An early glimpse of omicron's threat: High transmission likely, but vaccines provide hope

Researchers are still piecing together data, early anecdotal evidence and existing COVID-19 knowledge to better understand the new, mutated omicron variant of the coronavirus. But less than two weeks into the global effort, those clues are giving experts a glimpse of the variant's threat.

The consensus so far: Vaccines will likely continue protecting against severe disease, but the variant may prove highly infectious, even among people who are fully vaccinated or have been previously infected.

The variant is currently driving an explosion in cases in South Africa, and omicron has already spread to dozens of countries, including the U.S.

Cases in South Africa have more than tripled in four days despite relatively high levels of immunity. Currently, in South Africa, approximately 30% of the population has been fully vaccinated and close to 40% have had clinical COVID.

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"It's exponential growth. From a thousand, you go to 3,000 or 4,000 to 6000 and yesterday 11,000 infections being reported in a single day," said Sikhulile Moyo, laboratory director for the Botswana Harvard HIV Reference Laboratory in Gaborone, Botswana, and research fellow in the Department of Immunology and Infectious Diseases at Harvard T.H. Chan School of Public Health, on a conference call.

Researchers have repeatedly cautioned the variant is so new there's very little they can say definitively.

"It's still very, very early. You must take that with a grain of salt, it's only been a week and a half," said Moyo, who first spotted the variant in Botswana.

Omicron appears to be highly infectious

While data is still coming in, "in terms of transmission, we are seeing an explosion in southern Africa," Moyo said.

The rapid uptick in cases in South Africa coupled with reports of super-spreader events has helped validate experts' early concerns the variant's many mutations would help it spread rapidly.

"That's the most concerning feature that we're seeing right now," said Dr. Roger Shapiro, a professor of immunology at the Harvard Medical School who also works in Botswana, speaking on a conference call with reporters.

This is born out by early anecdotal evidence, including a Christmas party on Nov. 26 in Norway, in which out of 120 fully-vaccinated people, at least 50 have so far been confirmed to have caught the omicron variant.

The party was held indoors at a harbor-side restaurant in Oslo, a city infection control chief told E24, a Norwegian business newspaper.

The Christmas banquet, held on Nov. 26, was for a Norwegian renewable energy company called Scatec, which has operations in South Africa. Several of the people who attended had recently visited the company's Cape Town office, they told officials.

Local health authorities said so far all those infected had mild symptoms and none had been hospitalized.

Vaccines expected to provide protection from severe disease

While reports of vaccinated individuals contracting omicron appear troubling, health experts are generally optimistic that vaccines will continue to provide protection against omicron.

Still emerging evidence suggests people who are either vaccinated or have recovered from COVID-19 can become infected with omicron but may be less likely to become severely ill.

But severe disease is a particularly tricky topic to quickly assess, Moyo said.

"It obviously takes between 5 to 10 to 15 days to really start seeing increases in hospitalizations or severity of disease," he said.

The early reports of mild disease do match an emerging theory — while omicron may lead to an uptick in infections in vaccinated people, vaccines' protection against severe disease is likely to remain strong.

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That's because the vaccines maximize both arms of the immune system, the cellular and humoral, said Shapiro.

"Even if this new omicron variant can escape the humoral, or antibody, response, the cellular response can kick in and keep the disease to something that's only mild or moderate," he said.

Anne von Gottberg — of the University of Witwatersrand — echoed a similar sentiment at a World Health Organization briefing on Thursday: “We believe that vaccines will still, however, protect against severe disease.”

In the United States, most omicron cases so far appear to be in fully-vaccinated people who only experienced a mild case of COVID-19. That includes the first identified case, in San Francisco.

In Hawaii, a person who had previously recovered from COVID-19 but hadn't been vaccinated developed moderate symptoms.

Too early for certainty about omicron's risks

Early speculation about vaccine protection highlights the problem with assessing omicron right now: Trends are starting to emerge but it's too early to draw conclusions.

As far as is currently known, the best protection is still vaccination, Dr. Anthony Fauci said in a White House press briefing.

"How do we address omicron? We've said it over and over again, and it deserves repeating: If you're not vaccinated, get vaccinated. Get boosted if you are vaccinated," he said.

In a press briefing Friday, Fauci presented slides showing the increasingly high levels of antibodies after each shot of vaccine.

"When you look at the third dose, you increase the levels of neutralizing antibodies against all the variants," he said, noting that median antibody levels jumped after the third dose of the Pfizer-BioNTech shot.

There's good reason to believe being vaccinated and boosted provides "some degree of cross-protection, very likely against severe disease, even against the omicron variant," he said.

But he cautioned conclusive findings are weeks away, saying most of what's known now is "breadcrumbs."

"Be careful about breadcrumbs. They may not tell you what kind of loaf of bread you have," he said. "It's just too early to make a definitive prediction about what the severity is going to be."

What the future holds will become much clearer within the next two to three weeks as researchers grow the virus in the lab and test it against antibodies, as well as conduct epidemiological studies to see whether omicron causes severe disease and if so, in whom.

In the worst-case scenario, omicron or some other variant will turn out to be more transmissible, more efficient at making copies of itself and more dangerous, said Dr. Bruce Walker, an immunology professor at Harvard Medical School and the Massachusetts Institute of Technology.

In the best-case scenario, new variants may be more transmissible, but less dangerous, essentially turning themselves into a harmless vaccine that protects against future infection with a similar coronavirus, he said.

"That's very much wishful thinking right now," Walker said, "but it's possible."

Contributing: The Associated Press. Reach Elizabeth Weise at eweise@usatoday.com.

This article originally appeared on USA TODAY: Omicron variant likely spreads fast; COVID vaccine optimism