Even as cases of the COVID-19 delta variant continue to spike the world over, a new variant, Mu, has become a variant of interest for the WHO. This new strain appears to have mutations with the potential to evade immunity provided by a previous COVID-19 infection or vaccination. Could Mu be a variant of concern? SUPRIYA RAMESH speaks with experts to tell you more

Since the COVID-19 pandemic hit the globe last year, there has been no let up — either in the number of cases globally nor in the emergence of new variants. When the second wave hit India, there was talk of how the third wave would affect the children more. But now, it appears that there are more worries ahead. A new varient — Mu — that had been detected in Colombia, South America is the new worry — not just for India but for the entire world.

The good part is that the Government has said that the variant has not been found in India yet, there is no telling when it may enter the country and wreak havoc.

The country reported its first COVID-19 case in Kerala on January 27, 2020, and the country has been cuffed by the virus ever since and coming out of this pandemic dungeon looks only like a distant dream. Since the World Health Organisation (WHO) declared the Delta variant as the Variant of Concern (VOC) on May 6, 2021, the country has seen a new wave of cases and death worldwide, slowing down the nation's recovery, threatening economic stability and severe social and political impacts.

The new variantis getting more attention now as it has started to spread around parts of the country and it is something to make a note of. Mu is not only being seen in high numbers or high percentages but it is being detected in different places throughout the US with highest prevalence of the variant in Colombia currently.

 It carries a cluster of mutations in the genome of COVID in the genetic structure. According to the WHO, it is still a Variant of Interest (VOI) and no samples have been detected in India yet.

"From Colombia it has spread to other South American countries such as Ecuador (13%) and Chile (around 40%). The Mu variant has now been detected in 43 countries including the United States, United Kingdom, South Korea, Japan, Ecuador, Canada and parts of Europe. So far, it has not been detected in India," says Dr Rahul Pandit, Member, COVID-19 Task Force, Maharashtra Government.

He further adds that there are more than 4700 cases of the Mu variant worldwide. Although with 2000 cases, the US has recorded the highest number of Mu cases, it is not yet regarded as an immediate threat.

"A VOI becomes a VOC when we see documented evidence that there is an increase in transmissibility of the virus, it is more dangerous, have more resistance to vaccines, and higher infectivity rate," says Dr Ankita Baidya, Consultant, Infectious Diseases, Manipal Hospital, Dwarka, New Delhi.

Despite making its first presence in January 2021, and being around since, the Mu variant doesn't seem to be as bad as Delta, which is the dominant variant across most of the world. But Mu has mutations which possess the potential of evading the protection we get from the COVID vaccines.

However, the concern is that it can lead to immune escape phenomena in the form that the existing antibodies through natural infection might not be able to protect us from this infection. "When we see such novel strains circulating in the world, it becomes a concern especially with so many mutations in it that can evade our immunity and can also reinfect a person who has already recovered from the virus from some different strain," Baidya tells you.

The WHO has said, "The Mu variant has a constellation of mutations that indicate potential properties of immune escape. Preliminary evidence shows that these mutations may allow it to escape vaccine- and convalescent serum-induced antibodies, similar to the Beta variant."

Dr Shomeshwar Singh, Lead Consultant, ENT, Madhukar Rainbow Children's Hospital says that though the reports have suggested its decline in most of the world apart from South America lately, we have to watch carefully how this strain spreads.

The exact infection rate as of now is not well established and requires more data because there have only been sporadic cases. "With the mutation that it is carrying, there are chances of having a more severe infection from this strain as it is showing some sort of immune escape phenomena, which means that the previous antibody is not working and it can result in higher infectivity rate," says Baidya.

Talking about the efficacy of vaccines, there is still a lot of research to be done in order to confirm whether the existing vaccines will be effective against the Mu strain or not. Simultaneously, the risk that it can lower the vaccine's effect is also present.

Baidya says that the signs and symptoms of the mu strain are very much similar to the Delta variant. It also has a good amount of gastrointestinal symptoms along with the normal viral symptoms of upper respiratory tract that is the cough and cold, mild fever, loose motions, abdominal symptoms, nausea and dyspepsia. There can also be some headache, leg pain and body pain as with the other viral symptoms.

Currently, only symptomatic treatment is given for any variant, similar to that of existing strains. The treatment is mostly designed according to the severity of the disease whether it is mild, moderate or severe.

Many of us are wondering how quickly the virus mutates and with every new variant emerging, recovering from this deadly pandemic seems difficult and looks like a far-fetched dream. On the other hand, we are learning to live with the pandemic and now consider it as a part of life. The virus will continue to undergo mutation in the genetic structure to evade the immune response, to evade the antibody pressure and to evade the antiviral pressure. The new mutations may be less or more severe than the existing strains but at the same time we should not stop from taking adequate infection control precautions like wearing a mask, practising hand hygiene and maintaining social distancing. "Today, the world is a smaller place since people travel far and wide in a matter of hours, this helps the virus spread. We need to exercise carefully drawn up social isolation and quarantine measures to fight the virus spread. Vaccination is very important," Singh tells you.

The Mu variant has severe mutations such as T95I, Y144S, Y145N, R346K, E484K, N501Y, D614G, P681H, Y144T, K417N and D950N in the spike protein. Some of these mutations have been detected in the variants of concern. The N501Y and  P681H mutations are also present in the Alpha variant (B.1.1.7, first detected in the UK) and have been linked to rapid transmission. The N501Y mutation is also present in the Beta and Gamma variants of concern (VOC). The E484K and K417N mutations, which also occur in the Beta variant (B.1.351, first detected in South Africa) are associated with immune escape. However, the significance of other mutations is not yet known.

• A report from England’s public health agency last month suggested the mu variant might be as resistant to vaccines as the worrisome beta variant first seen in South Africa, but said more real-world data was needed
• WHO officials said the mu variant appears to be rising in some countries in South America, but that the delta variant still spreads far more easily
• The mu variant doesn’t seem to be spreading quickly: It accounts for fewer than 1% of COVID-19 cases globally
• In Colombia, it may be responsible for about 39% of cases
• Scientists monitor emerging COVID-19 variants based on suspicious genetic changes and then look for evidence to determine whether the new version is more infectious or causes more severe illness
• Viruses evolve constantly and many new variants often fade away

‘To prevent new variants, get swiftly vaccinated’

The World Health Orgaization (WHO) has added a fifth variant of interest  (VOI)— B.1.621.1 and labelled it  — Mu variant — on August 30, 2021. The other four present VOIs are Eta (B.1.525), Iota (B.1.526), Kappa (B.1.617.1) and Lambda (C.37).

The Mu variant was first identified in Colombia in South America in January 2021, where Mu has been detected in 39 per cent of the samples analysed. From there, it has spread to other South American countries such as Ecuador (13per cent) and Chile (around 40 per cent).

The Mu variant has now been detected in 43 countries including the US, the UK, South Korea, Japan, Ecuador, Canada and parts of Europe. So far, it has not been detected in India.

According to Dr Dr Rahul Pandit, Member, COVID-19 Task Force, Maharashtra Government there are more than 4,700 cases of the Mu variant worldwide. Although with 2000 cases, the US has recorded the highest number of Mu cases, it is not yet regarded as an immediate threat.

Last month, the WHO has said that the Mu variant has a constellation of mutations that indicate potential properties of immune escape. “Preliminary evidence shows that these mutations may allow it to escape vaccine- and convalescent serum-induced antibodies, similar to the Beta variant,” Dr Pandit says.

The Mu variant has severe mutations like as T95I, Y144S, Y145N, R346K, E484K, N501Y, D614G, P681H, Y144T, K417N and D950N in the spike protein.

“Some of these mutations have been detected in the variants of concern. The N501Y and  P681H mutations are also present in the Alpha variant (B.1.1.7, first detected in the UK) and have been linked to rapid transmission. The N501Y mutation is also present in the Beta and Gamma variants of concern (VOC). The E484K and K417N mutations, which also occur in the Beta variant (B.1.351, first detected in South Africa) are associated with immune escape. However, the significance of other mutations is not yet known,” Dr Pandit tells you

The Delta variant (B.1.617.2) continues to be the predominant variant across the world and the major cause of resurgence of cases in many parts of the world.

At present, the Mu variant accounts for only 0.1 per cent of cases globally, even though it has been around since January this year.

Although it is not a variant of concern (VOC) yet, it is being closely monitored to detect any changes that would make it more transmissible than the delta variant, cause more severe disease and make vaccines less effective. If this happens, it may be re-categorised as a VOC.

“The best strategy to prevent emergence of new variants is to swiftly vaccinate as many people as possible. The larger the vaccinated population, the less the vulnerable population for the virus to infect and mutate,” Dr Pandit says.