While media reports sometimes use words like “mutation,” “strain” and “variants” interchangeably, there are differences.
“Mutations are changes that are basically typos that occur in the genome of the virus as it makes copies of itself and moves from person to person,” explained Pavitra Roychoudhury, a coronavirus genetics expert and instructor in the department of laboratory medicine and pathology at the University of Washington School of Medicine.
“Variants we define as a particular version of the virus that has a specific combination of mutations across its genome,” Roychoudhury continued. “A variant becomes a variant of concern when we start to see it rising in frequency over the population, over a period of time.”
The U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) are now tracking three variants of concern (though the virus is evolving constantly and these are not the only ones): The variant first discovered in the U.K., the variant first discovered in South Africa, and the one found in Brazil.
Here’s a basic breakdown on what we know so far about how these variants compare with each other ― as well as with the original version of the coronavirus:
The original SARS-CoV-2
How long it has been circulating: In January 2020, the WHO announced a mysterious coronavirus-like pneumonia was circulating in Wuhan, China. About one month later, the WHO gave an official name to both the virus (severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2) and the disease it causes (COVID-19). Reports now suggest the virus was circulating well before officials confirmed the earliest cases — perhaps since October 2019.
What we know about it: Most of the information researchers have about COVID-19 to date is based on the original virus.
Vaccine effectiveness: The Pfizer shot is 95 per cent effective against symptomatic disease. The Moderna shot is 94.5 per cent effective.
Among the vaccines not currently available in Canada or the United States, the Novavax vaccine is 89.3 per cent effective against symptomatic disease, Johnson & Johnson’s is 66 per cent effective at preventing symptomatic disease and 85 per cent at preventing severe disease, and Oxford/AstraZeneca is 70 per cent effective against symptomatic disease.
B.1.1.7 (the U.K. variant)
How long it has been circulating: This variant was first identified in the U.K. during the fall.
Countries where there have been reported cases: B.1.1.7 has been identified in more than 80 countries to date. Canada reported its first cases in Ontario on Dec. 26, 2020. The United States had its first case confirmed four days later, and it has been detected in 42 states. Experts have predicted it will be the dominant strain in the U.S. by March.
What we know about it: This strain spreads more easily than other variants, which likely contributed to the surge in cases in the U.K. earlier this winter despite stay-at-home orders. “We know B.1.1.7 is more transmissible,” Roychoudhury said.
At first, health officials believed that B.1.1.7 was no more likely to cause severe illness or death than the original SARS-CoV-2. Now, however, they are reassessing and believe it may be more lethal than the original strain — though at this point no large-scale epidemiological studies back that hypothesis. It may appear more deadly because more infections ultimately can lead to more hospitalizations and deaths.
“There is some emerging data on whether it causes more severe disease,” Roychoudhury said. “But consensus has not been broadly reached on that.”
Vaccine effectiveness: The Pfizer and Moderna vaccines both appear to protect well against B.1.1.7 (and both companies are working on boosters to address current and future mutations).
The Novavax, Johnson & Johnson and Oxford/AstraZeneca vaccines all appear to protect against B.1.1.7 pretty well.
B.1.351 (the South Africa variant)
How long it has been circulating: The B.1.351 variant was first identified in South Africa in October.
Countries where there have been reported cases: The strain has been identified in 24 countries to date, and was first detected in Canada and the United States in January.
What we know about it: This variant shares certain mutations with the strain found in the U.K., and it appears to be 50 per cent more transmissible than earlier strains of the virus. However, there is no data at this point to suggest it is more likely to cause severe illness or death.
Experts are paying particularly close attention to B.1.351, because clinical trials suggest the vaccines that are currently available or in development may not be as effective at protecting against it as they are against other strains.
There is also some preliminary evidence that certain treatments may not work as well. “The monoclonal antibodies that we use as treatment may be less effective against this,” said Edgar Sanchez, an infectious disease expert at Orlando Health.
Vaccine effectiveness: Early data suggests the Pfizer and the Moderna vaccines may be less effective against B.1.351, but both still offer good protection. And a small but promising clinical trial found that Pfizer’s vaccine can effectively neutralize the variant.
The Novavax shot appears to be around 60 per cent effective against the variant. The Johnson & Johnson vaccine is 57 per cent effective, based on current data. There is not enough data yet on the Oxford/AstraZeneca vaccine to say. While discouraging, these levels of protection are still better than nothing.