Dr. Anthony Fauci said this week that COVID-19 hospitalizations are rising for unvaccinated Americans and also recommended that a booster shot for those who are vaccinated.

“What we’re starting to see now is an uptick in hospitalizations among people who’ve been vaccinated but not boosted,” Dr. Fauci, the director of the National Institute for Allergy and Infectious Disease, said in an interview.

“It’s a significant proportion, but not the majority by any means,” Fauci added.

Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention also noted on Wednesday at a White House COVID briefing, that hospitalizations are rising for the elderly, who were among the first to be eligible for vaccinations. Walensky recommended that the booster shot can be beneficial for protection as well.

“Although the highest risk are those people who are unvaccinated, we are seeing an increase in emergency department visits among adults 65 and older, which are now again higher than they are for younger age groups,” Walensky said.

“The rate of disease is markedly lower for those who received their booster shot, demonstrating our boosters are working,” Walensky added.

Recommendations for booster shots come as winter and traveling for the holidays comes closer, which some are afraid may cause cases to drastically rise again.

There is an expectation that the Food and Drug Administration will authorize booster doses of Pfizer and BioNTech vaccines for all adults 18 and older, prior to a U.S. advisory panel meeting scheduled for Friday.

Booster shots are still being questioned by scientists as a necessity, and are not yet officially U.S. policy.