors like weight, age and how a particular vaccine moves throughout the body. A vaccine dose that is too high could cause severe short-term side effects; a dose that is too low may be ineffective.

Researchers say that means children younger than 12 will most likely be getting a 10-microgram dose of the vaccine, instead of the 30-microgram given to adults.

For the youngest children — children younger than 5 — doctors are testing a 3-microgram dose of the vaccine.

Scientists conducting these trials report this lower dose keeps side effects to a minimum. They say the most common symptoms they found were headache and fatigue. Only around 10 to 11 percent of children experienced fevers and chills. Like adults, those side effects lasted a day or two.

“This dose seems to provide great antibody responses,” Stanford Pediatric Infectious Disease Specialist Yvonne Maldonado said. “Some people have even talked about whether there should be efforts to look at the lower doses in adults too.”

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FURTHER READING: Pfizer says COVID-19 vaccine works in kids ages 5 to 11