What’s the concern about the new COVID- 19 variants? Are they more contagious?
Viruses constantly change through mutation. When a virus has one or more new mutations it’s called a variant of the original virus. Currently, several variants of the virus (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) are creating concern in the U.S. These variants include:
- Delta (B.1.617.2). This variant is now the most common COVID-19 variants in the U.S. It’s nearly twice as contagious as earlier variants and might cause more severe illness. The greatest risk of transmission is among unvaccinated people. But fully vaccinated people with breakthrough infections accompanied by symptoms can also spread the illness to others. This variant also might reduce the effectiveness of some monoclonal antibody treatments and the antibodies generated by a COVID-19 vaccine.
- Alpha. (B.1.1.7). This COVID-19 variant appears to spread more easily, with about a 50% increase in transmission compared to previous circulating variants. This variant also might have an increased risk of hospitalization and death.
- Gamma (P.1). This variant reduces the effectiveness of some monoclonal antibody medications and the antibodies generated by a previous COVID-19 infection or a COVID-19 vaccine.
- Beta (B.1.351). This variant appears to spread more easily, with about a 50% increase in transmission compared to previous circulating variants. It also reduces the effectiveness of some monoclonal antibody medications and the antibodies generated by a previous COVID-19 infection or COVID-19 vaccine.
While research suggests that COVID-19 vaccines are slightly less effective against the variants, the vaccines still appear to provide protection against severe COVID-19. For example:
- Early research from the U.K. suggests that, after full vaccination, the Pfizer-BioNTech COVID-19 vaccine is 88% effective at preventing symptomatic COVID-19 variants caused by the delta variant. The vaccine is 96% effective at preventing severe disease with the COVID-19 virus caused by the delta variant. The research also showed that the vaccine is 93% effective at preventing symptomatic COVID-19 virus caused by the alpha variant.
- Early research from Canada suggests that, after one dose, the Moderna COVID-19 vaccine is 72% effective at preventing symptomatic COVID-19 virus caused by the delta variant. One dose of the vaccine is also 96% effective at preventing severe disease with the COVID-19 virus caused by the delta variant.
- The Janssen/Johnson & Johnson COVID-19 vaccine is 85% effective at preventing severe disease with the COVID-19 virus caused by the delta variant, according to data released by Johnson & Johnson.
Currently, the CDC and the FDA state that people in the U.S. who have been fully vaccinated don’t need a vaccine booster. This is because fully vaccinated people are protected from severe disease and death with the COVID-19 virus, including from COVID-19 variants. Most COVID-19 hospitalizations and deaths are among people who are unvaccinated. However, COVID-19 vaccine manufacturers continue to research and test booster doses.
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.”
How are the new coronavirus variants different?
“There are 17 genetic changes in the alpha variant from England,” Bollinger says. “There’s some preliminary evidence that this variant is more contagious. Scientists noticed a surge of cases in areas where the new strain appeared.”
He notes that some of the mutations in the alpha version and some other variants 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, including alpha, 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. Studies are underway to understand more about whether any of the variants are more easily transmitted.”