Most of the COVID-19 cases that Dr. Gary Green treats those days on an outpatient basis are akin to busy occasions and the kinds of things Americans are doing more and more as summer progresses.
In the case of the highly infectious SARS-CoV-2 coronavirus, this can lead to infections.
Green, an infectious disease specialist at Sutter Health, says he’s seeing a steady flow of cases, though not many, and that severe symptoms requiring hospitalization are rare.
Rising herd immunity, increased activity driven by warmer weather and an aging population that has “taken” protective measures are all contributing to a “pause” in cases, Green said.
But new COVID-19 subvariants threaten to increase viral transmission this summer, fall and winter.
KP. 2, the most prolific of the so-called “FLiRT” subvariants, and lately the most dominant subvariant in the United States, is a fourth- or fifth-generation strain of the omicron variant. It is a descendant of the JN. 1 strain of Omicron.
In less than two months, between late March and early May, KP. 2 infections rose from 4% to about 28% in the U. S. According to the federal Centers for Disease Control and Prevention.
Green said that, as with previous subvariants of SARS-CoV-2, the virus that causes COVID-19 disease, KP. 2 has mutated spike proteins that allow it to bind more effectively to the respiratory epithelium, protecting it from inhaled pathogens and irritants.
Unfortunately, this is part of the natural evolution of those subvariants, he said.
“We’re hoping that those viruses will be a little bit more effective at spreading, transmitting and attaching them,” Green said.
“But the good news is that it occurs more commonly in the upper respiratory tract, where you feel like you have a cold, and not so much in the lower respiratory tract, where you feel like you have pneumonia,” he said.
“This doesn’t make the virus more dangerous,” Green added. “So, we don’t expect more severe cases, but it may be a little more contagious. “
Green said the existing vaccine appears to offer some coverage unlike the new variants.
Dr. Tanya Phares, Sonoma County Health Officer, echoed Green’s comments related to subvariants. “Despite increased transmissibility, those mutations do not appear to result in more severe disease,” he said in an email.
Phares said that between late March and early May, eight instances of the FLiRT subvariants were genetically sequenced. The FLiRT subvariants are descended from the JN. 1 subvariant, which remains the dominant strain in Sonoma County and the state, fitness officials said.
In Napa County, the most prevalent subvariants since April have been KP. 2 to 7 percent, KP. 3 to 4 percent and KP. 1. 1 to 3 percent, according to county fitness officials.
Dr. Michael Vollmer, an epidemiologist at Kaiser Permanente Regional Hospital, said the most recent FLiRT mutations are “not unexpected” and fit a trend of viral evolution that occurs every three to six months as the virus circulates around the world.
“The virus still requires tactics to replicate,” Vollmer said, adding that the existing, though related, mutations “look very different” from those circulating a year or two ago.
“But what we’re seeing right now is an increase in cases of severe illness,” he said. “Unlike 2021, we expect to see a sharp increase in emergency room or hospital admissions over the summer. “
Vollmer said it’s harder to wait for what will happen in the fall and winter.
It’s important for people to understand that COVID-19 may not lead anywhere and that while its overall effect is rarely as severe as it once was, the virus is still dangerous for people over the age of 65 or those who are “severely immunocompromised,” he said.
“Those who stay up to date on their vaccinations will get better results,” Vollmer said. “People, especially those in those vulnerable categories, deserve to make sure they’re up to date on their vaccinations, as they could get repeat doses. “
Vollmer said he expects vaccine makers and federal regulators to meet this month to discuss the COVID-19 vaccine update for the fall and winter seasons.
It’s possible that the next two to four weeks of the summer will see a surge in COVID-19 cases, but that probably won’t have a major impact on the health care system, he said.
Dr. John Swartzberg, an infectious disease expert at the University of California, Berkeley, said the JN. 1 strain of omicron was dominant in the U. S. It was not until about two months ago, when JN. 1 subvariants such as KP. 2 began to gain traction.
The existing vaccine, which became available last October, targets an omicron subvariant known as XBB. 1, Swartzberg said, adding that KP. 2 is more transmissible than JN. 1, which in turn is more transmissible than XBB. 1.
SARS-CoV-2 continues to evolve, as does the pandemic, finding new tactics to evade host immunity, he said.
But Swartzberg noted that there’s little evidence that KP. 2 and the newer JN. 1 subvariants cause more severe disease.
The “good news,” he said, is that the existing vaccine provides some protection.
Swartzberg said last month that the World Health Organization had mandated that the fall vaccine be directed against JN. 1. He said he hopes the U. S. Food and Drug Administration will at least take that step in its recommendations.
“Either they’re going to stick to the WHO and come up with the JN. 1 vaccine, or they’re going to come up with it as opposed to KP. 2, the maximum of the FLiRT variants,” Swartzberg said.
“The good news is that it takes a few months to produce enough vaccines to vaccinate everyone,” he said.
Editor Martin Espinoza can be reached at 707-521-5213 or martin. espinoza@pressdemocrat. com. On Twitter @pressreno.