SARS-CoV-2, the virus that causes COVID-19, has mutated into many new forms since the pandemic began. Some are more transmissible than the original virus, or more likely to reinfect people who recovered from it, but health officials don’t treat all variants as serious threats unless they meet certain criteria.
VARIANT OF INTEREST
- Definition: To the World Health Organization, a variant of interest, or VOI, is simply a form of the virus that’s shown to have different physical properties than classic SARS-CoV-2, or have new genes that could make it so. The shape of viruses, in particular the protein spikes they use to bind to host cells, is important because a variant with different spikes could be better able to infect cells or resist antibodies. But until researchers can prove that a given variant does those things, it remains a VOI. When national health agencies find a new one, they have to share its gene sequence and case details with their local WHO office. The WHO then gives it a Greek letter designation.
- Examples: Iota is a variant that emerged in New York in the fall of 2020. It showed some resistance to the antibody drugs used to treat severe COVID-19 cases, but WHO guidance says it’s unclear what clinical effect that really has.
VARIANT OF CONCERN
- Definition: VOCs are types of VOI that have been confirmed as more transmissible or more resistant to existing public-health measures. The vaccines we have now, for instance, are still mostly effective against all forms of COVID-19, but non-medical masks and physical distancing can be less effective because, if the virus is more contagious, it would take a smaller amount of virus-carrying water droplets in the air to spread it from person to person.
- Examples: The WHO’s list of VOCs so far includes the variants first identified in Britain (Alpha), South Africa (Beta), Brazil (Gamma), India (Delta), California (Epsilon) and Peru (Lambda). All have had documented cases in Canada, though Alpha is by far the most common type.
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