For the first time this fall, there will be three different vaccines against the biggest respiratory virus threats: a new Covid booster, the yearly flu shot and two RSV vaccines for older adults.
On Tuesday, state health officials urged eligible Americans to get the vaccines ahead of what many believe could be an intense winter respiratory season, especially after several years of unpredictable viral activity.
"We are very, very concerned about the upcoming pan-respiratory season," Dr. Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials, said during a media briefing Wednesday. ASTHO is a group that represents public health agencies nationwide.
What's unclear, however, is when Americans should get the shots, particularly the updated Covid vaccine that will target the XBB virus variant.
The group couldn't say for sure when to get that shot, as it hasn't been approved.
RSV, or respiratory syncytial virus, and flu usually spread between Halloween and the end of spring. Covid cases and hospitalizations are already ticking up — well before a typical respiratory virus season.
Covid-related hospitalizations were up 12.5% over the past two weeks, according to the Centers for Disease Control and Prevention. A new Covid variant called EG.5, a version of the once dominant XBB variant, is spreading in the U.S. It's still unknown whether EG.5 will be responsible for a Covid surge in the coming months.
"The problem with Covid right now is that we don't know when the Covid season is," said Dr. Todd Rice, director of the medical intensive care unit at Vanderbilt University Medical Center in Nashville. Rice was not involved with the ASTHO briefing.
Different from previous years, Americans should expect just one Covid booster through the season, said Dr. Anne Zink, ASTHO president and chief medical officer for the Alaska Department of Health. "We really want to make this easy and simple," she said.
The Covid vaccine should also work against EG.5, said Dr. Joseph Kanter, state health officer for the Louisiana Department of Health.
"The expectation is that the updated monovalent boosters that will become available in the coming one to two months will retain good activity" against that omicron subvariant, Kanter, who also participated in the ASTHO briefing, said.
Dr. Sharon Nachman, chief of the division of pediatric infectious diseases at Stony Brook Children's Hospital in New York City is more cautious about the upcoming Covid vaccine.
"We can't know how effective the vaccine will be until it rolls out," Nachman said.
Evidence so far, Rice said, suggests that Covid vaccines are most effective for about three months. "Then it wanes pretty heavily," he said. Rice is part of a large group of researchers looking at the effectiveness of both Covid and flu vaccines, called "Investigating Respiratory Viruses in the Acutely Ill" (IVY) Network.
When will fall vaccines be available?
Different from previous years, Americans should expect just one Covid shot this fall, Zink said. "We really want to make this easy and simple," she said.
Right now, Pfizer's updated Covid vaccine is in production and could be authorized by the Food and Drug Administration by the end of the month. At that point, the Centers for Disease Control and Prevention is expected to sign off on the shot, with a recommendation on who should get it.
Other vaccines and treatments this fall
Flu shots will also be recommended this fall, as usual. Zink said that she and her colleagues are seeing "a lot of cases of influenza" in the Southern Hemisphere right now, which could be an indication of what's to come in our part of the world.
Last year, flu season peaked earlier than usual, then quickly fell.
While it seems the flu shots are a good match for flu strains beginning to circulate, "there could be curveballs," Zink said, "and we don't know how those curveballs are going to come at us."
The RSV vaccine for adults ages 65 and older, along with a new monoclonal antibody injection for babies and a third vaccine up for approval, have the potential to drastically reduce cases of the virus that typically hits infants and older adults hardest, experts say.
According to the CDC, RSV hospitalizes up to 160,000 people 65 and older each year, leading to up to 10,000 deaths.
Experts say there is early evidence that combining the RSV shot with the Covid and flu shots may lessen the effectiveness of all three.
Still, health experts urge people to get the shots when they're available and not worry too much about timing.