Scientists working at computers, wearing masks.
Scientists working at computers, wearing masks.
Scientists working at computers, wearing masks.

COVID Variants: What You Should Know

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In December 2020, news media reported a new variant of the coronavirus that causes COVID-19, and since then, other variants have been identified and are under investigation. The new variants raise questions: Are people more at risk for getting sick? Will the COVID-19 vaccines still work? Are there new or different things you should do now to stay safe?

Stuart Ray, M.D., vice chair of medicine for data integrity and analytics, and Robert Bollinger, M.D., M.P.H., Raj and Kamla Gupta professor of infectious diseases, are experts in SARS-CoV-2, the virus that causes COVID-19. They talk about what is known about these new variants, and answer questions and concerns you may have.

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Coronavirus Mutation: Why does the coronavirus change?

Variants of viruses occur when there is a change — or mutation — to the virus’s genes. Ray says it is the nature of RNA viruses such as the coronavirus to evolve and change gradually. “Geographic separation tends to result in genetically distinct variants,” he says.

Mutations in viruses — including the coronavirus causing the COVID-19 pandemic — are neither new nor unexpected. Bollinger explains: “All RNA viruses mutate over time, some more than others. For example, flu viruses change often, which is why doctors recommend that you get a new flu vaccine every year."

What is the delta variant?

Since the beginning of the COVID-19 pandemic, the SARS-CoV-2 coronavirus that causes COVID-19 has mutated (changed), resulting in different variants of the virus. One of these is called the delta variant (arising from Pango lineage B.1.617.2). The delta coronavirus is considered a “variant of concern” by the WHO and CDC because it appears to be more easily transmitted from one person to another. As of September 2021, delta is regarded as the most contagious form of the SARS-CoV-2 coronavirus so far.

Here is what you should know:

The CDC recommends that everyone wait until they are fully vaccinated for COVID-19 before traveling internationally. Traveling internationally if you are not fully vaccinated for COVID-19 is not recommended, because it puts you at risk for coronavirus infection, including the SARS-CoV-2 delta variant. This includes unvaccinated children.

  • Delta rapidly became the dominant variant of the SARS-CoV-2 virus in the U.S. in 2021.
  • Delta variant SARS-CoV-2, the virus that causes COVID-19, is now in most countries where SARS-CoV-2 is circulating, and people traveling internationally are likely to encounter it.
  • Unvaccinated adults and children should strictly follow mask, distancing and hygiene safety precautions and avoid international travel if possible.
  • Being fully vaccinated for COVID-19 can protect you from the delta variant, but breakthrough infections sometimes occur.
    • All three of the F.D.A.-authorized COVID-19 vaccines can protect you from the delta variant. For Pfizer and Moderna vaccines, you need both doses for maximum protection. People should know that vaccines are very effective at preventing the most severe forms of COVID-19, but breakthrough infections can occur and caution is still warranted after becoming vaccinated.
    • While the authorized COVID-19 vaccines are not perfect, they are highly effective against serious coronavirus disease and reduce the risk of hospitalization and death.
    • Other vaccines available in other countries may not be as effective in protecting you from the delta variant and other mutations of the coronavirus.
  • Although vaccines afford very high protection, infection with the delta and other variants remain possible. Fortunately, vaccination, even among those who acquire infections, appears to prevent serious illness, hospitalization and death from COVID-19.

How many strains of COVID are there?

“We are seeing multiple variants of the SARS-CoV-2 coronavirus that are different from the version first detected in China,” Ray says.

“Different variants have emerged in England, Brazil, California and other areas. More infectious variants such as beta, delta and omicron may have increased ability to re-infect people who have recovered from earlier versions of the coronavirus, and also be somewhat resistant to some of the coronavirus vaccines. Still, vaccines currently used appear to offer significant protection from severe disease caused by coronavirus variants.”

What is a variant of concern?

Coronavirus variants are classified in different categories by organizations such as the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).

A variant of interest is a coronavirus variant that, compared to earlier forms of the virus, has genetic characteristics that predict greater transmissibility, evasion of immunity or diagnostic testing or more severe disease.

A variant of concern has been observed to be more infectious, more likely to cause breakthrough or re-infections in those who are vaccinated or previously infected. These variants are more likely to cause severe disease, evade diagnostic tests, or resist antiviral treatment. Alpha, beta, gamma, and delta variants of the SARS-CoV-2 coronavirus are classified as variants of concern.

A variant of high consequence is a variant for which current vaccines do not offer protection. As of now, there are no SARS-CoV-2 variants of high consequence.

Will the COVID-19 vaccines work on the new variants?

Ray says, “There is evidence from laboratory studies that some immune responses driven by current vaccines could be less effective against some of these variants. Those eligible for COVID-19 booster should obtain them for added protection against infection and severe disease.

“The immune response involves many components, including B cells that make antibodies and T cells that can react to infected cells, and a reduction in one does not mean that the vaccines will not offer protection.

“People who have received the vaccines should watch for changes in guidance from the CDC [Centers for Disease Control and Prevention], and continue with coronavirus safety precautions to reduce the risk of infection, such as mask wearing, physical distancing and hand hygiene.”

“We deal with mutations every year for flu virus, and will keep an eye on this coronavirus and track it,” says Bollinger. “If there would ever be a major mutation, the vaccine development process can accommodate changes, if necessary,” he explains.

How are the new coronavirus variants different?

“There’s evidence that some genetic changes in SARS-CoV-2 can result in a more contagious variant,” Bollinger says. “This is particularly true for the delta and omicron variants.”

He notes that some of the mutations seem to affect the coronavirus’s spike protein, which covers the outer coating of SARS-CoV-2 and give the virus its characteristic spiny appearance. These proteins help the virus attach to human cells in the nose, lungs and other areas of the body.

“Researchers have preliminary evidence that some of the new variants seem to bind more tightly to our cells” Bollinger says. “This appears to make some of these new strains ‘stickier’ due to changes in the spike protein and therefore more easily transmitted.”

Are coronavirus variants more dangerous?

Bollinger says that some of these mutations may enable the coronavirus to spread faster from person to person, and more infections can overwhelm healthcare facilities and result in more people getting very sick or dying. In addition, studies are underway to determine whether some variants could be associated with more severe disease.

“Therefore, it is very important for us to expand the number of genetic sequencing studies to keep track of these variants,” he says.

Bollinger explains that it may be more advantageous for a respiratory virus to evolve so that it spreads more easily. On the other hand, mutations that make a virus more deadly may not give the virus an opportunity to spread efficiently. “If we get too sick or die quickly from a particular virus, the virus has less opportunity to infect others. However, as we have seen with delta and omicron, more infections from a faster-spreading variant will lead to more hospitalizations and deaths,” he notes.

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Could a new COVID-19 variant affect children more frequently than earlier strains?

Ray says that widespread infection with the delta and omicron variants has resulted in an increased number of cases in children, including uncommon severe infections and deaths.

“There is no convincing evidence that any of the variants have special propensity to infect or cause disease in children. We need to be vigilant in monitoring such shifts, but we can only speculate at this point,” he says.

Will there be more new coronavirus variants?

Yes. As long as the coronavirus spreads through the population, mutations will continue to happen, and the delta and omicron variant families continue to evolve.

“New variants of the SARS-CoV-2 virus are detected every week,” Ray says. “Most come and go — some persist but don’t become more common; some increase in the population for a while, and then fizzle out. When a change in the infection pattern first pops up, it can be very hard to tell what’s driving the trend — changes to the virus, or changes in human behavior. It is worrisome that similar changes to the spike protein are arising independently on multiple continents.”

Are there additional COVID-19 precautions for the new coronavirus variants?

Bollinger says that as of now, none of the new coronavirus variants call for any new prevention strategies. “We need to continue doing the basic precautions that we know work to interrupt spread of the virus,” he says.

Ray concurs: “There is no demonstration yet that these variants are biologically different in ways that would require any change in current recommendations meant to limit spread of COVID-19,” he says. “Nonetheless, we must continue to be vigilant for such phenomena. For now, the greater infectiousness we’re seeing means we must redouble our efforts using the preventative tools that we have in a multi-layered approach.”

Ray stresses that both vaccination and human behavior are important. “It is striking to note that the majority of COVID-19 deaths are now occurring in unvaccinated people, even when most adults in the USA have been vaccinated,” he says.

“The more people who are unvaccinated and infected, the more chances there are for mutations to occur. Limiting the spread of the virus through maintaining COVID-19 safeguards (mask wearing, physical distancing, practicing hand hygiene and getting vaccinated) gives the virus fewer chances to change. It also reduces the spread of more infectious variants, if they do occur.

“Vaccines are the medical miracle of 2020, but we need to re-emphasize basic public health measures, including masking, physical distancing, good ventilation indoors and limiting gatherings of people in close proximity with poor ventilation. We give the virus an advantage to evolve when we congregate in more confined spaces,” he says.

Regarding coronavirus variants, how concerned should we be?

“Most of the genetic changes we see in this virus are like the scars people accumulate over a lifetime — incidental marks of the road, most of which have no great significance or functional role,” Ray says. “When the evidence is strong enough that a viral genetic change is causing a change in the behavior of the virus, we gain new insight regarding how this virus works. The virus seems to have some limitations in its evolution – the advantageous mutations are drawn from a relatively limited menu – so there is some hope that we might not see variants that fully escape our vaccines.

“Updated versions of the current vaccines are being evaluated, but there is no clinical trial evidence yet that variant-specific vaccines would provide significantly greater protection. Though SARS-CoV-2 is changing gradually, it’s still much less genetically diverse than influenza.”

“As far as these variants are concerned, we don’t need to overreact,” Bollinger says. “But, as with any virus, changes are something to be watched, to ensure that testing, treatment and vaccines are still effective. The scientists will continue to examine new versions of this coronavirus’s genetic sequencing as it evolves."

“In the meantime, we need to continue all of our efforts to prevent viral transmission and to vaccinate as many people as possible, and as soon as we can.”

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Updated January 14, 2022