Last week the World Health Organization gave its name to a new “variant of interest” of the coronavirus, the mu variant. It was first detected in Colombia in 2021 and has been reported in around 39 countries so far. Mu has changes, or mutations, that could make it able to partially circumvent the protection we have gained from covid vaccines. A reassuring element, however, is that, despite having been in circulation since January 2021, it does not seem able to outclass the delta, the dominant variant in much of the world. If mu had been a bad variant, we should have seen signs of it already, but that hasn’t happened yet.
What is a variant of interest?
A notable element of our response to covid has been frequent genomic sequencing, which has never before been done on such a large scale. This allowed us to trace and map the evolution of the virus in real time, following its adaptations and mutations.
Some mutations can be harmful to the virus, but others can be beneficial, allowing it to spread better and escape the protection offered by vaccines or the sensitivity of tampons. If there are changes in the virus that highlight the potential to cause more damage, the variant can be defined as “of interest” and be kept under observation.
The mu variant has mutations that could give the virus some of these properties, but evidence is still being gathered. The other four variants of interest are eta, iota, kappa and lambda.
If there is sufficient evidence that mu is more dangerous and is starting to overtake other variants such as delta, it could be promoted to the rank of “variant of concern”. So far the four variants of concern are alpha, beta, gamma and delta.
Can you escape vaccines?
Most covid-19 vaccines target the virus’s spike protein, which the virus uses to enter cells. Vaccines expose our bodies to part of the virus, usually the spike protein, so our immune systems can learn how to defeat the virus should it encounter it.
If a variant has significant changes in the spike protein, this could weaken the effectiveness of the vaccines.
WHO said early evidence suggests that the mu variant may partially evade the antibodies we get from the vaccine. However, since this data comes from laboratory studies, we don’t know exactly how the variant will actually behave in the population.
More research is needed to know for sure how it will behave among people, and studies on this are still ongoing. The good news is that our vaccines currently protect us well against symptomatic infection and serious illness caused by all variants of the virus identified to date.
Vaccines may not protect forever
There is a high probability that one day a new variant will emerge that can significantly escape the protection offered by vaccines, based on the original strain of the virus. We would define such a variant at risk of “immune leak”.
It is difficult to know if and when this will happen, but the uncontrolled circulation of the virus in the community increases the likelihood that a variant of this type will emerge. However, major producers of covid-19 vaccines are prepared for this eventuality. Some are already developing vaccines for new variants such as delta.
If a variant at risk of immune leak is discovered, some vaccine manufacturers could modify their vaccines to match the new variant, likely within six to eight weeks. To do this, medical regulatory authorities around the world would need to speed up the approval process. Research would be needed, but it could be conducted quickly as long as the new vaccine has the same properties as the existing ones.
At some point it could happen that a variant outclasses the delta in terms of contagiousness. Scientists believe that delta is at least 50 percent more contagious than alpha, which is about 50 percent more contagious than the original strain.
According to evolutionary theory, the virus could become more contagious but less severe over time, as the purpose of a virus is to spread as much as possible and not kill the host before it can. However, sars-cov-2 does not necessarily behave this way and at the moment we are realistically in the early stages of this virus’s life.
The best way to combat the variants is to vaccinate as many people as possible so that the virus has fewer hosts available to reproduce and mutate.
There is a risk that once the majority of the world‘s population is vaccinated, vaccines could exert “selective pressure” on the virus and cause it to evolve in such a way that it escapes vaccines. But the benefits of having more people vaccinated outweigh this risk.
I don’t think it’s time to worry about the mu variant yet. If it were to become a “variant of worry”, at that point we might get a little more worried. However, we have extraordinary tools to combat sars-cov-2, including many effective vaccines, most of which can be quickly adapted to new variants.
It is likely that in the future we will make periodic recalls to protect ourselves against variants.
(Translation by Giusy Muzzopappa)
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