By Susan McBratney, PhD
The novel coronavirus, SARS-CoV-2, is an easily spread respiratory virus and the cause of the COVID-19 pandemic. As countries around the world are rolling out new COVID-19 vaccines to control the outbreak, scientists are discovering new variants of the COVID-19 virus, including the variant first identified in the United Kingdom. What makes a virus variant, how does it affect the disease, and will the vaccine protect against the U.K. and other variants? Here’s what is known so far.
1. Variants are mutations in the genetic material of the virus.
Virus mutations are normal and expected as the COVID-19 virus gets passed person to person. Another name for a mutation is a variation, so mutated viruses are variants of the original virus. (You may see the term virus “strain” used interchangeably with variant and mutant.) Some mutations help the virus, such as making it more contagious. Variant viruses with these types of mutations will usually persist or even overtake the original virus in circulation. This is happening with the new U.K. COVID-19 variant and other variants.
2. The COVID-19 variants have several mutations affecting the spike protein.
The U.K. variant is named SARS-CoV-2 VOC 202012/01, for ‘Variant of Concern, year 2020, month 12, variant 01.’ Another name for it is B.1.1.7. This virus has many mutations, some of which change or delete parts of the spike (S) protein—the protein required for the coronavirus to infect cells. This protein is the target of many COVID-19 vaccines.
Other COVID-19 variants of concern include one first discovered in South Africa (variant B.1.351) and another in Brazil (variant P.1). These variants have some of the same mutations as the U.K. variant, but the variants are distinct and arose independently. A Denmark COVID-19 variant, L452R, in traced to minks. The variant then started infecting people working at mink farms.
3. The new variants spread more easily.
The B.1.1.7 SARS-CoV-2 variant is widespread in England. It is more contagious—spreading 30 to 50% faster, by some accounts. How does that happen? Compared to the original novel coronavirus, the variant virus binds more easily to human cells, accelerating its ability to multiply and cause illness. Coronavirus scientists expect this type of behavior based on the specific changes in the variant. The South Africa and Brazil variants also appear to spread faster than the COVID-19 virus that began the pandemic. These three variants are in the United States too; the U.K. variant may become the most common U.S. COVID-19 strain.
4. The CDC is tracking COVID-19 variants.
Because viruses like SARS-CoV-2 mutate easily, more variants are likely. Most SARS-CoV-2 mutations are not significant and do not reach the status of “variant of concern.” However, some variants may out-compete the circulating virus strain and become the predominant strain. Check the CDC for more information about these and other variants.
5. Some variants may cause more severe COVID-19.
There is some evidence the U.K. variant causes more severe COVID-19. Even if COVID-19 variants do not cause more severe disease, the problem is more cases of COVID-19 translates to more people potentially needing medical care in a system that is already stretched thin from the existing rate of infection and people needing intensive care.
6. COVID-19 vaccines may be less potent against certain variants.
Researchers are optimistic about vaccine effectiveness against the variant because of how vaccines work. The spike protein would have to change drastically for the virus to evade the immune system in a vaccinated individual (or in someone with natural immunity due to previous infection), and this is not likely to happen.
Still, the South Africa variant has certain changes that may allow it to evade the immune system, which could render the vaccine less effective. Studies are underway to investigate if that is the case. Preliminary studies with the Pfizer-BioNTech and Moderna COVID-19 vaccines show that antibodies from vaccinated individuals can recognize and neutralize viruses containing a concerning South Africa mutation, at least in a test tube. Neutralization was less efficient with the mutated virus compared to the more common circulating virus, but it is high enough to be protective in a vaccinated individual exposed to a variant. To be proactive, Moderna announced they are testing a third shot of the first vaccine as a booster as well as developing a new vaccine that could be used as a booster shot to protect against disease caused by the South Africa variant.
Novavax, which has a COVID-19 vaccine in clinical trials, has early evidence the vaccine is 85% effective against the U.K. variant, but about 50% effective against the South Africa variant.
The Brazil variant is troubling because it may be able to evade the immune system (and it appears to be more contagious). More studies are underway to understand the P.1 variant from Brazil, and vaccine effectiveness against it.
7. COVID-19 reinfection with the variants is a concern.
Reinfection means infection in a person who already had COVID-19, and presumably had at least some natural immunity. There have been reports of reinfection with the variants, but doctors do not yet know the frequency of reinfection. Because the South Africa and Brazil variants appear to evade the immune system to some degree, scientists believe reinfection is more likely with these variants than with the more common circulating strain, which is rare.
COVID-19 experts monitor possible reinfection cases closely. They are also tracking COVID-19 cases in people who were vaccinated. Early studies indicate the COVID-19 vaccines offer some protection from disease caused by the variants.
8. Additional testing is necessary to identify and confirm a COVID-19 variant.
The most common diagnostic COVID-19 tests confirm an active infection, but they don’t identify the specific virus variant. If your doctor or the lab that processed your sample needs to know if it contains a variant, they perform an additional step: They analyze the sequence of the virus genetic material for mutations. Genetic analysis is not standard practice during testing. However, starting in January, the U.S. Centers for Disease Control and Prevention (CDC) is requiring each state to submit 10 patient samples biweekly to CDC labs for analysis.
9. COVID-19 treatments may need to be updated.
Antibody therapies for treating COVID-19 are available. Both therapies are monoclonal antibodies that target a specific part of the spike protein. The antibodies should still target the spike protein of the U.K. variant and reduce the risk of severe illness. However, it’s possible other strains of the COVID-19 virus may limit how well current (and new) treatments work. Drug companies are already adapting existing treatments to target new COVID-19 variants.
10. COVID-19 variants may affect rapid antigen test effectiveness.
Most rapid tests detect a SARS-CoV-2 antigen unrelated to the spike protein, so these tests would detect the new U.K. variant (with its multiple changes in the S protein) in a nasal swab of an infected person. Rapid antigen tests work well as a diagnostic tool when a person has a lot of virus in their nasal swab. But a variant that can infect people more easily and at a lower viral load—perhaps below the level of detection of an antigen test—increases the risk of a false negative result.
There has always been skepticism about using rapid antigen tests due to the risk of false negative results in infected asymptomatic people. New variants that can spread easily without a high viral load in the nose may make antigen tests an even riskier choice over molecular tests like PCR for diagnosing or ruling out COVID-19.
Leave a Reply