This week the World Health Organization named a new “variant of interest” of the coronavirus, called the Mu variant. It was first found in Colombia in January 2021, and has been found in about 39 countries so far.
Mu has changes, called mutations, which mean it might be able to evade some of the protection we get from COVID vaccines.
But one reassuring element is that, despite being around since January 2021, it doesn’t seem to be outcompeting Delta, the dominant variant across most of the world.
If Mu was truly a really bad variant, we would have expected to have started to see indications of this, and we haven’t yet.
What’s a variant of interest?
An impressive element of our COVID response has been frequent genomic sequencing, which we haven’t done before on this scale. This tracks and maps the evolution of the virus in real time, as it adapts and mutates.
Some mutations will be detrimental to the virus, but some will be beneficial, allowing it to spread better, escape the protection offered by vaccines or even evade COVID tests.
If there are changes to the virus that mean it looks like it has the potential to do more harm, then we might designate it a “variant of interest”.
Mu has mutations that might confer some of these properties, but evidence is still emerging.
The four other variants of interest are Eta, Iota, Kappa and Lambda.
If there’s good evidence Mu is more serious and beginning to overtake other variants such as Delta, it might be upgraded to a “variant of concern”. The four variants of concern are Alpha, Beta, Gamma and Delta.
Can it escape vaccines?
Most COVID vaccines target the “spike protein” of the virus, which it uses to enter our cells. Our vaccines expose our bodies to a part of the virus, commonly the spike protein, so our immune system can learn to fight the virus off if it encounters it.
If a variant has significant changes in the spike protein, this may decrease the effectiveness of our vaccines.
The WHO said preliminary evidence suggests the Mu variant could partially evade the antibodies we get from vaccination.
But because this data is from lab studies, we can’t be sure how the variant will actually play out in the population.
We need more research to be certain about how it behaves in humans, and work on this is ongoing.
The good news is our vaccines currently protect well against symptomatic infection and severe disease from all variants of the virus so far.