Despite COVID-19 vaccines now being largely available, lagging vaccination rates create opportunities for the coronavirus to mutate and evolve into more dangerous versions.

“I think we just need to tap the brakes a little bit and get into the new world of expectations of COVID,” Dr. Michael Saag, associate dean for global health at the University of Alabama at Birmingham, said on Yahoo Finance Live (video above). “COVID is going to be with us for years to come, and we’re going to see variants emerge. And we’re going to go through this process several times, maybe many times in the future.”

In the U.S. and other countries with mass vaccination capabilities, most of those who are unvaccinated are that way by choice. In some other parts of the world, it’s often an issue of accessibility.

The Omicron variant, recently dubbed a “variant of concern” by the World Health Organization (WHO), was first reported out of Southern Africa, though it’s unclear whether or not that’s where it actually originated. Vaccination rates in the region are below the global average of 56% — in Botswana, the rate is at just 40% while South Africa’s is 30%. (Reports have indicated the variant has now been detected in the U.S. as well.)

“This coronavirus appears to go through populations, especially of the vulnerable,” Saag said. “In this case, nowadays, I mean the immune naive — that’s people who have never been vaccinated, who have never had the infection in particular. That’s like tinder for a fire. It’s cannon fodder. The virus, as soon as it gets an opportunity, is going to rummage right through that population and it changes. It mutates as it goes.”

Early reports suggest that Omicron is spreading quickly but cases tend to be more mild, and Pfizer CEO Alberta Bourla pointed out that the ongoing spread provides more opportunities for mutations.

“I don’t see any indication that this virus is going to extinguish itself, at least not in the next year or two,” Saag added. “So I think we need to be prepared for that. What can we do? Get vaccinated. It’s very simple.”

'Their body basically is a reservoir'

About 60% of the U.S. population is fully vaccinated while 71.1% have received at least one dose. Booster shots are now available as well — 21.7% of Americans have gotten theirs.

And while countries such as Portugal, Singapore, and the United Arab Emirates have fully vaccinated rates of 87% or higher, countries like Burundi, Congo, Haiti, and Chad are at less than 1%.

“They’re unvaccinated,” Campbell said. “Their body basically is a reservoir. Basically, the virus is having a field day inside their immune system and has a chance to mutate whereas when you’re vaccinated, your body will have antibodies. There are B cells, there are T cells, all of the things that are good that help you fight it. That’s what you want to have. That’s why we have to get people vaccinated.”

Viruses mutating into other strains isn't new — the flu virus is constantly evolving, which is why there are new shots to get each year. The difference with this Omicron COVID variant versus others is its number of mutations.

“Instead of it having 20 mutations or 19 mutations like Delta, this one has about 30 to 40 in it,” Campbell explained. “That’s why everybody’s nervous about what’s going on. But the first thing is not to panic. Make sure, no. 1, the message is: Get vaccinated or get boosted and get ready."

'Get your boosters'

Vaccination rates in the U.S. ticked up in recent weeks amid vaccine mandates, concerns surrounding the Delta variant, and the upcoming winter months.

“For Delta, at six months since your last shot, your immunity goes down,” Dr. Andre Campbell, an ICU physician and trauma surgeon at Zuckerberg General Hospital, recently said on Yahoo Finance Live. “That’s why it went from the protection of 90% down to 50%. That’s why that booster then brings you back up to 95%. That’s what you really want.”

Campbell stressed: “Get your boosters. Then two weeks after, you’ll be fully vaccinated because your body will get revved up against it.”

Adriana Belmonte is a reporter and editor covering politics and health care policy for Yahoo Finance. You can follow her on Twitter @adrianambells and reach her at adriana@yahoofinance.com.

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