The new omicron variant took only a few weeks to live up to dire predictions about how hugely contagious it is but scientists dont yet know if it causes more severe disease even as the world faces exploding cases just before Christmas.
Everything is riskier now because omicron is so much more contagious, said Dr. S. Wesley Long, who directs the testing lab at Houston Methodist Hospital and over the past week has tried to stay home as much as possible to avoid exposure.
Public health officials are finding it hard to keep up with just how fast omicron is spreading nationally and globally. But in three weeks, omicron now makes up 80% of new symptomatic cases diagnosed by Houston Methodists testing sites. It took the also very contagious delta variant three months to reach that level, Long said.
Officials expect omicron to become the dominant mutant in the U.S. within weeks, like it already has taken over in Britain.
What that will mean for the world is still unclear because so many questions remain unanswered. Heres the latest on whats known and whats still to learn about omicron.
HOW MUCH PROTECTION DO VACCINES OFFER?
Vaccines in the U.S. and around the world do not offer as much protection against omicron as they have against previous versions of the coronavirus. However, vaccines still help a lot. Lab tests show while two doses may not be strong enough to prevent infection, a booster shot of either the Pfizer or Moderna vaccine produces virus-fighting antibodies capable of tackling omicron.
Antibody levels naturally drop over time, and a booster revved them back up again, by 25 times for Pfizers extra shot and 37 times for Modernas. No one knows exactly what level is high enough or how long it will be before antibody levels begin dropping again.
After a booster, the protection against an omicron infection still appears about 20% less than protection against the delta variant, said Dr. Egon Ozer of Northwestern University.
But if the virus gets past that first line of defense, the vaccinated have additional layers of protection.
The vaccines are going to protect you against severe disease, hospitalization and death, said Houston Methodist’s Long. And thats really the most important thing.
Those extra defenses include T cells that mobilize to beat back the virus, plus memory cells that, once reactivated, race to make more and stronger antibodies.
WHAT ABOUT NATURAL IMMUNITY?
A prior infection doesnt seem to offer much protection against an omicron infection although, like with vaccination, it may reduce the chances of severe illness.
In South Africa, where omicron already has spread widely, scientists reported a jump in reinfections that they hadnt seen when two previous mutants, including delta, moved through the country.
In Britain, a report from the Imperial College of London on Friday found the risk of reinfection from omicron was five times higher compared to the earlier delta variant.
Health experts say anyone whos survived a bout of COVID-19 still should get vaccinated, because the combination generally offers stronger protection.
WHY ELSE DOES OMICRON SPREAD SO FAST?
Scientists are trying to decode the dozens of mutations that omicron carries to figure out what else is going on. Researchers in Hong Kong recently reported hints that omicron may multiply more quickly in the airway than delta did, although not as efficiently deep in the lungs.
What scientists can’t measure is human behavior: Many places were relaxing restrictions, winter forced gatherings indoors and travel has jumped right as omicron began spreading.
IS OMICRON CAUSING MILDER ILLNESS?
Its still too early to know especially given that if the vaccinated get a breakthrough infection, it should be milder than if omicron attacks the unvaccinated.
Early reports from South Africa suggested milder illness but doctors were unsure whether thats because the population is fairly young or that many retained some protection from a recent delta infection.
And that British study found no evidence that omicron has been milder than delta in Britain, even with young adults — who would be expected to have milder illness — having higher rates of infection with omicron.
“Theres a hint, and I think many of us are hopeful, that omicron will be less severe. But I dont think we can bet the farm on that. Were still talking about SARS CoV-2, a virus that has killed millions of people, said Dr. Jacob Lemieux, who monitors variants for a research collaboration led by Harvard Medical School.
WHOS MOST AT RISK?
Based on the behavior of other variants, if youre older, if you have underlying conditions, if youre obese, youre more likely to have severe disease. I dont think its going to be any different than other variants, said Dr. Carlos del Rio of Emory University.
But even if you dont get very sick, an omicron infection could certainly ruin the holidays. Experts agree that in addition to getting vaccinated and boosted, it’s wise to get back to the basics of protection: Wear masks indoors, avoid crowds and keep your distance.
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Associated Press Science Writer Laura Ungar contributed to this report.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institutes Department of Science Education. The AP is solely responsible for all content.
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