RIVERSIDE, Calif. (KABC) -- Riverside and San Bernardino counties have now reached the "high" transmission level.
The number of hospitalizations hit nearly 300 in San Bernardino County Wednesday, which marks the highest level since February. In Riverside County, that number was closer to 240.
Amid the rise in hospitalizations, Dr. Adrain Cotton with Loma Linda University Health says that likely more than two-thirds of those cases are patients who are already in the hospital who then test positive.
"Usually what we see with variations of viruses as they mutate, two things usually happen. One, they usually become a little more contagious so they are more likely to spread a little faster through communities. But the more important part is they are usually become a little less dangerous, a little less lethal," Cotton said.
Cotton credits vaccinations, booster shots and available therapies, but he cautions that people who are immune compromised still need to take precautions in public.
Orange County reached the "high" community transmission level last week. Health officials said the surge in cases is due to the highly transmissible omicron subvariants.
Leaders in Riverside, San Bernardino and Orange counties all say they have no plans to implement new mask mandates unless they are ordered to do so by the state.
L.A County is also in the "high" COVID transmission level, and has been since July 14.
If the county stays at the high category for two weeks straight, officials would bring back rules requiring the wearing of masks during most indoor public activities. At earliest that would be July 29.
The surge in cases across the Southland may be the result of Fourth of July gatherings. But unlike past surges, this summer's may be more of a bump in the road.
"If there is a bright side, our deaths have not followed with an increase as it had previously," said Jose Arballo with Riverside County Public Health.