Children ages 6 months to 6 years will soon be getting a slightly different COVID-19 vaccine for their third dose.
As with adults and older kids, their third shot will be a so-called bivalent vaccine, targeting both the original virus and a variant that was widely circulating for much of this year.
The Food and Drug Administration signed off on the vaccine change Thursday morning and the Centers for Disease Control and Prevention followed suit Friday.
The change applies to third doses of both the Pfizer-BioNTech vaccine, called Comirnaty, and Moderna's vaccine, named Spikevax, though there are slight differences in age and dose between the two.
The new shots should be available almost immediately, according to both companies and Walgreens, which is making appointments for next week.
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Why get young kids an updated shot?
Government health officials and many pediatricians are encouraging people of all ages to get an updated COVID-19 shot, which will hopefully provide more protection against the currently circulating variants.
Data has shown that at least three doses are needed to protect against the omicron variant because of its differences from the original virus, which is what the vaccines were designed to fight against.
The original vaccine was extremely effective at preventing both severe disease and mild COVID-19. The evolution into omicron robbed the vaccine of its ability to prevent most infections, though the shots still protect against severe disease.
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The vaccines also become less protective over time, with older people and those who are immune compromised at greatest risk.
The bivalent shot boosts antibodies against omicron variants BA.4 and BA.5, which had dominated in the U.S. from the late spring into the early fall. Now, BA.5 accounts for just about 14% of COVID-19 cases, with newer omicron variants BQ.1 and BQ.1.1 accounting for over 60%.
Although the antiviral Paxlovid is believed to remain effective against all the variants, there are no longer any monoclonal antibodies that can reduce disease severity once someone is infected.
Generally, children have not been as affected by COVID-19 as older adults, though they can still become severely ill, requiring hospitalization. Pediatricians and other health professionals have said that the benefits of the COVID-19 vaccines outweigh their risks in all age groups, including the youngest children.
Side effects of a third or booster dose are similar to those from initial doses for all ages.
With more people spending time indoors as temperatures drop, and holiday gatherings bringing generations of families together, officials have encouraged people to get the added protection of another shot.
"As this virus has changed, and immunity from previous COVID-19 vaccination wanes, the more people who keep up to date on COVID-19 vaccinations, the more benefit there will be for individuals, families and public health by helping prevent severe illnesses, hospitalizations and deaths," FDA Commissioner Dr. Robert Califf said in a prepared statement.
What's changed for the Pfizer-BioNTech vaccine?
The Pfizer-BioNTech vaccine is meant to be given in three doses to children ages 6 months through 4 years old.
That means the third dose is technically not considered a booster but part of the primary series. The change will only affect the third dose, not the first two, so if a child started getting vaccinated now, their first two doses would be with the original vaccine and the third with this newer bivalent shot.
All three doses are 3 micrograms, one-tenth of the dose given to adults and teens.
Young children who already received three doses of the Pfizer-BioNTech vaccine are not eligible for a booster dose of the bivalent vaccine. The original vaccine series is expected to continue to protect these children against severe disease, the FDA said.
Data on whether it makes sense to give a fourth, bivalent dose for these children are expected in January.
Doses of the bivalent vaccine for young children are ready to be shipped almost immediately and should be available within a few days, Pfizer said in a news release.
Children are not immune to either COVID-19 or long COVID, in which symptoms linger for months or longer, said Dr. Aida Habtezion, Pfizer's chief medical officer.
"We don't know who are the children who are susceptible to develop these diseases," Habtezion said. "At the moment, we need to protect all children."
What's changed for the Moderna vaccine?
The Moderna vaccine for the youngest children, up to age 6, is delivered as two primary doses, with a third dose expected to be needed for longer term protection.
The change means the first booster dose would target both the original virus and a more recent variant.
Children 6 months through 5 years of age who received the original Moderna COVID-19 vaccine are now eligible to receive a single booster of the updated bivalent vaccine at least two months after completing the initial doses.
Moderna's vaccine for the youngest children is delivered in a 10 microgram dose.
Contact Karen Weintraub at firstname.lastname@example.org.
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This article originally appeared on USA TODAY: CDC, FDA authorize COVID bivalent vaccine for kids