As concerns over omicron variant grow, experts say don't wait to get a booster

Amid a renewed surge of coronavirus infections and hospitalizations across the country, and concerns surrounding the newly discovered omicron variant, health experts are again pleading with Americans to get vaccinated, and if fully vaccinated and eligible, to get a booster.

"Do not wait. Go get your booster if it's time for you to do so," President Joe Biden said earlier this week during an address at the White House. "If you are not vaccinated, now is the time to go get vaccinated and to bring your children to go get vaccinated."

Although it is still unclear whether the omicron variant is more transmissible, if it causes more serious illness or impacts vaccine effectiveness, the World Health Organization said on Monday that the overall global risk is assessed as "very high," due to the variant's mutations.

In light of the global whirlwind of concern, vaccine makers are currently testing the shots' effectiveness, and announced plans this week to tweak vaccines in order to address the new variant, if deemed necessary, leaving some Americans wondering whether they should rush to get a shot now or wait to see if the vaccines are readjusted.

"I would strongly suggest you get boosted now, and not wait for the next iteration of it, which we might not even need," Dr. Anthony Fauci, chief medical adviser to the White House, told ABC News' George Stephanopoulos Monday on "Good Morning America," adding that he would "not at all" recommend waiting. "We'll find out reasonably soon whether higher levels of antibody against the original vaccine that we've used, whether or not that can spill over in protection against this."

'We may not have time to wait'

Many experts have echoed Fauci's sentiment, urging Americans to get the shots as soon as possible, given all of the uncertainties about omicron.

"We don't have all the answers we want as of yet. In a few weeks, we will know a lot more," Dr. Colleen Kelley, an associate professor of medicine in the division of infectious diseases at Emory University School of Medicine, told ABC News.

With prior variants, she said, as long as the levels of antibody were high enough, a variant-specific booster did not seem necessary.

"We hope that this will also be the case with omicron and that high levels of antibodies will maintain some level of protection, but don't know for sure yet. So, my recommendation is to get boosted now," Kelley said.

If omicron proves to be as highly transmissible as delta, "we may not have time to wait for the omicron-specific booster to protect people," Kelley added.

On Wednesday, scientists in California confirmed the first known case of omicron in the U.S., and experts say the variant is likely already circulating within other communities.

"People should not wait for the vaccine to be tweaked to adapt to the new variant as it would be many months until that new vaccine is released. They should get a primary vaccine now or a booster, and then when the updated vaccines are available we may well need additional doses of the vaccine then," Dr. Camille Kotton, clinical director in the Infectious Diseases Division at Massachusetts General Hospital, told ABC News.

According to the White House, the process of introducing a variant-specific vaccine would take approximately three months, and would include necessary sign off from the Centers for Disease Control and Prevention and the Food and Drug Administration.

"The companies currently estimate that it would take a few months to prototype and manufacture a modified vaccine or booster and that does include, to your question, the time for FDA and CDC to do their evaluation, so the estimate of a few months is all inclusive," White House COVID coordinator Jeff Zients said Tuesday during a press briefing.

In light of the omicron's potential threat, CDC Director Rochelle Walensky announced that the agency would be strengthening its recommendation for all adults to get a booster shot six months after their Pfizer or Moderna vaccines or two months after the Johnson & Johnson shot.

"The recent emergence of the Omicron variant further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19," Walensky wrote in a statement on Monday.

Additionally, on Tuesday, Pfizer announced it has officially asked the FDA to authorize COVID-19 booster shots for 16- and 17-year-olds.

Vaccines will likely still provide 'good' protection against variants

Several experts stressed that even if the vaccines were found to be less effective against the omicron variant, the current vaccines still present "good" protection.

"Even if omicron has some immune evasive properties, boosters are likely to still provide good protection based on some mutational experiments researchers have performed with viruses containing the same mutations as omicron," Dr. Angela Rasmussen, a virologist at the University of Saskatchewan, told ABC News.

Other experts urge caution, given how little scientists know about omicron.

Although "it is prudent to get your boosters, we have a lot to learn about omicron," said Dr. Jennifer Lighter, a hospital epidemiologist for NYU Langone Health. If it is indeed more contagious, she said, it could lead to more breakthrough cases, and therefore, boosters would increase antibody levels and convey an extra layer of protection from breakthroughs.

However, Lighter said she does not believe that it would make much difference to get the booster now, or in a few weeks, stressing the fact that the immune response after vaccination is quite broad.

"Your immune response knows that there will be mutations. And the immune response is actually much wider, and not only specific for what someone was vaccinated against," Lighter told ABC News.

Hence, with vaccination, there is protection against severe disease, and if omicron is indeed more contagious, breakthrough infections will likely "predominantly be mild in most people."

Data has consistently shown that vaccinated individuals have fared much better than unvaccinated.

Unvaccinated individuals had a 5.8 times greater risk of testing positive for COVID-19 and a 14 times greater risk of dying from it, as compared to vaccinated individuals, according to federal data compiled in September 2021.

At this time, approximately 100 million Americans remain completely unvaccinated, about 80 million of whom are currently over the age of 5, and thus are eligible to get the shot.

"We still have less than 60% of the United States population fully vaccinated. So I think it's important to first stress that the unvaccinated people will eventually get COVID. It will come to them sooner or later," warned Lighter.

"We should definitely take this opportunity to protect ourselves, thus protecting our loved ones, our communities, our country and the world," added Kotton.

ABC News' Cheyenne Haslett contributed to this report.