Wave of RSV sweeping across U.S.; shots urged

U.S. Centers for Disease Control and Prevention.

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RSV is the leading cause of U.S. infant hospitalization and presents particular risk for the youngest babies.

(FRANCINE ORR Los Angeles Times)

RSV can cause pneumonia, as well as a severe inflammation of the lungs' small airways, known as bronchiolitis, the California Department of Public Health said.

“The issue with kids is that their airways are so small that when it causes inflammation in the airways, it’s just very hard to breathe,” said Dr. Peter Chin-Hong, a UC San Francisco infectious diseases expert. “And that’s why they get into trouble.”

Nationally, RSV kills up to 300 children under age 5 annually, and can send up to 80,000 to the hospital. Among seniors age 65 and older, the virus can cause up to 10,000 deaths in a typical year and as many as 160,000 hospitalizations, according to the CDC.

“Until recently ... we couldn't test for RSV,” Chin-Hong said. “So it has been kind of an invisible epidemic.”

In general, RSV is the first to emerge during the fall-and-winter virus season, followed by flu then COVID, Chin-Hong said.

Before immunizations became available, about 2% to 3% of young infants were hospitalized for RSV annually, according to the CDC. Most children who are hospitalized for acute respiratory disease caused by RSV were previously healthy, according to a study published by the journal Pediatrics.

They may require oxygen or intravenous fluid or even be put on a ventilator to help them breathe, according to the CDC.

Unlike the flu and COVID-19, there are no antiviral drugs to treat RSV once infection sets in.

For now, the combined activity of respiratory illness from RSV, flu and COVID-19 is considered “very low” in California, state health officials said.