Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), and the leading infectious disease expert, Dr. Anthony Fauci, testify before the Senate Health, Education, Labor, and Pensions Committee on Capitol Hill in Washington, DC, July 2021, 2021.

J. Scott Applewhite | Swimming pool | Reuters

CDC director Dr. Rochelle Walensky said Thursday that Americans may not need annual Covid-19 booster vaccinations, suggesting a third vaccination could sufficiently strengthen the long-term protection of Pfizer or Moderna vaccines.

Walensky’s remarks come a day after she and other senior U.S. health officials said they plan to offer booster programs to all eligible Americans eight months after their second vaccination. The effectiveness of mRNA vaccines degrades over time, especially for those at high risk of dangerous coronavirus complications or those who were immunized early in the vaccine launch, Walensky and several of the country’s leading medical officials said on Wednesday an explanation.

“This virus was humiliating, so I don’t want to say never, but we don’t necessarily assume you will need this annually,” Walensky said in an interview on CBS’s This Morning on Thursday. “It looks like you’re getting a really robust response after that third dose, and so we’ll continue to pursue the science on both the vaccine and virus sides.”

In a separate interview on NBC’s “TODAY” Thursday, she cited other vaccines, such as hepatitis B, that require two basic vaccinations followed by a booster vaccination. She said scientists believe the Covid vaccine could offer similar long-term protection after three doses.

“We know we need a boost now, and we will continue to pursue the science, but I don’t think it goes without saying that we do this continuously,” Walensky told TODAY.

Health officials are still investigating whether recipients of the Johnson & Johnson vaccine will need an additional dose. If formal approval is given by the Food and Drug Administration and recommended by a CDC vaccine advisory panel, the distribution of booster doses for Moderna and Pfizer recipients will begin on September 20.

“We plan for late September and have had discussions with the FDA and (the CDC’s Advisory Committee on Immunization Practices) and think this is a very reasonable schedule,” she told CBS.

Regardless, former FDA commissioner Dr. Scott Gottlieb that health officials will try to administer the boosters to stave off a winter surge in Covid cases.

“The first two [doses] were administered so close together that they really qualify as two prime numbers, ”said Gottlieb in an interview on Thursday in the CNBC’s“ Squawk Box ”.

The highly transmittable Delta variant that raged in the United States this summer now accounts for 98% of new Covid cases in the United States, Walensky told CBS. According to the CDC, 51% of Americans nationwide were fully vaccinated as of Wednesday.