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Delta is 'optimized for infecting humans,' but vaccines are the way out

Coronavirus variants are opening up a worrying new front in the pandemic, but one expert says vaccines can still beat the ever-changing threat.

For the most up-to-date news and information about the coronavirus pandemic, visit the WHO and CDC websites.

After close to a year and a half of pandemic turmoil and more than 200 million confirmed COVID cases worldwide, health officials are sounding the alarm about a new and evolving threat facing the world: the rise of virus variants, including the delta strain. 

"It's doing almost everything that we've been worried about," says Andy Pekosz, professor of microbiology at the Johns Hopkins Bloomberg School of Public Health. 

"It's spreading more efficiently in the population, it seems to be causing more disease across a number of age groups, and it seems to be escaping some of the immunity that our vaccines are able to generate against the virus. It really is a virus that seems to be optimized for infecting humans."

The delta variant is now the dominant strain in the US, accounting for roughly 80% of new cases. And when it comes to this new strain, unvaccinated members of the public are a major concern, not just because they're far more likely to become infected with the virus. Pekosz says unvaccinated pockets of the community also give the virus a greater chance of spreading and mutating, thereby increasing the risk of creating new variants that are better at infecting humans. 

"Replication in unvaccinated people is allowing the virus to generate a whole panel of variants," says Pekosz. 

"When you have lots and lots of people getting infected and making lots and lots of virus, there's just more chance that the virus can mutate. Every once in a while these random mutations give the virus what's called a 'fitness advantage,' meaning it allows the virus to do something a little bit better, which allows it to spread in the population. [That's] what we've seen with delta."

Though Pekosz says vaccines may be slightly less effective against these new variants, vaccination is still the number one tool we have to fight the virus, in all its forms. 

"We know what it takes to get a vaccine to work against COVID-19," he says. "Even if the viruses change, we can adapt to that very quickly and keep the vaccines up to date with strains that are circulating.

"There really is light at the end of the tunnel. There really is a path forward. We just have to be better and more effective at using the tools that we have right now to keep this virus down."

Andy Pekosz shared a raft of insights on the new coronavirus variants with CNET's Claire Reilly -- including how we can beat delta and what individuals can safely do as we start to contemplate a return to work, school and travel. You can check out the entire conversation in the video above.