By LAURAN NEERGAARD ​​and CARLA K. JOHNSON, AP Medical Editors

The new omicron variant only took a few weeks to live up to dire predictions of its contagiousness, but scientists are not yet sure if it is causing more serious illness even as the world grapples with cases. explosives just before Christmas.

“Everything is riskier now because omicron is so much more contagious,” said Dr. S. Wesley Long, who heads the testing lab at the Methodist Hospital in Houston – and over the past week he tried to stay home as much as possible to avoid exposure.

Public health officials are struggling to keep up with the speed at which omicron is spreading nationally and globally. But in three weeks, omicron now accounts for 80% of new symptomatic cases diagnosed by Houston Methodist testing sites. It took the also highly contagious delta variant three months to reach that level, Long said.

Authorities expect Omicron to become the dominant mutant in the United States within weeks, as it has already taken over in Britain.

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What this will mean for the world is still unclear as so many questions remain unanswered. Here is the latest information on what is known and what remains to be learned about omicron.

HOW MUCH PROTECTION DO VACCINES OFFER?

Vaccines in the United States and around the world do not offer as much protection against omicron as against previous versions of the coronavirus. However, vaccines still help – a lot. Laboratory tests show that although two doses are not strong enough to prevent infection, a booster of Pfizer or Moderna vaccine produces anti-virus antibodies capable of fighting omicron.

Antibody levels naturally drop over time, and a booster kicked them up, 25 times for Pfizer’s extra shot and 37 times for Moderna’s. No one knows exactly what level is high enough – or how long it will take before antibody levels start to drop again.

After a booster, the protection against an omicron infection still appears about 20% less than the protection against the delta variant, said Dr. Egon Ozer of Northwestern University.

But if the virus goes beyond this first line of defense, those vaccinated have additional layers of protection.

“The vaccines will protect you against serious illness, hospitalization and death,” Houston Methodist Long said. “And that is really the most important thing.”

These additional defenses include T cells that work together to repel the virus, as well as memory cells that, when reactivated, rush to make more and more powerful antibodies.

WHAT ABOUT NATURAL IMMUNITY?

A previous infection does not appear to offer much protection against an omicron infection although, as with vaccination, it may reduce the risk of serious disease.

In South Africa, where omicron has already spread widely, scientists have reported a surge in re-infections that they had not seen when two previous mutants, including delta, moved across the country.

In Britain, a report from Imperial College London on Friday found that the risk of re-infection with omicron was five times higher than the previous delta variant.

Health experts say anyone who has survived a COVID-19 crisis should still get the shot because the suit usually offers stronger protection.

WHY ELSE IS OMICRON SPREAD SO FAST?

Scientists are trying to decode the dozens of mutations omicron carries to understand what else is going on. Researchers in Hong Kong recently reported clues that omicron may multiply faster in the airways than delta, but not as efficiently in the lungs.

What scientists can’t measure is human behavior: Many places loosened restrictions, winter forced indoor gatherings, and travel surged as the omicron began to spread.

DOES OMICRON CAUSE LOWER ILLNESSES?

It is still too early to know, especially since if the vaccinees contract an infectious infection, it should be milder than if omicron attacks the unvaccinated.

The first reports from South Africa suggested milder disease, but doctors weren’t sure if that was because the population was quite young – or that many retained some protection against a recent delta infection.

And this British study found no evidence that omicron was milder than delta in Britain, even in young adults – who are expected to have milder disease – with higher infection rates with l ‘omicron.

“There’s a clue, and I think a lot of us are hopeful that the omicron will be any less serious. But I don’t think we can bet the farm on it. We’re still talking about SARS-CoV- 2, a virus that has killed millions of people, ”said Dr. Jacob Lemieux, who is monitoring variants for a research collaboration led by Harvard Medical School.

According to the behavior of other variants, “If you’re older, if you have underlying conditions, if you’re obese, you’re more likely to have serious disease.” I don’t think it will be any different “from the other variants,” said Dr Carlos del Rio of Emory University.

But even if you don’t get very sick, an omicron infection could definitely ruin the vacation. Experts agree that in addition to getting vaccinated and boosted, it’s wise to go back to basics of protection: wearing masks indoors, avoiding crowds and keeping your distance.

Associated Press science editor Laura Ungar contributed to this report.

The Associated Press’s Department of Health and Science receives support from the Department of Science Education at Howard Hughes Medical Institute. The AP is solely responsible for all content.

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