Speaking at the White House COVID-19 response team briefing Friday, Centers for Disease Control and Prevention (CDC) Director Dr. Rochelle Walensky said three new reports released by the agency add evidence to the importance of being “up to date” with vaccinations against COVID-19.
They are the first large U.S. studies to look at vaccine protection against omicron and echo previous research indicating vaccines are less effective against the variant than earlier versions of the coronavirus.
But, they also show that boosters significantly improve protection.
“The data here show … the protection provided by vaccines and the importance of being up to date on your COVID-19 vaccination,” Walensky told reporters.
The first study looked at hospitalizations and emergency room and urgent care center visits in 10 states, from August through January.
The researchers found vaccine effectiveness was best after three doses of the mRNA Pfizer or Moderna vaccines in preventing COVID-19-associated emergency department and urgent care visits.
Protection dropped from 94% during the delta wave over the summer to 82% during the omicron wave and protection from just two doses was lower – especially if half a year had passed following the second dose.
The second study examined case and death rates in 25 states from April through Christmas.
During both the delta and omicron waves, people who were boosted had the highest protection against infection.
A third study published by the Journal of the American Medical Association (JAMA), also led by CDC researchers, observed people who tested positive from Dec. 10 to Jan. 1 at more than 4,600 testing sites.
While three shots of the Pfizer and Moderna vaccines were about 67% effective against omicron-related symptomatic disease compared with unvaccinated people, two doses offered no significant protection against the variant.
“Taken together, these data highlight two important points. First, those who remain unvaccinated are at a significantly higher risk for infection and severe COVID-19 disease,” Walensky explained. “Second, protection against infection and hospitalization with the omicron variant is highest for those who are up to date with their vaccination, meaning those who are boosted when they’re eligible.”
“There are still millions of people who are eligible for a booster dose and have not yet received one,” she added. “As we continue to face the omicron variant – representing over 99% of infections in the United States today – I urge all who are eligible to get their booster shot, to get it as soon as possible.”
White House COVID-19 response coordinator Jeff Zients said that 210 million Americans are fully vaccinated, including nearly 75% of adults.
He said those individuals are 16 times less likely to be hospitalized from COVID-19 than those who remain unvaccinated.
“We’re not there yet, but the president’s COVID plan is clearly working. And, we’re confident we’ll continue to make progress to get to where we all want to be,” Zients concluded.
The Associated Press contributed to this report.