4th September 2021 – (Hong Kong) The Department of Health announced yesterday that as of 3rd September, among the confirmed COVID-19 cases involving a mutant virus strain recorded by the Centre for Health Protection, 3 cases of the “Mu” mutant virus strain (ie B.1.621) were found, with the case numbers 11867 , 11868 and 11976. Looking through the data, two of the patients arrived in Hong Kong from Colombia on 8th June and the other entered the United States on 24th July, and had received two doses of Corminaty vaccine.
World Health Organisation recently listed the “Mu” (B.1.621) variant of the new coronavirus as a “variant of interest” together with “Eta”, “Iota”, “Kappa” and “Lambda”. The threat is lower than the first-level “variant of concern” (VOC) and the “Delta,” which is raging around the world, is the first-level VOC.
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.
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.
What we know of this new variant so far:
- The variant is scientifically known as B.1.621 and was classified as a variant of interest in August, 2021
- The WHO said its global prevalence has declined to below 0.1 percent among sequenced cases. In Colombia, however, it is at 39 percent
- The variant might have immune escape properties as it has a constellation of mutations
- The WHO’s weekly bulletin on the pandemic said the variant has mutations suggesting it could be more resistant to vaccines, as was the case with Beta, but that more studies would be needed to examine this further
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.
The good news is our vaccines currently protect well against symptomatic infection and severe disease from all variants of the virus so far.
There’s a high probability a new variant will arise one day that can significantly escape the protection offered by our vaccines, which are based on the original strain of the virus. We would call this an “escape variant”.
It’s hard to know if and when this would happen, but rampant community transmission of the virus increases the chances of such a variant emerging.
However, the leading COVID vaccine manufacturers are well prepared if this eventuates. Some are already developing vaccines for new variants, such as Delta.
If we did discover an escape variant, some vaccine manufacturers could alter their existing vaccines to match the new variant, possibly within 6-8 weeks. Medical regulators around the world would likely accelerate the approval process to make this possible. Certain studies would be required but these could be done quickly, so long as the new vaccine had basically the same properties as the existing vaccine.
It’s possible we could see a variant overtake Delta in terms of infectiousness eventually. Scientists think it’s at least 50% more infectious than the Alpha variant, which was about 50% more infectious than the original strain.
Evolutionary theory predicts the virus may become more transmissible over time, but less severe, as a virus wants to spread as much as possible and doesn’t want to kill its host before it can do so. But this may not necessarily be how SARS-CoV-2 plays 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 as possible, so there are fewer susceptible hosts for the virus to reproduce and mutate.
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 escape vaccines. But the benefits of having more people vaccinated outweighs this risk.
I don’t think it’s time to be concerned about Mu yet. If it became a “variant of concern”, then we might be more worried. But we have some amazing tools to fight this virus, including many successful vaccines — the majority of which can be adapted quickly to new variants.
It’s likely we’ll have regular booster shots to protect us against variants in the future.
Excerpt of this article appeared in The Conversation and First Post.