California maintains a rigorous public health commitment to monitoring the human immunodeficiency virus (HIV) epidemic within its large and diverse population. The state’s surveillance program tracks the scale of the virus and the rate of new infections. Understanding this data is important for directing prevention programs and allocating state and federal resources. The resulting data informs targeted strategies for treatment and prevention, ensuring public health efforts are focused where the need is greatest.
Current Prevalence and Scope
As of 2023, the total number of people living with a diagnosed HIV infection in California exceeded 143,000 individuals. This figure represents the overall prevalence of the virus. The corresponding prevalence rate for the state was 355.0 per 100,000 residents.
This total has steadily increased, rising from approximately 137,777 individuals in 2019. The increase is largely attributed to improved medical treatments allowing people with HIV to live longer, healthier lives. A public health objective involves ensuring that persons living with diagnosed HIV (PLWDH) achieve viral suppression, meaning the virus is reduced to undetectable levels. In 2023, 66.5% of PLWDH in California had achieved this status, an outcome that prevents onward transmission.
Recent Trends in New Diagnoses
While prevalence tracks the total burden of the disease, incidence focuses on the rate of new HIV diagnoses occurring each year, which measures ongoing transmission. The annual number of new HIV diagnoses in California increased between 2019 and 2023. Specifically, the number of new cases rose by 6.0%, from 4,669 in 2019 to 4,948 in 2023.
This upward trend resulted in the rate of new diagnoses increasing from 11.7 to 12.3 per 100,000 population during the same period. Tracking new diagnoses is important for prevention efforts because it highlights current transmission chains and allows public health officials to intervene with targeted testing and medication programs.
Geographic and Demographic Distribution
The HIV epidemic is not distributed evenly across California, showing distinct concentrations in major metropolitan areas and among specific demographic groups. The federal “Ending the HIV Epidemic” initiative identifies eight priority counties in the state, including Los Angeles, San Francisco, San Diego, and Alameda, which account for the highest proportion of cases. These counties are the focus of intensified prevention and treatment efforts.
Analysis of new diagnoses reveals disparities across different populations. The most common transmission category remains male-to-male sexual contact (MMSC), which accounted for 60% of new diagnoses and 71% of all people living with HIV in 2022.
While Latine individuals constituted the largest percentage of new diagnoses in 2023 at 57%, Black/African American individuals face the most disproportionate impact. The rate of new HIV diagnoses among Black/African Americans was 30.9 per 100,000 population in 2023, compared to 6.8 per 100,000 among Whites. Injection drug use (IDU) as a transmission category is a challenge for care retention, as it is associated with the lowest rates of viral suppression. The highest percentages of all living cases are found among cisgender men and those in the 45-to-64-year age range.
Monitoring and Reporting Methods
The California Department of Public Health (CDPH) Office of AIDS (OA) is the central agency responsible for the state’s comprehensive HIV surveillance system. This system relies on mandatory, confidential reporting requirements established by state law. Health care providers and clinical laboratories must report all confirmed HIV diagnoses to their local health officer.
The reporting also extends to all HIV-related laboratory results, such as CD4 cell counts and viral load measurements, which monitor treatment efficacy and disease progression. Since April 2006, this process has been name-based, providing the state with data to track individuals through the continuum of care. The data is securely managed through electronic systems like CalREDIE, ensuring confidentiality while enabling accurate public health tracking and resource allocation.