What's the Mu Variant? And how can Malaysia enhance preparedness for more concerning variants?

KUALA LUMPUR: A coronavirus variant known as “Mu” or “B.1.621” was recently designated by the World Health Organization as a Variant of Interest (VOI). The variant was first detected in Columbia in January 2021 and since then has become the fifth VOI to be monitored by the WHO. Like Variants of Concern (VOCs), VOIs may be more contagious, able to evade the immune system, more resistant to available treatments, or harder to detect.

That said, there is less research on their impact on infections and hospitalisations compared to VOCs. Additionally, they can cause outbreaks in multiple countries but are not as widespread as VOCs. Cognisant of the above, VOIs are "of interest" to certain countries based on infection rates, which is why some VOIs are listed on the CDC's website but not the WHO's, and vice versa. But why is this particular variant a specific concern?

All viruses, including SARS-CoV-2 that causes COVID-19, mutate over time, and most mutations have little or no effect on the properties of the virus. But certain mutations can impact the properties of a virus and influence how easily it spreads, the severity of the disease it causes, and its resistance to vaccines, drugs and other countermeasures.

Mu has many mutations that suggest it could be more resistant to vaccines. The new variant detected in 39 countries possessed a 'constellation of mutations that indicate potential properties of immune escape'.

Is the Mu variant more transmissible?

Part of the concern about Mu comes from the particular mutations it carries. One genetic change, the P681H mutation, first reported in the Alpha variant and has been potentially linked to faster transmissions. However, this study is still in preprint, meaning its findings have yet to be formally reviewed by other scientists. Hence, we can't be sure of P681H's effects on the virus's behaviour just yet.

Mu also has the mutations E484K and K417N, which researchers have associated with being able to evade antibodies against the coronavirus. These mutations also occur in the beta variant, making it possible for Mu to behave like beta, which some vaccines are less effective against. Mu also has other mutations, including R346K and Y144T — their consequences remain unknown at this juncture, hence the need for further analysis.

But can Mu evade pre-existing immunity? There's only limited information on this as yet, with a study from a lab in Rome showing that the Pfizer/BioNTech vaccine was less effective against Mu compared to other variants when tested in a lab-based experiment. Despite this, the study still considered the protection offered against Mu by the vaccine to be robust.

Given that most viruses change over time, we don't yet know whether Mu's mutations will translate into increased infection and disease. In late July, a news station in Florida reported that 10 per cent of samples sequenced at the University of Miami were Mu. In early August, Reuters reported that seven fully vaccinated residents of a nursing home in Belgium had died from an outbreak of Mu.

However, these are limited snapshots of the variant's behaviour. While the variant makes up less than 0.1% of Covid infections globally, it may be gaining ground in Colombia and Ecuador where it accounts for 39% and 13% of Covid cases respectively.

Prepare now to fight the new Mu variant

Evolutionary theory predicts the virus may become more transmissible over time, therefore it’s imperative that we take heed of what is happening around us. Recent cases involving the Mu variant in both Japan and South Korea show that cases were transmitted via travellers coming from affected countries where there have been many infections involving the Mu variant (UK, US, Mexico, Colombia, etc.). With more borders reopening worldwide, it may not be long before we see this new variant in Malaysia if stringent measures are not taken soon enough.

Given the above context, The Malaysian Ministry of Health should continue taking measures to prevent the spread of the variant by closely monitoring the situation in other countries in addition to implementing strict requirements for travellers coming from countries with a Mu variant infection/circulation to take a PCR test upon arrival. And, if tested positive, to be quarantined in a designated facility or hospitalised depending on their symptoms. Even if they test negative, they should be mandated to quarantine for 14 days at home or a designated facility. PCR tests are vital as there are cases of travellers with the asymptomatic Mu variant.

Vaccination remains the ultimate shield against new variants

Every time the COVID-19 virus reproduces inside someone, there's a chance of it mutating and a new variant emerging – like rolling dice. As various studies have revealed, the main way to stop variants is through global vaccination. The emergence of Mu reminds us of how important that goal remains. With many in our country remain unvaccinated, especially those who are involved in frontline work, particularly teachers – it is imperative that we get vaccines to these people as quickly as possible to break the chain of transmissions. Otherwise, our exit from the pandemic will be set back, possibly for months on end.

Despite reduced efficacy against certain variants, vaccines still provide protection against developing severe symptoms and hospitalisations/mortality to a large extent. Cognisant of that, the government should increase our national vaccine portfolio by allowing the procurement of newer generations of COVID-19 vaccines, for example, Novavax, which has shown robust protection against the delta. The NPRA shouldn't drag its heels and delay the approval of these newer and improved generations of vaccines. Haven't we learned from our past mistakes with the slower vaccination start?

In tandem to that, the government should also look into the possibility of a booster dose for healthcare workers, especially those that were given the Pfizer-BioNTech vaccine as recent data shows immunity waning six months after receiving this particular vaccine. It is worrying if we look at the surge of infection/hospitalisation in Israel, despite being one of the first countries to vaccinate the majority of its population using Pfizer-BioNTech as their leading vaccine portfolio. Could waning immunity have contributed to the rise in cases?

In the case of the Mu variant, as explained above, it contains a recipe for disaster as an initial look at the viral genome suggests the possibility of immune evading capabilities similar to other VOCs. As scientists globally are looking in-depth at its pathogenicity, virulence and transmission, we will only get a clearer picture in the coming months. But Malaysia cannot rest its laurels and risk another variant wreaking havoc similar to what delta is doing currently. We must stay vigilant and tighten control, testing at our borders and monitor this development closely.

---

Dr. Vinod Balasubramaniam is a Molecular Virologist and Senior Lecturer at Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia.

** The views and opinions expressed in this article are those of the author(s) and do not necessarily reflect the position of Astro AWANI.