COVID-19 cases and test positivity rise in California as summer approaches

COVID-19 activity is increasing in California, with the Centers for Disease Control and Prevention noting a rise in the share of emergency-room visits linked to the virus across several western and southern states. The California Department of Public Health said test positivity climbed to 3.4% for the week ending July 18, up from 1.15% a month earlier, and wastewater monitoring shows higher viral concentrations.

State health spokesperson Grant Boyken said the upward trend is evident in both testing data and wastewater samples. UC San Francisco infectious-diseases specialist Dr. Peter Chin-Hong noted that many residents have not been infected for an extended period, making a seasonal increase plausible. Kaiser Permanente’s regional infectious-diseases chief Dr. Elizabeth Hudson reported a modest rise in outpatient cases over the past two weeks.

Los Angeles County’s positivity rate rose to 4.28% for the week ending July 11, up from 1.52% the previous week, while Orange County saw a rise to 3% from 1.3% a month earlier. Northern California cities, including San Francisco, reported higher wastewater detections, and Santa Clara County labeled levels in San José and Palo Alto as “high.”

Hospitalization rates remain “very low,” but officials expect them to increase as the summer progresses. State health officials continue to advise vaccination for all individuals aged six months and older, emphasizing booster doses for higher-risk groups such as older adults, pregnant people, and the immunocompromised.

The World Health Organization reported low global COVID activity in late June, though some regions experienced increases. Experts caution that, despite lower mortality compared with earlier pandemic years, COVID-19 can still cause severe illness and long-term complications, particularly among vulnerable populations.