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The virus that causes COVID-19 changes all the time. In most cases, the changes are harmless. But they can add up. And when they do, the virus can become more contagious or deadlier, and potentially evade vaccines, treatment, diagnostics or natural immunity.

We know that a number of these potentially more dangerous or difficult variants are circulating in the U.S. in increasing numbers. But scientific leaders say there's no reason to panic about the variants yet.

Instead, what needs to happen is more research into the potential risks of these variants, better tracking of these changes and a doubling down on protection efforts that we know work, including wearing face masks, avoiding crowds, and getting vaccinated as soon as possible.

President Joe Biden also reinstated travel restrictions Monday to combat the highly contagious variants. The restrictions apply to non-U.S. citizens who have been in Brazil, Ireland, the United Kingdom, much of Europe, and soon, South Africa.

Here, USA TODAY answers common questions about these variants:

How dangerous are these variants?

The short answer is we don't really know yet. 

Several, including ones first seen in the United Kingdom, South Africa, Brazil and California, appear to be more contagious, but not necessarily deadlier. That is, out of 100 people who catch any variant of the SARS-CoV-2 virus, one to two people are likely to die. 

But these variants can still kill more people. If 200 people catch it instead of 100, then two to four people will die.

And if hospitals are overwhelmed with COVID-19 patients, doctors and nurses won't be able to provide as high-quality care for those patients or others who come in with different problems, such as heart attacks and injuries from accidents.

Do the Pfizer-BioNTech and Moderna vaccines protect against the new variants?

Yes. So far, both vaccines authorized for use in the United States – one by Pfizer-BioNTech and the other by Moderna – appear to be effective against the known variants. 

Moderna said its COVID-19 vaccine protects against the two variants that emerged from Britain and South Africa, though not as strongly against the variant in South Africa, according to a company study.

The biotechnology firm said in a statement Monday that its vaccine produced an immune response to “all key emerging variants tested” and no significant reduction in neutralizing antibodies against the variant first identified in the U.K.

In a lab dish, blood from people who received the vaccine was far less efficient at making neutralizing antibodies against the South African variant than the original virus. But Moderna said those were still "above levels expected to be protective.

Nonetheless, the company is developing a booster dose that could combat the South African variant and future emerging ones.

Pfizer-BioNTech, which makes a similar COVID-19 vaccine, says its shot appear to be effective against the variant from Britain, although the company has not yet studied other variants.

Symptoms: Is there any way to identify the new variant?

No. Even standard diagnostic tests cannot differentiate among variants.

The only way to identify a variant is by sequencing its genes using samples from people who are sick.

Why are they called variants and not strains? 

Generally, researchers consider something a new "strain" when it is substantially different than an existing version.

The flu, for instance, comes in different strains every year. Protection against one strain won't necessarily protect against another, which is why we need a flu shot every year. 

So far, though, the differences we've seen in SARS-CoV-2 aren't dramatic enough to call them a new "strain." Instead, the scientifically appropriate term is "variant." 

A single mutation is typically not enough to qualify something as a new variant. The variants that have raised concern all have more than a dozen mutations and some nearly two dozen mutations.

Where do the names come from?

Scientists don't like to name variants after the places where they are first seen because that can penalize locations with better testing and research. Instead, they name the variants after the locations of genetic changes in the virus.

“They're still sorting out naming conventions,” said Daniel Parker, an assistant professor of public health at the University of California, Irvine. “It is a bit confusing for everyone right now.”

Are the variants in the US? Where?

According to the Centers for Disease Control and Prevention, nearly 300 cases of the U.K. variant have been reported in at least 24 states. So far, Florida has reported the most cases with 92. California follows closely behind with 90 reported cases.

Experts say the British variant will probably become the dominant source of infection in the United States by March.

The first case of the variant initially discovered in Brazil was detected Monday in a Minnesota resident who recently traveled to the country.

The South African variant has yet to be discovered in the U.S., however, experts don’t dismiss the possibility that it’s already here. They say lack of genetic sequencing in COVID-19 testing fails to capture the true number of cases of these emerging variants.

Are there any variants that originated in the United States?

Yes. The U.S., which has the world's worst outbreak, is likely a major breeding ground for mutations.

"Eventually, you'd expect some of these mutations to result in advantage for the virus," said Dr. Robert Bollinger, a professor of infectious diseases at Johns Hopkins School of Medicine.

In mid-January, officials began raising concerns about a variant first seen in California, called B.1.429. It is potentially more infectious but has not been seen to be more dangerous in terms of causing more serious illness or death. 

A mutation in the variant was first detected as long ago as last March but appears to have been very rare until November.

Between Nov. 22 and Dec. 13, the variant made up 3% of California cases where the virus had been genetically sequenced. Between Dec. 14 and Jan. 3, that rose to 25%, said Dr. Charles Chiu, a professor of medicine and expert in viral genomics at the University of California, San Francisco.

There is some concern that the parts of the virus that are mutating might have an effect on the effectiveness of vaccines, but the data so far is very preliminary, Chiu said.

“The takeaway is not that we need to start worrying about this,” said Dr. Sara Cody, health officer and director of public health for Santa Clara County, which encompasses Silicon Valley. “The takeaway is that we need to lean in and learn more about it.”

Are two masks better than one?Double masking 'just makes common sense' to help prevent COVID-19 spread, Fauci says

What about the British variant?

U.K. officials said last week that the B.1.1.7 variant might actually be deadlier, in addition to more contagious, though the data are inconclusive.

British Prime Minister Boris Johnson announced last week that the British variant, believed to be more infectious, is also killing a higher percentage of its victims.

For 1,000 people age 60, approximately 10 people would be expected to die, he said. With the new variant, called B.1.1.7, roughly 13 or 14 people are dying, he said, citing data from the New and Emerging Respiratory Virus Threats Advisory Group, which advises the United Kingdom government.

"I want to stress there's a lot of uncertainty around these numbers and we need more work to get a precise handle on it, but it obviously is a concern that this (variant) has an increase in mortality as well as an increase in transmissibility," said Sir Patrick Vallance, Johnson's chief scientific adviser.

The South African variant is raising a lot of concerns. Why?

The 501Y.V2 variant, first identified in South Africa, appears to be about 50% more contagious, meaning it does a better job than the original virus at getting into human cells.

It appears to attach more strongly to human cells than the original SARS-CoV-2 virus, said Salim Abdool Karim, a clinical infectious diseases epidemiologist at the Mailman School of Public Health at Columbia University and a pro-vice-chancellor at the University of KwaZulu-Natal in Durban, South Africa. 

The variant discovered in South Africa, which has a mutation called 484, may be escaping some or all of the antibodies people developed against a natural infection.

Looking at blood from 44 South Africans who recovered from COVID-19, more than 90% showed reduced immunity to the new variant, and almost half had no protection at all against it, according to a study published recently though not yet peer-reviewed.

The true test of whether a virus has "escaped" immunity is whether people can be re-infected. In South Africa, "the data at this point do not point in that direction," Karim said.

The Moderna vaccine is likely to be somewhat less effective against the South African variant than the original virus, although in a lab dish its vaccine was still able to neutralize virus with that variant, according to the company.

"While the current strains appear to be well protected by our COVID-19 vaccine, as we continue to follow the story in the weeks, months and potentially years ahead, it's important that we remain vigilant and develop tools and countermeasures that would allow us to continue to beat back the pandemic," said Moderna President Stephen Hoge.

Moderna is developing a version of its vaccine to specifically target the South African variant, to show that it can quickly tweak its vaccine. This would be delivered as a booster shot, in addition to the two-dose vaccine currently being distributed.

Company officials said they are confident that they can meet the demand should a booster like this become necessary.

Your coronavirus questions, answered:What you need to know about COVID-19

What about the Brazilian variant?

Scientists are concerned the variant that first arose in Brazil might not be controlled by natural immunity – that is, someone once infected by SARS-CoV-2 might be vulnerable to another infection with the new variant.

In Manaus, a 29-year-old woman who had COVID-19 in March caught a different variant in December, according to a recent case study. The woman had been healthy prior to her first infection with no immune issues.

This raises the possibility that natural infections will not contribute to herd immunity, the level of protection needed to stop the spread of a virus.

Does double masking make sense? Will N95, KF94 masks protect me?

The gold standard N95 masks are still hard to find and should be reserved for health care workers on the frontlines of the pandemic.

Experts say the KF94 mask, from South Korea, is a close second. Dr. Ashish Jha, dean of the Brown University School of Public Health, told The New York Times that the KF94 mask is made up of a similar material as the N95 and blocks 94% of viral particles. But one notable difference is that the KF94 has ear loops instead of elastic head bands.

Double masking – wearing two masks instead of one – has gained renewed momentum after several high-profile officials and celebrities were seen wearing two masks at President Joe Biden’s inauguration last week.

Dr. Anthony Fauci, the nation’s top infectious disease expert, said Monday on "NBC News’ "TODAY” that two masks are always better than one.

“If you have a physical covering with one layer, you put another layer on, it just makes common sense that it likely would be more effective,” he said. “That’s the reason why you see people either double masking or doing a version of an N95.”

A study published in the peer-reviewed journal Matter in July found that wearing two masks could increase protection from virus particles by 50% up to 75%.

However, experts are less concerned about double masking and more concerned about people who aren’t masking at all.

“The idea of double masking just simply means that you’re paying attention to wearing a better mask that you might have been before,” said Emory University infectious disease expert Dr. Colleen Kraft. “If people would just wear masks in general, we would actually be fine against the variants.”


What is being done or can be done to stop these variants?

Slowing the pandemic is the best way to stop these variants and any future ones, scientists say.

The more the virus is allowed to spread, the more likely variants will continue to evolve.

The best ways to stop transmission are mask wearing, hand washing, avoiding crowds and getting vaccinated as soon as possible, scientists say. 

The Biden administration is expected to increase surveillance for the variants, and companies are stepping up efforts to be prepared in case vaccines need to be changed to better target these variants. 

Contributing: Kim Hjelmgaard and Elizabeth Weise, USA TODAY.
