Dangerous weeks ahead in L.A. County as coronavirus suddenly surges. Here is why

A few weeks ago, there was cautious optimism that this winter would not see a significant COVID-19 surge.

But in Los Angeles County, that outlook is in jeopardy. Case counts are climbing rapidly, sending increasing numbers of Angelenos to the hospital and raising the possibility of a renewed public indoor mask mandate that could arrive shortly after the new year.

But why is the nation’s most populous county contending with such a significant spike?

Some factors that may be at work include a shorter incubation period for the latest Omicron strain, meaning there would be a shorter period between when someone is exposed to the virus and when they become infected.

“People came back from Thanksgiving and pretty quickly were testing positive,” county Public Health Director Barbara Ferrer said. At her agency, “we had more people who tested positive right after Thanksgiving than we’ve ever had before,” with transmission occurring during holiday gatherings, rather than at work.

“A shorter incubation period could be contributing to a more rapid increase in cases earlier on in December than we saw the past two years,” she said.

BQ.1 and BQ.1.1 are now the dominant versions of the coronavirus circulating nationwide. Their parent strain, BA.5, was said to have an incubation period of three to five days.

For the week ending Tuesday, L.A. County reported an average of 3,829 new coronavirus cases a day — double the rate from Thanksgiving. On a per capita basis, that’s a rate of 265 cases a week for every 100,000 residents. A rate of 100 or more is considered high.

A year ago, the county was recording 112 new cases a week for every 100,000 residents.

“We’re having this increase starting a little bit earlier,” Ferrer said in an interview with The Times.

Public health officials have long marked Thanksgiving and the wider winter holiday season as a potential starting point for a surge. With so many gatherings scheduled over just a few weeks, and many held indoors due to colder weather, conditions are ripe for a coronavirus rebound — as has happened each of the past two years.

The multigenerational nature of such events also plays a role, as older residents are more at risk of developing severe COVID-19 illness.

Ferrer said she’s concerned that many people have stopped worrying about COVID-19. But if there’s any time to start paying attention, it’s now, she said.

“We are seeing a rapid acceleration again,” Ferrer said. “This is the time to put that mask back on.”

Officials also stress that it’s important to get updated COVID-19 vaccine boosters — which were introduced in September — and are urging more doctors to prescribe antiviral drugs like Paxlovid for eligible patients.

“That also would accomplish one of our biggest goals,” Ferrer said, which is reducing how many people are falling severely ill.

And she urged people to not be dismissive about the fact that it’s older people who are most likely to die from COVID-19. Preventive measures such as wearing a mask can reduce illness, she said.

Holiday events can result in coronavirus outbreaks, but taking certain precautions can reduce the risk. Strategies include taking events outside and wearing a mask when not actively eating and drinking, Ferrer said.

At smaller gatherings in homes with friends and family, hosts may consider having everyone take a rapid coronavirus test before the event, Ferrer said. It will help identify those who are most likely to be infectious, even if they’re asymptomatic.

But a testing-only strategy alone is not perfect, because there are situations in which some people are contagious but not yet testing positive on a rapid coronavirus test.

And of course, officials say residents should stay home if they’re sick.

“This is about real people, real lives, real families and real communities across the state, so doing your small part helps the state certainly. But more importantly, it helps you and your family have the safest holiday season that you can,” California Health and Human Services Secretary Dr. Mark Ghaly said.