LA County declares hepatitis A outbreak

Public health officials say cases of hepatitis A have more than tripled in L.A. County since 2023, prompting the county to declare an outbreak.

Since the start of 2024,165 cases have been identified; there have been 29 cases to date this year. Typically, the county sees 30 to 50 cases a year.

Hepatitis A is a highly contagious disease that affects the liver. It’s most often spread when people eat food or drink water that’s been contaminated by the virus, and contamination usually happens because people did not properly wash their hands after using the bathroom.

Most people recover from hepatitis A without lasting liver damage, but in some cases it can lead to liver failure or be deadly.

Doctors say vaccination is the best defense. Public health officials are urging people to go to their doctor, pharmacy or a county public health clinic to get vaccinated and prevent further spread.

Tracking the outbreak

The L.A. County Department of Public Health identified the uptick in cases using a new tool: wastewater analysis.

Since 2023, they’ve analyzed samples from the Hyperion and A.K. Warren wastewater treatment plants, which receive sewage from about 75% of L.A. County residents.

Public health officials initially thought the outbreak that began in 2024 was getting better, but this year's numbers are elevated again.

In just the first three months of 2025, 29 cases of hepatitis A have been identified, compared to just 14 cases during the same time period in 2024. At least seven people have died during this outbreak, officials said at a news conference Monday.

“Because we are beginning to see this increase again, and because most of our cases do not have risk factors, we are letting everyone know that any L.A. resident who hasn't been previously vaccinated for hepatitis A should go ahead and get vaccinated,” said Dr. Sharon Balter, director of the county public health department’s division of communicable disease control and prevention.

Why the outbreak?

It’s not entirely clear why the outbreak is happening, officials said. But there are some leading theories.

Typically, hepatitis A outbreaks occur among people who are unhoused, are consistent drug users, or have recently traveled to a country where hepatitis A is present. However, the data doesn’t reflect those populations this time, and the numbers are far higher than typical, which is why health officials are stressing this is an outbreak.

Balter said a likely reason for the outbreak now is because the universal hepatitis A vaccine rolled out here in L.A. County in 1999, so many adults today never got vaccinated.

“ This does mean that there's a large cohort of adults who may not have been vaccinated because they were born afterwards,” Balter said. “We didn't do a catch-up vaccine, and then some people may not have received the vaccine when they were younger.”

What’s next? 

Officials are stressing: Get vaccinated.

Two shots taken six months apart should have you set for hepatitis A protection for life, officials said.

“ Any L.A. resident who hasn't been previously vaccinated for hepatitis A should go ahead and get vaccinated,” Balter said. “It's a very safe, very effective vaccine. You can get it through your provider or you can just go to a pharmacy.”

Uninsured or underinsured residents can visit the county’s public health clinics to receive a vaccine.

Balter added that if you aren't sure whether you've received the vaccine, it’s safe to get it again.