The triple threat - or "tripledemic" - of influenza (flu), COVID-19 and respiratory syncytial virus (RSV) have many of the same symptoms in common.
Dr. Darrin Privett, who works for Henry Mayo's Santa Clarita Emergency Medical Group, told Eyewitness News he's treating all patients.
"We have had patients who have tested positive for COVID, but it's primarily influenza or RSV, or a lot of other respiratory viruses sprinkled with COVID," he said.
On Friday, L.A. County logged 3,756 new COVID infections, along with 17 more virus-related deaths.
The county's "high" COVID-19 level move came when the county's average rate of new infections rose to 258 per 100,000 people -- well above the threshold of 200 per 100,000.
County Public Health Director Barbara Ferrer said the move will not trigger a return to any lockdowns or business closures that were imposed at the height of the pandemic. But she warned that being in the "high'' category means the virus is rampant in the area, and the odds of being exposed are growing.
"We are not asking people to curtail their activities, to avoid activities or to shut down any activities,'' she said. "We're letting people know that the risk is higher with elevated transmission, and because this is having an impact on our health care system and our vulnerable residents, it's time to layer in sensible protections.''
Brian Whelin, the owner of Foothill Gym in Monrovia, told ABC7 most of his customers have been COVID-19 free despite not wearing masks.
"So we do know that not using a masks was very safe in general terms you are moving about you are not confined in a small space there's air flow windows open," he said.
Ferrer noted that with the current infection rate, there's an 80% to 90% chance that at least one person is infected with the virus at an event or gathering of 200 people.
Ferrer has said the county will re-impose an indoor mask mandate if it remains in the "high'' category and if the county's virus-related hospitalization numbers reach two thresholds:
- If the rate of daily hospital admissions tops 10 per 100,000 residents
- If the percent of staffed hospital beds occupied by COVID patients tops 10%
The county has already surpassed the first threshold, with the rate of daily hospital admissions already at 14.8 per 100,000 residents as of Thursday. The percent of hospital beds occupied by COVID patients was 6.9% as of Thursday, still below the 10% threshold.
Ferrer said the health department's initial projections showed that the hospital bed percentage would reach 10% by Dec. 20, but she said admission numbers appear to have leveled off in the past three days, meaning it may be longer before the figure reaches 10% -- if at all.
"We're not sure that we'll get there,'' she said.
"We're going to be hopeful that in fact we're starting to see perhaps some leveling in the need for people to be treated at hospitals,'' Ferrer told reporters.
Mask wearing, however, continues to be "strongly recommended'' by the county at indoor public settings. But Ferrer said that even absent a mandate, residents should start wearing them.
"We all need to wear our masks now,'' she said, again citing multiple studies showing their effectiveness in preventing spread. "We've reached a threshold ... where there's just too much transmission, and it's creating a lot of risk.''
Masks are still required indoors at health-care and congregate-care facilities, for anyone exposed to the virus in the past 10 days, and at businesses where they are required by the owner.
City News Service, Inc. contributed to this report.