American health officials say most people should get the updated COVID-19 vaccine this year.

Last week, the U.S. Centers for Disease Control and Prevention (CDC) approved the updated COVID-19 shots from Pfizer and its partner BioNTech as well as from Moderna. A third vaccine from Novavax remains under study.

Who should get the updated vaccines?

U.S. health officials approved the shots for adults and children as young as six months old. They said starting at age five, most people can get a single shot even if they have never had a COVID-19 shot. Younger children might need more shots depending on their history of COVID-19 infections and vaccinations.

CDC Director Mandy Cohen said last month that she expects the COVID shots to be given yearly like the flu vaccines. However, not all doctors agree that everyone needs them every year.

Dr. William Schaffner, an infectious diseases specialist at Vanderbilt University, is an advisor to the CDC. He said, "If you're six months of age or older, you should get a flu vaccine. Sounds good to me for COVID also."

Another CDC advisor is Dr. Paul Offit, a University of Pennsylvania infectious disease expert. He said he believes the shots should be given yearly to high-risk groups. Studies have not shown the updated shots protect against disease in lower-risk populations, Offit said.

In Britain, the British government's vaccine committee said only adults 65 and older and people at risk will be offered the shot as they are the most likely to benefit.

Will the shots be effective?

Unlike last year's shot which targeted both the original virus and the Omicron variant, the updated shot takes aim at an Omicron sub-variant named XBB.1.5. The drug companies added that early testing has shown that the updated shots work against the latest sub-variant BA.2.86.

Officials from the World Health Organization (WHO) recently said BA.2.86 has already been identified in several countries, including the United States, Switzerland, South Africa, Israel, Denmark and Britain.

The severity of the COVID-19 pandemic has decreased. But WHO Director-General Tedros Adhanom Ghebreyesus said the new COVID-19 variants show that the virus remains a health threat around the world.

The CDC said last month that only 42 percent of people said in a study that they would or probably would get the new vaccine. Yet only about 20 percent of American adults got an updated shot, called a booster, when it was offered a year ago.

Doctors hope enough people will get vaccinated to help avoid another "tripledemic" like last year. At that time, U.S. hospitals said they had to deal with an early flu season, a rise in respiratory syncytial virus known as RSV, and another sudden increase in coronavirus cases.

This year, hospitals in the U.S. reported a small increase in COVID-19 patients over the summer. But the number was much smaller than the year before. Officials said earlier vaccinations or infections have helped prevent severe disease and death. But most Americans have not had a vaccination in about a year.

The CDC says that people can get a yearly flu shot and the updated COVID shot at the same time. The agency says there is no difference in effectiveness or side effects.

I'm Mario Ritter, Jr.

Hai Do adapted this report for VOA Learning English from Associated Press and Reuters sources.

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original –adj. happening or existing first

variant –v. something that is a little different from members of a group of similar things