‘BA.5 is destined to be our dominant virus’

BA.5, along with its close relative BA.4, is a subvariant of the omicron variant. But, according to Wachter, BA.5 has “enough alteration in the spike protein” that it’s even better than earlier versions at getting around so-called neutralizing antibodies, proteins that circulate in your body, grabbing onto and disabling virus particles before they can get into your cells. That means people exposed to the latest version of COVID-19 are more likely to catch it, even if they’ve been boosted or recently infected.

“The die is now cast: BA.5 is destined to be our dominant virus,” Wachter tweeted this weekend.

That may be why everyone you know seems to have COVID right now. In fact, according to data on laboratory-confirmed reinfections from the California Department of Public Health, three times as many people were reinfected with COVID-19 per week in the first three weeks of June as were per week between March and May. It’s not all bad news, though: If you’ve been infected or vaccinated previously, your immune system likely still remembers how to fight off the virus, protecting you from serious illness and death.

According to the California Department of Public Health, which tracks reinfections, BA.4 and BA.5 “are 10% more transmissible than BA.2 and can partially evade immunity from vaccination or previous infection (including prior BA.1 infection). There is no evidence of increased disease severity due to these sublineages at this time.”

That’s in keeping with data out of the UK and South Africa, which have both been hit hard by the new subvariants. In the UK, confirmed infections increased by 30% in the last week of June, largely caused by BA.4 and BA.5, but there was little change in hospitalizations. In South Africa, BA.4 and BA.5 cases spiked in May, without major increases in hospitalizations or deaths.

According to the Centers for Disease Control and Prevention, which tracks variants by region across the country, recent data shows BA.5 is becoming the dominant variant across the country. In region 9, which includes California, the BA.5 sublineage made up 51.9% of confirmed omicron cases sequences in the region, up from 40.5% the week before.

In response to the new data, an FDA panel last week recommended that vaccine manufacturers add genes that encode the BA.4/BA.5 spike protein to the next round of booster clinical trials.

In San Francisco, official case counts are on the rise. The seven-day average is about 430 cases per day, as of June 26. Three months ago, the average was about 100 cases a day. Wachter said on Twitter that because of home testing, the actual case number is much higher.

Wachter said that while deaths have not increased in the US amid the BA.5 surge, hospitalizations are on the rise. San Francisco has seen an uptick, going from 21 total COVID-19 patients in acute and intensive care on April 1 up to 124 on June 30.

Wachter also said that the number of people admitted to UCSF hospitals because of COVID, as opposed to being admitted for other reasons and later testing positive, is lower than it was over the winter. The ratio is now about 50/50; in January, two-thirds of COVID-positive patients were there to be treated for COVID complications, Wachter said.

Wachter suggests that people trying to judge their risk of catching COVID-19 at a given gathering consider the asymptomatic test positivity rate, the percentage of people tested at the hospital who have no symptoms and end up testing positive. Right now, 6.5% of asymptomatic people getting tested at UCSF are positive for COVID-19, a slight uptick from 5% to 6% over the past two months, Wachter said.

“If 6.5% of an asymptomatic population has Covid, in a crowd of 50 people, there’s a 96.% probability that someone there is positive,” Wachter tweeted.

What’s the takeaway from all of this? Get vaccinated. While the first and second boosters may not prevent you from actually catching the virus, Wachter said the latest data from the CDC on the second booster shows a significant reduction in getting very sick or even dying.

“Many ask: ‘Shouldn’t I wait on boost #2 until fall, when a new bivalent (combo of original & Omicron-specific boost) is available?” Wachter wrote. “For those over 50, I’d say no – there’s too much Covid around and evidence of benefit from boost #2 is persuasive.”

If you want to take more precautions, you can avoid indoor dining and continue to wear an N95 mask in crowded indoor spaces until cases come down.

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