What's Mu variant? And will we keep seeing more concerning variants?

This week the World Health Organization named a new variantof interest of the coronavirus, called the Mu variant. It was first found inColombia 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 ofthe protection we get from COVID vaccines.

But one reassuring element is that, despite being aroundsince January 2021, it doesn't seem to be outcompeting Delta, the dominantvariant across most of the world. If Mu was truly a really bad variant, wewould have expected to have started to see indications of this, and we haven'tyet.



What's a variant of interest?

An impressive element of our COVID response has been frequent genomicsequencing, which we haven't done before on this scale. This tracks and mapsthe 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 evenevade COVID tests. If there are changes to the virus that mean it looks like ithas the potential to do more harm, then we might designate it a variant ofinterest .

Mu has mutations that might confer some of these properties, but evidence is stillemerging. 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 othervariants such as Delta, it might be upgraded to a variant of concern . The fourvariants 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 toenter 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 virusoff if it encounters it.

If a variant has significant changes in the spike protein, this may decreasethe effectiveness of our vaccines. The WHO said preliminary evidence suggeststhe 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 variantwill actually play out in the population. We need more research to be certainabout how it behaves in humans, and work on this is ongoing.

The good news is our vaccines currently protect well against symptomaticinfection and severe disease from all variants of the virus so far.



Vaccines may not protect forever

There's a high probability a new variant will arise one day that can significantlyescape the protection offered by our vaccines, which are based on the originalstrain of the virus. We would call this an escape variant .

It's hard to know if and when this would happen, but rampant communitytransmission of the virus increases the chances of such a variant emerging.

However, the leading COVID vaccine manufacturers are well prepared if thiseventuates. Some are already developing vaccines for new variants, such asDelta.

If we did discover an escape variant, some vaccine manufacturers could altertheir existing vaccines to match the new variant, possibly within 6-8 weeks.Medical regulators around the world would likely accelerate the approvalprocess to make this possible. Certain studies would be required but thesecould be done quickly, so long as the new vaccine had basically the sameproperties as the existing vaccine.

It's possible we could see a variant overtake Delta in terms of infectiousnesseventually. Scientists think it's at least 50% more infectious than the Alpha variant,which was about 50% more infectious than the original strain. Evolutionarytheory predicts the virus may become more transmissible over time, but lesssevere, as a virus wants to spread as much as possible and doesn't want to killits host before it can do so. But this may not necessarily be how SARS-CoV-2plays out, and realistically we're still in the early days of this virus.

The best way of combating variants is to get as many people vaccinated aspossible, so there are fewer susceptible hosts for the virus to reproduce andmutate. There is a risk that once we have the majority of the world vaccinated,vaccines may place selective pressure on the virus to evolve to escapevaccines. But the benefits of having more people vaccinated outweighs thisrisk.

I don't think it's time to be concerned about Mu yet. If it became a variant ofconcern , then we might be more worried. But we have some amazing tools tofight this virus, including many successful vaccines the majority of which canbe adapted quickly to new variants.

It's likely we'll have regular booster shots to protect us against variants inthe future.