San Diego County is facing a simultaneous public health challenge that has become tragically familiar to West Coast cities: rising hepatitis A and mpox case counts among residents experiencing homelessness, concentrated in downtown encampments where sanitation is inadequate, vaccine access is limited, and the conditions for rapid disease spread are persistently present. The San Diego County Public Health Department has confirmed ongoing hepatitis A surveillance activity among the county's unhoused population, while the hepmag.com national hepatitis tracker documents San Diego health officials as urging vaccinations amid rising hepatitis A and mpox cases as of late 2025, with concerns continuing into 2026.

San Diego County has more than 10,000 unhoused residents, one of the largest homeless populations in the United States relative to its overall size. The 2017 hepatitis A outbreak — which killed 20 people and infected more than 500 — originated in San Diego's homeless encampments and spread to the general population through a combination of poor sanitation and food handler exposure. Health authorities never want to repeat that outbreak, which drew national attention and became a case study in how preventable deaths occur when outbreak warning signs are ignored.

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Hepatitis A in Encampments: The Outbreak Pattern That Haunts San Diego Officials

Hepatitis A spreads through fecal-oral transmission — contaminated food, water, or surfaces — conditions that are endemic in homeless encampments with limited access to handwashing facilities, portable toilets, and clean water. The virus can survive on surfaces for weeks and can spread from a single infected person to dozens of others who share food or use the same facilities. The incubation period of 15 to 50 days means that by the time cases become visible, the transmission chain has typically been running for weeks.

San Diego's challenge is compounded by a concurrent mpox concern. The city's large LGBTQ+ community — particularly concentrated in the Hillcrest and North Park neighborhoods — experienced significant mpox clade II transmission during the 2022 outbreak. As clade I mpox cases arrive on the West Coast, San Diego public health officials are monitoring closely and expanding JYNNEOS vaccination access. California's CDPH notes that anyone who has had close physical or sexual contact with a person with mpox, or who has recently traveled to affected regions, should seek vaccination.

What San Diego's Health Department Is Doing — and What Residents Can Do

San Diego County has deployed mobile vaccination clinics to downtown encampments, partnering with organizations including Father Joe's Villages and the Regional Task Force on Homelessness to administer both hepatitis A vaccines and JYNNEOS mpox vaccines to unhoused individuals. Any person who has not been vaccinated against hepatitis A — including housed residents who spend time near encampments, work in food service, or travel to countries with hepatitis A outbreaks — should verify their vaccination status with their healthcare provider.

The San Diego County hepatitis A vaccine resource page provides information on vaccination sites. For residents near Gaslamp Quarter, East Village, and the downtown core who have had recent contact with individuals in encampments: a two-dose hepatitis A vaccine series is 94–100% protective and widely available at no cost at county health clinics. San Diego's 2017 outbreak demonstrated conclusively that waiting until deaths occur before mobilizing vaccination is both morally and fiscally unacceptable. The question in 2026 is whether officials will act at the scale required before — not after — the next preventable outbreak takes lives.