Scientists have raised concerns about a new variant of Covid that is spreading rapidly in the US and is threatening to cause further waves of infection.
How is it known?
It is known as XBB.1.5 and is one of the last descendants of Omicron, the transmissible version of Covid that caused a spike in cases last winter. Omicron subtypes have dominated global Covid infections ever since. The XBB.1.5 evolved from Omicron's XBB variant and is itself a fusion of two different BA.2 variants.
How fast is it spreading?
The variant appears to have spread to New York in late October. In late December, the number of cases in the US doubled in one week. Now, this new variant accounts for 40% of all Covid infections in the US. The fact that the number of hospitalizations has increased has raised fears that XBB.1.5 could cause further waves of the disease.
Why is it spreading so fast?
The variant has an unusual mutation known as F486P that is helping it spread. The mutation changes a part of the Covid virus that many antibodies target from previous vaccination or infection. The change makes the antibodies less effective at neutralizing the virus.
Does it cause more severe symptoms?
There is no evidence that XBB.1.5 causes more severe disease than other Omicron variants. But the fact that it's spreading so quickly is worrying, as the virus is more likely to infect people at risk of being hospitalized or dying from the infection, especially if they haven't been vaccinated or had a booster dose.
What do scientists advise?
Vaccines remain the best way to protect against Covid, but precautions also help, such as reducing contact, wearing masks in closed spaces and isolating if you have symptoms.
