America is in a race to vaccinate people before the country is overwhelmed by variants that are spurring a fourth wave of COVID-19.

Why it matters: Spring is here, and when cases were dropping, hope was rising for a more normal summer. But experts warn this will only happen if people keep social distancing, wearing masks and getting vaccinated as soon as they can.

State of play: Growing evidence shows the three authorized vaccines currently offer protection against the variants, Larry Luchsinger, assistant member of the nonprofit New York Blood Center, tells Axios.

• But Luchsinger and several other experts warn vaccinations must speed up in the U.S. and globally before a more serious variant pops up that renders the first generation of vaccines ineffective.
• Experts aren't the only ones worried: A recent Harris poll finds a majority of Americans from all political parties are either "somewhat" or "very" concerned about the variants.

What's happening: Viruses constantly mutate, mostly without public health impact unless the changes converge on a trait that is advantageous to the virus. For the most part, those changes haven't made a big impact on SARS-CoV-2.

• None of the currently circulating variants have been labeled by the CDC as being of "high consequence," which would require serious medical countermeasures.

Yes, but: The agency is watching five "variants of concern" that can alter public health measures by having characteristics such as increased transmissibility, more severe disease or a higher death rate, and the ability to interfere with treatments or vaccine effectiveness.

• Those five variants, and the places they were originally detected, are: B.1.1.7 (U.K.), P.1 (Japan/Brazil), B.1.351 (South Africa), B.1.427 (California), and B.1.429 (California).

"The B.1.1.7 is a superspreader, in a way. It has a higher chance of spreading — about 50% to 70% more likely," says Ali Mokdad, professor of health metrics sciences at the IHME at the University of Washington.

• This variant is primarily responsible for the rise in several hotspots in New York, Michigan, Wisconsin and elsewhere, Mokdad tells Axios.
• B.1.1.7 tends to dominate other variants in a community, has been found to roughly double every 7–10 days, and is now about 26% of cases in the nation.
• Good news: The vaccines are effective against it. Bad news: It's more infectious and can cause worse complications or death. Plus, only about 150 million doses of COVID-19 vaccines have been given in the U.S. so far.
• "Basically, we're in a race against time, where we need to make sure everybody who's eligible to a vaccine has access and gets it in order to ensure that cases will keep falling all the way until the end of the summer," Mokdad says.

The California variants (B.1.427 and B.1.429) are about 20% more transmissible than the original SARS-CoV-2, "but the vaccines are still fantastic and are doing a really good job," says Stacia Wyman, a genomics researcher who leads the sequencing effort in UC Berkeley’s Innovative Genomics Institute.

• "But I'm a little bit worried because I feel like places have been opening up too early. Just because cases are going down, doesn't mean it's safe to eat inside next to someone or go to a bar," Wyman adds.

The South Africa and Brazil variants (B.1.351 and P.1) appear to render the current vaccines slightly less effective in experimental data. B.1.351 is also about 50% more transmissible, but the rate for P.1 is not yet known, per the CDC.

• "The B.1.1.7 seems to be edging out the B.1.351 and the P.1 at least for now. Although they are concerning, they are not playing a big role in our epidemiology right now," Caitlin Rivers, senior scholar at the Johns Hopkins Center for Health Security, tells Axios.

Of note: Mutation E484K, nicknamed Eek, is also under close watch.

• It's "especially concerning" because it's popped up in different variants (B.1.351, B.1.1.28 and now B.1.1.7), can help the virus evade the immune system, and may become resistant to current vaccines and monoclonal antibody treatments, says Allison Greaney, graduate student researcher at Fred Hutchinson Cancer Research Center.

What's next: Strengthening the U.S. genomic surveillance strategy and contact-tracing programs is key, according to Rivers. The American Rescue Plan Act had $1.75 billion for surveillance that "will boost our capabilities," she says.

• Developing new technologies to explore the role a person's biomarkers or other characteristics play in leading to differing responses to the virus and its variants would be "a real leap of technology," Luchsinger says.
• Second-generation vaccines are already under development. For example, Moderna just started the Phase 1 clinical trial of its COVID-19 variant vaccine that aims to address key mutations from the South African variant.

The bottom line: "Summer could be very good for us, as long as we behave for the next couple of weeks" with social distancing, masking and getting vaccinated, Mokdad says.

Go deeper: Check out our new, live Coronavirus Variant Tracker.