When it comes to the new Omicron variant of COVID-19, there’s a lot that experts still don’t know. But the one thing is clear at this point: it’s highly contagious.

In a week, Omicron went from accounting for 12.6% of all reported U.S. cases of COVID-19 to 73.2% as of Dec. 18, according to the Centers for Disease Control and Prevention. “That tells you how transmissible it is,” says Mark Dybul, a Georgetown University professor and immunologist who serves as CEO of Enochian BioSciences.

And those numbers might even be hiding how vast the true spread really is, according to Dybul. “I would bet 60% to 70% of New York City is infected if we actually tested those who are asymptomatic,” he said. “The number of new [Omicron] infections is doubling every couple of days.”

But predicting how severe this latest variant will be for the U.S. is still hard to tell. “You can't predict this one,” Dybul says. Right now, the data from Southern Africa shows there are fewer hospitalizations and deaths as a result of Omicron compared to other variants.

“So far, the death rate is barely bumping. Yes, hospitals are getting overwhelmed with people with flu-like symptoms who are sick and scared. It's not people going to the ICU,” Dybul says. But that may change as more cases are reported and infection cycles play out. For instance, there's typically a lag between infection rates spiking and death rates following suit.

But the severity of even the current cases shouldn’t be diminished. “People are getting really sick, just as they did with Delta. They just weren't being hospitalized. But there were people out from fatigue for two months,” Dybul says. “That's happening with Omicron as well. People are going to get very sick. They're just less likely to be hospitalized or die, especially if they're boosted.”

Currently, Pfizer and Moderna COVID vaccines are less effective against preventing Omicron infection, but they are still about 70% effective at preventing severe infection and hospitalization, according to self-reported testing from the companies and independent research. That protection increases among those who received a booster, but particularly for people who received a Moderna booster, the company reported on December 20. White House Press Secretary Jen Psaki said on December 21 that those who are unvaccinated are 14 times more likely to die from COVID than those who are vaccinated.

“In the United States, people currently in the ICUs are almost uniformly unvaccinated,” Dybul says. But it’s too early to tell if that pattern will continue. “We'll know a lot from Europe in the next few weeks because they're hitting their peak now, especially in terms of hospitalization death rates. In the next two weeks, we will have the answer.”

How should Americans respond to Omicron now?

But what does that two week window mean for the U.S., especially as Americans approach the end-of-the-year holidays when people are more likely to travel and gather together?

“We have to assume the worst,” Dybul says, adding Americans should plan for Omicron to be as bad or worse than Delta’s severity. But Dybul says the situation is actually manageable.

“We don't have to panic if we actually respond now. We need basic good public health measures, which is not shutting everything down,” Dybul says.

That means that the U.S. needs to focus on getting everyone a vaccine and a booster within the next six months. “There's going to be a lag there because so much of our population didn't get a second dose until the summer or later, but you know, everyone needs to get it and that will do a lot of protection,” Dybul says.

Second, he says everyone needs to be wearing masks in public spaces and indoors—KN95 quality or better if possible, which would be an N95. If you’re outside and it’s crowded, you should be wearing then, too. If you're walking down the street, you probably don't need a mask, but Dybul says it might help get people to wear masks as much as possible.

Lastly, Americans need regular testing. Schools and businesses have shown that with regular testing, the U.S. can keep moving. “I'm traveling for the holidays, and we're testing every day,” Dybul says.

On December 21, President Joe Biden pledged to purchase 500 million rapid, at-home tests and distribute them for free. Starting in January, Americans will be able to log onto a new federal website and order free tests sent to their homes. The administration is also planning to set up a number of new federal testing sites around the country, the first of which is planned to launch in New York City this week. Currently, the U.S. has about 20,000 free testing sites.

“What we need is a massive amount of home-based rapid tests and we should all be testing regularly,” Dybul says. “This thing is gonna spread like wildfire. So we need to take action so that we don't have that panic, so we don't have another economic catastrophe.”

Looking ahead, summer is likely going to be worse

Omicron is already at least a partially vaccine-resistant variant, as it seems to be successfully evading vaccines. It's important to note, though, that vaccinations are still critical for avoiding the most serious cases. “There's still a lot of immunity around that keeps you from getting really sick and dying, at least as long as so it's partially resistant,” Dybul says.

But he expects to see a fully resistant COVID variant emerge between March and May of 2022. “It’s inevitable,” Dybul says of the rise of a variant that escapes the current vaccines.

“We are going to have variants, continual variants that become more and more resistant to our current vaccine, Dybul says. “The question is at what speed will that happen.”

When that does happen, Pfizer, Moderna and other producers will have to generate a second generation of the vaccine, which would likely take around 100 days to launch production. With a fully vaccine-resistant variant, masking, social distancing and general good hygiene habits will become more important. Oral medications, including those by Pfizer and Merk, and other treatments in development now may also prove helpful.

Still, if Dybul’s prediction holds true, summer 2022 is looking to be a crazy time.