Flu, RSV starting to circulate but cases remain lower than last year: CDC

Influenza and other respiratory viruses are starting to circulate but so far remain lower than this time last year, according to the Centers for Disease Control and Prevention.

As of Oct. 7, CDC's FluView weekly report showed that the percent of flu cases were relatively unchanged, rising about 1% compared to the week prior.

In that same timeframe, 1,127 people were hospitalized with influenza, up from 1,050 people the week prior. About 35% of all flu hospitalizations were reported in the southeast of the U.S., which experts say is a typical trend at the start of the flu season.

Most of the flu cases detected were Influenza A and the most common subtype was Influenza A(H1N1), which is the strain of the virus that the flu vaccine usually offers better protection from, according to the CDC.

The percent of all reported respiratory viruses circulating over the past week have been relatively unchanged nationally, but there is regional variability. Region 9 -- made up of Arizona, California, Hawaii, and Nevada -- was the only region that saw an increase.

Still, the numbers in all regions of the U.S. remain below their baseline and outpatient respiratory illness activity is either minimal or low throughout most of the U.S., according to the CDC.

Alaska is the only state that is currently experiencing moderate respiratory illness activity. Influenza typically circulates this time of year and peaks between December and February for most of the U.S., according to the CDC.

Respiratory syncytial virus (RSV) numbers are on the rise and are projected to increase further, according to the CDC's weekly surveillance. RSV typically circulates from October to April, according to the CDC.

How to prepare for this year's cold and flu season

This time last year, the U.S. was bracing for a "tripledemic" amid rising cases of COVID-19, influenza and RSV after the seasons became more unpredictable during the COVID-19 pandemic.

Dr. John Brownstein, chief innovation officer at Boston Children's Hospital and an ABC News contributor, said these early cases are behaving in a more predictable pattern.

"The data is pointing to something a little bit more par for the course. We're seeing the early rise of RSV and flu at a time when you'd expect it," Brownstein said.

Brownstein, however, cautioned that cases of respiratory viruses are expected to increase further and higher levels still have potential to strain health systems and cause severe illnesses, Brownstein said.

"I think there's still concern around the threat of all three respiratory viruses plus, of course, the rest of the seasonal mix [of viral illnesses], wreaking havoc on our health systems," he said.

Experts are hopeful that new and updated immunizations that protect against COVID-19, influenza and RSV will stave off the strain on health care systems.

These viruses may only cause mild illness for many people, but young babies, pregnant women, people who are immunocompromised and the elderly are at highest risk for severe disease.

Everyone 6 months and older is eligible for an updated COVID-19 shot and the annual flu vaccine.

The Department of Health and Human Services told ABC News that, so far, more than 7 million updated COVID-19 shots have been administered. The CDC recommends getting the COVID-19 and flu vaccines by the end of October and encourages both to be given at the same time.

Adults who are 60 years and older can get an RSV vaccine and pregnant women who are in their third trimester can get an RSV shot that provides protection against RSV to their baby for the first 6 months of life.

Babies less than 8 months old who are born to mothers who did not get an RSV vaccine during pregnancy can get a protective shot called nirsevimab that offers about five months of protection against RSV.

Nirsevimab is a one-dose shot made of monoclonal antibodies, which are proteins manufactured in a lab and mimic the antibodies the body naturally creates when fighting an infection. This is different than a vaccine, which activates the immune system.

Brownstein said the pandemic has helped make many health systems better prepared for seasonal spikes in respiratory viruses and is hopeful that people are more motivated to stay up to date on shots that are available for protection and prevention this respiratory virus season.

"Now is really the time to get the protection advanced of the seasons really heating up," Brownstein said.

Dr. Jade A Cobern, M.D., M.P.H, a licensed and practicing physician, is a member of the ABC News Medical Unit.