The U.S. Centers for Disease Control and Prevention (CDC) says it has evidence COVID-19 vaccines work against the omicron variant.
Citing three studies, the CDC said the vaccines appear to work particularly well for those who received booster shots. The U.S. studies are the first to examine the effectiveness of the vaccines on the omicron variant.
One study said it found that vaccines were effective in lowering hospitalizations and urgent care center visits after three doses of Pfizer or Moderna.
The study said three shots were 90% effective in preventing hospitalizations during both the delta and omicron surges.
It said protection against urgent care center visits fell from 94% during the delta wave to 82% during the omicron wave.
Another study focused on deaths and found those who had received boosters had the highest protection against infection from both delta and omicron.
The third study looked at those who had been vaccinated and then tested positive with COVID-19. It said three shots of Pfizer or Moderna were 67% effective against symptomatic cases of omicron compared with unvaccinated people.
Two of the studies found the protection offered by the vaccines wanes to varying degrees as time goes on.
"If you are eligible for a booster and you haven't gotten it, you are not up to date and you need to get your booster," CDC Director Dr. Rochelle Walensky said during a White House briefing Friday.
Also during the briefing, Walensky said the average number of omicron cases was down nationally by about 5%, mostly in areas where it began to surge. She said there were about 744,600 cases per day on average in the past seven days.
She warned that some parts of the country could still see an increase in infections.
"In some parts of the country we are seeing the number of daily cases caused by the omicron variant beginning to decline," she said. "The surge in cases started at different times in different regions and [we] may continue to see high case counts in some areas of the country in the days and weeks ahead."
Some information in this report came from The Associated Press.