Health officials are urging gay and bisexual men to get vaccinated for hepatitis A.
The virus has already killed 20 people and sickened over 600 since an outbreak began last month among San Diego's homeless population, reports the Los Angeles Times, prompting California to delare a state of emergency.
And men who have sex with men, in addition to homeless people, first responders, and members of law enforcement, are considered an at-risk group.
"This could be a huge public health crisis," Janice Helm, an L.A. county supervisor, told the Los Angeles Times. She urged members of all of these groups to get vaccines. A police officer in the Los Angeles Police Department was recently infected.
Hepatitis A has already impacted Los Angeles County's LGBT community this year — 15 gay and bi men have reportedly contracted the virus this year in a separate outbreak.
The virus is highly contagious, and can be transmitted through contaminated food, sex, and fecal matter. Each year, gay and bi men account for around 10 percent of new hepatitis A cases, reports the Centers for Disease Control.
L.A. County's health department is offering free vaccines at its clinics.