Does the new bivalent COVID booster have different side effects?

(NEXSTAR) – If you go to your local pharmacy or vaccination site, you’ll be getting a new type of COVID-19 shot these days. It’s a bivalent booster shoot, meaning it contains parts of the original COVID-19 variant and the omicron variant that’s grown dominant in 2022.

The new formulation is designed to give you better protection against the type of coronavirus circling now, but does a new type of vaccine mean it will feel different?

“All the side effects from the bivalent booster (in clinical trials) were very similar to what we saw with the regular booster and even going back to the initial vaccination,” said Andrew Pekosz, a virologist with the Johns Hopkins Bloomberg School of Public Health, in a recent media briefing. “Most often it’s redness at the site of inoculation, some soreness, feeling tired for a day or two afterwards — all the same side effects we’re seeing at relatively the same rates with the bivalent booster.”

Other common side effects of the COVID-19 vaccine in adults — whether it’s the updated formula or not — include headaches, fever, chills and nausea, according to the Centers for Disease Control and Prevention.

In kids, the most common side effects are a bit different. For really young children, between 6 months and 3 years old, you’ll often see soreness at the injection site, but also swollen lymph nodes, irritability, sleepiness or loss of appetite.

In children 4 to 17 years old, the side effects are more similar to what adults see. Side effects in this age group are more likely to occur after the second dose, the CDC says.

The CDC says side effects are usually mild and pass within a day or two.

The Food and Drug Administration has authorized the use of two bivalent COVID-19 boosters. The Moderna shot is available for adults, while the Pfizer shot is available for people 12 and older.

It’s hard to say how much better these boosters will protect us from the virus than the last version, because tests of this exact recipe have only just begun in people.

The FDA cleared the new boosters based in large part on human studies of a similarly tweaked vaccine that’s just been recommended by regulators in Europe. Those tweaked shots target an earlier omicron strain, BA.1, that circulated last winter, and studies found they revved up people’s virus-fighting antibodies.

With that earlier omicron version now replaced by BA.4 and BA.5, the FDA ordered an additional tweak to the shots — and tests in mice showed they spark an equally good immune response.

There’s no way to know if antibodies produced by an omicron-matched booster might last longer than a few months. But a booster is also supposed to strengthen immune system memory, adding to protection against serious illness from the ever-mutating virus.

The Associated Press contributed to this report.