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Coronavirus transmission rate climbing in L.A. County as economy reopens, old routines return

A cyclist and his passenger fly a Black Lives Matter banner in Venice Beach on Sunday.
(Myung J. Chun / Los Angeles Times)

The coronavirus transmission rate in Los Angeles County is climbing again as the economy reopens.

Officials said the increase in disease transmission largely reflected infections that occurred before the start of demonstrations protesting the death of George Floyd, a black man killed after a white Minneapolis police officer used his knee to pin Floyd to the ground by the neck. Floyd died May 25.

The incubation period for the coronavirus infection can generally last as long as two weeks.

Los Angeles County, the California hotbed of the virus with more than 2,600 deaths, has been gradually reopening its economy. A month ago, L.A. County allowed many stores to open for pickup service. In the last week of May, churches and hair salons were allowed to reopen, and officials allowed the resumption of in-store shopping and in-person dining at restaurants.

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But now, health officials are detecting an uptick in disease transmission. It comes as more businesses are reopening, and more people are returning to old routines. Over the weekend, some shopping centers and public spaces began to see bigger crowds, with only some wearing masks and practicing social distancing.

At its worst, the county’s “effective transmission rate” of the coronavirus was quite high — 3 to 3½ — meaning one infected person on average transmitted the virus to an average of three or 3½ other people. That high point came in March before Gov. Gavin Newsom implemented California’s stay-at-home order.

Eventually, the stay-at-home order worked, and the effective transmission rate fell to 1, and then even a bit below 1. That means that, on average, each infected person was transmitting the virus to fewer than one other person.

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Dr. Christina Ghaly, director of health services for L.A. County, said Friday the effective transmission rate had now risen above 1 and was gaining ground.

“While we don’t know precisely yet how reopening and the recovery activities will affect transmission of COVID-19,” Ghaly said, the transmission rate “does appear now to be greater than one, and slightly uptrending.

The latest maps and charts on the spread of COVID-19 in Los Angeles County, including cases, deaths, closures and restrictions.

“If transmission has indeed increased,” she added, “then the model predicts that we will have a continued increase in hospital patient volume over the next two to four weeks, and we would anticipate beginning to see that change happen over the coming one to two weeks.”

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Hospitalizations for COVID-19 started to tick upward last week after falling to their lowest pandemic level on May 31, when the daily number of those hospitalized for confirmed and suspected coronavirus infection fell to 1,908. That was down from a peak of around 2,600 in early April.

But by Thursday, the number of people hospitalized had risen to 2,048. On Saturday, it was at 1,981.

Ghaly said it was possible the number of intensive care beds could become inadequate in the next two to four weeks based on the number of currently available beds in daily hospital surveys among the county’s public and private hospitals.

“We must all do everything we can to keep the [transmission rate] from continuing to increase,” Ghaly said.

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It's possible LA County could run out of intensive care unit beds if the coronavirus transmission rates continue increasing.
It’s possible L.A. County could run out of intensive care unit beds if the coronavirus transmission rates continue increasing.
(Los Angeles County Department of Health Services)

In the Bay Area, San Mateo County — sandwiched between San Francisco and Silicon Valley — is also seeing an increase in its coronavirus transmission rate.

San Mateo County, which has a population of about 770,000 people and is home to tech giants including Facebook and YouTube, was once a hotbed of coronavirus transmission, with an effective transmission rate of 3 to 4. San Mateo County is just northwest of Santa Clara County, one of the nation’s first centers of the coronavirus pandemic.

But after joining with five other Bay Area counties in implementing the nation’s first regional shelter-in-place order to combat the coronavirus, the effective transmission rate fell to 0.9, meaning that for each person infected, that person on average transmitted it to fewer than one other person.

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“Anything above 1 is not good, and the higher it gets above 1, the worse it is in an exponential manner,” Dr. Scott Morrow, the San Mateo County health officer, said in a statement last week.

Yet Morrow now suspects the transmission rate is up to 1.3. Despite that, he has continued to slowly loosen stay-at-home orders, although not nearly as quickly as L.A. County has. Although in-restaurant dining was allowed to resume in L.A. County two weeks ago, only outdoor dining was allowed to resume last week in San Mateo, Santa Clara, Contra Costa and Marin counties.

San Francisco and Alameda counties have taken even stricter approaches: San Francisco has no plans to allow outdoor dining to reopen until mid-June, and Alameda County hasn’t yet said when it will allow outdoor restaurant dining.

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None of those six core Bay Area counties have allowed hair salons to reopen, and some have not allowed indoor churches to resume operations. Only outdoor religious services are allowed in Santa Clara and Marin counties; San Francisco may not reopen places of worship until next week.

Morrow said his goal was to ease the stay-at-home order as fast as he could “without being reckless.”

“We are certainly in the midst of the biggest disaster of our lives,” Morrow said in his statement. “Pandemics are a spark that can, if not carefully managed, cause a global conflagration. The profound economic shock of this pandemic will be larger than the Great Depression.

“If you have any worry at all about the virus and its effect on you, your family, friends, colleagues, neighbors or others, you should know, it is not completely safe to be out, it is even less safe to attend gatherings of any size,” Morrow said.

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Health officials have always expected the disease transmission rate to increase as the economy reopens. What officials are hoping for is an uptick that the hospital system can handle.

“It’d be one thing to see a slight increase, which we would anticipate from having more people out and about. What we have to avoid is that huge increase that causes a threat to our healthcare system,” Los Angeles County’s director of the Department of Public Health, Dr. Barbara Ferrer, said last week.

Ferrer has said there have been more outbreaks at workplaces, although the overall numbers are still small.

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To keep disease transmission rates from increasing as the economy further reopens, Ghaly reminded residents of these basics:

  • Wash your hands.
  • Wear face coverings when outside or around those who don’t live in your household.
  • Follow quarantine and isolation orders, regardless of whether you are tested or whether you tested negative.

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