Single-dose vaccine is the third authorised in the US and is 85 percent protective against severe illness.
Dr Anthony Fauci, the US’s top infectious disease official, is encouraging Americans to accept any of the three available COVID-19 vaccines, including the newly approved Johnson & Johnson shot.
The US government authorised Johnson & Johnson’s single-dose COVID-19 vaccine on Saturday, making it the third to be available in the country following ones from Pfizer/BioNTech and Moderna.
Both of those vaccines require two doses and need to be shipped frozen. The J&J vaccine can be shipped and stored at normal refrigerator temperatures.
“All three of them are really quite good, and people should take the one that’s most available to them. If you go to a place and you have J&J, and that’s the one that’s available now, I would take it,” Fauci said on Sunday on NBC’s Meet the Press programme.
The J&J vaccine was given final approval for widespread use on Sunday.
Both the Pfizer and Moderna vaccines showed higher efficacy rates in trials that used two doses versus J&J’s single-shot vaccine.
However, Fauci and other experts say direct comparison is difficult because the trials had different goals and J&J’s was conducted while more contagious new variants of the virus were circulating.
Fauci said studies are under way to determine their effectiveness and safety for children under 18, who are less likely to get sick from the virus.
Elementary-school students could get doses towards the end of the year or the beginning of next year, while high-school students could get it in the fall, Fauci said.
The new vaccine gives the US government another option as it tries to immunise as many Americans as quickly as possible.
About 14 percent of Americans received at least one dose so far, according to government data.
President Joe Biden has said there should be enough supply to vaccinate all Americans by the end of July.
COVID-19 has killed more than half a million people in the US, and states are clamouring for more vaccines to stem cases, hospitalisations and deaths.
Daily infections have declined dramatically since their January peak, and some states have begun to loosen restrictions on public gatherings.
However, Fauci warned that caseloads could rise again if officials move too quickly.
“It’s really too premature right now to be pulling back too much,” he said.