Anthony Fauci
Anthony FauciReuters

Top US pandemic advisor Dr. Anthony Fauci on Sunday warned of a “bleak winter” ahead as the Omicron variant of COVID-19 spurs a new wave of infections globally, AFP reports.

"One thing that's very clear... is (Omicron's) extraordinary capability of spreading," Fauci was quoted as having told NBC News. "It is just... raging through to the world."

Fauci cautioned against too much optimism over Omicron's severity, noting that in South Africa, while the hospitalization-to-case ratio is lower than with the Delta variant, this could be due to underlying immunity from widespread previous infections.

"No matter how you look at it," he underscored, "when you have so many, many infections, even if it is less severe, that overcomes this slight to moderate diminution in severity."

"Our hospitals, if things look like they're looking now in the next week or two, are going to be very stressed," particularly in areas of the country with low levels of vaccination, added Fauci.

Fauci urged unvaccinated Americans to get a shot and the vaccinated to get boosters.

While a little more than 70 percent of the US population has had at least one shot, according to the Centers for Disease Control and Prevention, another 50 million eligible people remain unprotected, Fauci said.

"With Omicron... it is going to be a tough few weeks to months as we get deeper into the winter," he added.

Fauci’s comments came as Senator Elizabeth Warren (D-MA) and Senator Cory Booker (D-NJ) announced on Sunday that they tested positive for COVID-19 in breakthrough cases.

In September, Rep. Tim Ryan (D-OH) tested positive for COVID-19 despite being vaccinated. At the time, 10 other lawmakers had also tested positive for COVID-19 despite being vaccinated: Reps. Vern Buchanan (R-FL.), Ralph Norman (R-SC), Sharice Davids (D-KS), Troy Nehls (R-TX), Mike Doyle (D-PA) and Darren Soto (D-FL), as well as Sens. Lindsey Graham (R-SC), Roger Wicker (R-MS), Angus King (I-ME) and John Hickenlooper (D-CO).

Fauci commented in August on the phenomenon of “breakthrough infections”.

“No vaccine is 100% effective, so you can expect breakthrough infections. Most of these infections are going to be asymptomatic or mild,” he explained.

Fauci added that people who have been infected should still get the vaccine in order to add a stronger layer of protection, noting the delta variant is producing more reinfections.