SANTA ANA, Calif. (CNS) — The number of COVID-positive patients in Orange County hospitals has increased by four people to 138, and the number of those patients in intensive care rose by five to 17, according to the latest state data out Sunday.

While Orange County's COVID-19 infection rates have continued a steady upward swing in recent weeks, hospitalizations have remained relatively stable.

The county has 28.5% of its ICU beds available, according to the Orange County Health Care Agency — well above the 20% level when officials get concerned.

"Hospital numbers moved slightly in the right direction and certainly the ICU level doesn't concern me," Andrew Noymer, an epidemiologist and UC Irvine professor of population health and disease prevention, told City News Service on Friday.

"Frankly, I'd rather see hospitalizations below 100 than above it, but I've already said and I'm not changing my mind that we have to see 200 before I'm really concerned."

Some of those hospital cases may be what officials call "incidental," as they are patients who were admitted to be treated for another malady and tested positive. It was unclear what the ratio is.

The county's testing positivity rate increased from 6.9% on Monday to 7.6% as of Thursday. The rate went from 3.2% to 3.8% in the health equity quartile, which measures the communities hardest hit by the pandemic.

The 7.6% rate "is too high, but everyone knows COVID is happening. It's not a secret," Noymer said. "So it's punching through boosted people. ... Breakthroughs are happening and it's sort of more of the same."

Noymer said he is most concerned about a rising tide next winter.

"My real big fear is next winter, also because people are over getting boosted again and again and winter will be another six months away of waned immunity," he said.

The daily case rate per 100,000 people in Orange County increased from 23.7 to 25.6 Thursday on a seven-day average with seven-day lag, and from 17.7 to 19.2 for the adjusted rate with a seven-day average and seven-day lag.

The county logged 3,091 more infections Tuesday through Thursday, raising the cumulative case count to 575,086. The overall death toll increased to 7,045.

Of those hospitalized, 83.3% are unvaccinated, and 86.5% of ICU patients are not inoculated, according to the OCHCA.

All of the fatalities logged Friday occurred last month. May's death toll rose to 21, while April's death toll stands at 30, March's is 86, February's is 330, January's is 554, and December's is 115.

The case rate per 100,000 people for fully vaccinated residents who have received a vaccine booster increased from 27.7 on May 21 to 30.8 on May 28, the latest data available show. The case rate for residents fully vaccinated with no booster went from 17.2 to 18.3, and the case rate for residents not fully vaccinated went from 25.2 to 27.