Public health investigators in Los Angeles County have documented a hepatitis A outbreak inside a skilled nursing facility in which three of the five infected residents had already been vaccinated after being exposed. The findings were published in the CDC journal Emerging Infectious Diseases by the Los Angeles County Department of Public Health.
The conclusion carries a specific practical recommendation. The investigators wrote that "persons in congregate living facilities should receive both the vaccine and immune globulin" after hepatitis A exposure to mitigate further transmission.
That matters for families with a relative in long-term care anywhere in the country. Vaccination alone is the standard response to a hepatitis A exposure for most people, and this outbreak suggests that approach may not be sufficient in a nursing home setting.
The Outbreak Inside a 285-Resident Facility
County health officials were notified of a hepatitis A case in a Los Angeles County skilled nursing facility in January 2025. The facility housed 285 residents across five units, all of whom were over the age of 40.
Five cases were ultimately identified among residents. Three of those five had received the hepatitis A vaccine after their exposure was recognized, which is the recommended postexposure step.
Hepatitis A spreads via the fecal-oral route, making congregate living settings particularly susceptible. Residents who need help with toileting, bathing, or feeding have frequent close contact with staff and shared surfaces, and cognitive impairment can limit independent hand hygiene.
A person with acute hepatitis A is considered infectious 14 days before jaundice appears and up to 7 days after, or 14 days after symptom onset if there is no jaundice, meaning transmission can occur well before anyone recognizes an outbreak is underway.
The Gap Between Vaccine and Immune Globulin
Standing guidance recommends the hepatitis A vaccine for postexposure prophylaxis within 14 days of exposure for people without documented immunity. Immune globulin, which supplies antibodies directly rather than prompting the body to make its own, can be considered for people with particular risk factors for infection or for severe disease.
The distinction is a matter of timing and immune response. A vaccine takes time to generate protection, and that response can be slower and weaker in older adults or people with chronic illness. Immune globulin provides protection immediately.
In a facility where residents are older and frequently have underlying conditions, that lag can leave a window during which exposed residents remain susceptible. The investigators' recommendation is that both be given together in congregate settings rather than relying on the vaccine alone.
This is a single-facility investigation with five cases, and it does not, by itself, change national guidance. It provides direct evidence from a real outbreak that the vaccine-only approach allowed continued transmission in this setting.
A County Already Under a Community-Wide Outbreak
The facility investigation sits within a broader picture. Los Angeles County declared a community-wide hepatitis A outbreak in May 2025 after a sustained rise in cases and elevated virus levels detected in local wastewater.
County health officials reported at that time that 165 hepatitis A cases had been confirmed in the county since 2024, three times the number reported in 2023. Historically, people experiencing homelessness have faced the highest risk because of limited access to handwashing and toilet facilities.
The pattern has shifted. Of the 29 cases confirmed in 2025 as of the declaration, most occurred in people without travel or housing risk factors, which county officials described as corresponding with rising virus concentrations in wastewater. The county maintains updated hepatitis A surveillance data online.
That shift is what connects a nursing home outbreak to ordinary households. When a virus circulates broadly, it reaches staff who commute between the community and the facility and visiting family members before it reaches residents.
Steps for Families and Facilities
Anyone with a relative in long-term care can reasonably ask the facility two questions: whether residents' hepatitis A vaccination status is documented, and what the facility's protocol is if an exposure occurs.
Hepatitis A vaccination is safe and highly effective, and full protection requires two doses given at least six months apart. Previously unvaccinated people can also receive the vaccine soon after an exposure to protect against developing the infection.
Symptoms include fever, weakness, fatigue, nausea, loss of appetite, stomach pain, vomiting, dark urine, pale stools, and jaundice, which is a yellowing of the skin or eyes. Although rare, hepatitis A can cause death in some people, and older adults and people with existing liver disease or other chronic conditions face a higher risk of severe illness.
Handwashing with soap and water remains a core prevention step, particularly before preparing or eating food and after using the bathroom.
Los Angeles County residents with insurance can get vaccinated through health care providers and participating pharmacies, and the county publishes a list of vaccination referral sites. Uninsured or underinsured residents can access vaccination through county public health clinics, and mobile units continue to offer free vaccination to people experiencing homelessness.
Key Questions Answered
What did the investigation find? Five hepatitis A cases occurred among residents of a Los Angeles County skilled nursing facility, and three of the five had been vaccinated after their exposure was identified.
What do the investigators recommend? People in congregate living facilities receive both the hepatitis A vaccine and immune globulin after an exposure, rather than the vaccine alone.
Why would vaccination alone fall short? A vaccine takes time to generate protection, and that response can be slower in older adults or people with chronic illness. Immune globulin supplies antibodies immediately.
Does this change national guidance? Not on its own. This is a single facility investigation involving five cases. It provides real-world evidence supporting the consideration of both interventions in congregate settings.
How does hepatitis A spread? Through the fecal-oral route, usually when a person unknowingly ingests the virus from objects, food, or drinks contaminated with small amounts of stool. People are infectious before symptoms are recognized.
What are the symptoms? Fever, weakness, fatigue, nausea, loss of appetite, stomach pain, vomiting, dark urine, pale stools, and jaundice. Older adults and people with liver disease face a higher risk of severe illness.
How can families reduce risk? Ask the facility about resident vaccination records and exposure protocols; keep household members vaccinated; and maintain hand hygiene with soap and water.
