COVID-19 may have faded from news headlines, but it hasn’t gone away — or stopped evolving. The World Health Organization now lists six ‘variants under monitoring,’ which means they need prioritized attention and tracking. One of them is NB.1.8.1, unofficially nicknamed Nimbus by the community of virus spotters who have proposed previous monikers like Kraken and Centaurus for other variants that have raised concern.
A variant is a change in the virus that can alter how it infects people, causes symptoms and spreads. Scientists around the world are constantly watching for these changes, which are called mutations. Those changes can make it easier for the virus to spread between people. They can also cause vaccines and medicines used to prevent or treat the virus to stop working.
The most common variant causing outbreaks in the United States is omicron, which has several major offshoots, or sublineages. Omicron spreads more easily than delta, but seems to cause less severe disease.
Omicron has a series of mutations that make it more infectious, including increasing its affinity for the human ACE-2 receptor. It’s also evolved the ability to escape the immune system.
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