The highly contagious Omicron variant of COVID-19 is now the fast-spreading strain of the SARS-CoV-2 virus, accounting for the maximum number of cases globally. First detected in the samples of South Africa in November 2021, this is one of the most mutated versions of the COVID virus so far. The reason behind the fast-spreading feature of the variant lies in the 32 worrisome mutations that are present in its spike protein. These mutations are enabling the Omicron variant to infect fully vaccinated individuals, which is why there is a surge in cases across the countries.
According to the latest data, Omicron has successfully replaced the Delta variant of COVID-19, in many countries, including India, the UK, and the US. Following a fresh spike in the cases, the Tamil Nadu government on Tuesday stated that the Omicron variant has completely replaced the Delta variant in the state. Urging people to not panic and follow the protocols for their own safety against the virus, Health Secretary J Radhakrishnan said, “No need to panic, but all Collectors should stay alert”.
However, there is another mutated version of Omicron (BA.1) which is the reason behind the sudden spike in cases – BA.2 or the ‘Stealth Omicron’. Let’s learn more about this variant and whether this can lead to a future surge in India as well.
BA.2 or Stealth Omicron – All You Need To Know
The BA.2 or the Stealth Omicron is not a new variant of COVID-19, it is a subvariant of the Omicron strain. The omicron variant, officially known as B.1.1.529, of SARS-CoV-2, has three main subvariants in its lineage: BA.1, BA.2, and BA.3. Earlier this month, the World Health Organization (WHO) had confirmed that the Omicron subvariant BA.2 is now the dominant strain of the virus worldwide.
What makes this variant such a big concern for scientists and public health officials? The first omicron subvariant, BA.1, is unique in the number of alterations it has compared to the original version of the virus studies have confirmed that the BA.1 Omicron variant has over 30 mutations in the spike protein that helps it enter cells. Even the newly found BA.2 or Stealth Omicron has a similar set of mutations, but it also has another extra set of eight unique mutations which are not seen in the BA.1 variant. The BA.2 also lacks 13 mutations that BA.1 does have.
Why mutations in the spike protein are concerning? it is so because they affect how infectious a particular variant is and whether it is able to escape the protective antibodies that the body produces after vaccination or prior to COVID-19 infection.
Can India Too Face Another Surge In Upcoming Months?
The HealthSite.com spoke to Dr. Viswesvaran Balasubramanian, Consultant Interventional Pulmonology and Sleep Medicine, Yashoda Hospitals Hyderabad, to understand what this recent surge in other countries mean to India, and whether we are heading towards another surge.
“Omicron sub-variant BA.2 which is also known as the stealth variant is capable of 1.5 times higher risk of transmission in comparison to the currently predominant sub-variant in India. It is currently observed that the number of cases is on the rise worldwide because of the stealth variant. However, the mortality rates aren’t much different from the existing Omicron variant,” Dr. Balasubramanian said.
Talking about the efficacy of the vaccines and prior infection immunity, Dr. Balasubramanian said, “Few studies have also hypothesized that prior infection with BA.1 subvariant produces cross-immunity and thereby helps in protection against BA.2 subvariant. In addition, it was also observed that the ability of stealth variants to escape vaccine immunity appears low. However, more data is needed to confirm this. Since the third COVID 19 wave in India was predominantly by omicron variant and most of the population is already affected or vaccinated, the chances of another wave of COVID 19 wave with stealth variant of Omicron appears less possible though cannot be completely ruled out. Adherence to pandemic norms and ensuring completion of vaccination against COVID 19 virus might help to mitigate the incidence and severity of stealth variant.”
However, studies have confirmed that the BA.2 variant is more contagious but less deadly than the BA.1 variant. “BA.2 is considered to be more transmissible but not more virulent than BA.1. This means that while BA.2 can spread faster than BA.1, it might not make people sicker,” says Dr. Pratham Mukherjee, Belle Vue Hospitals, Kolkata. He further added, “It is worth noting that while BA.1 has dominated case numbers around the world, it causes less severe disease compared to the delta variant. Recent studies from the U.K. and Denmark suggest that BA.2 may pose a similar risk of hospitalization as BA.1.”
While re-infection risks are high when it comes to new COVID-19 variants, experts have stated that people previously infected with the original BA.1 Omicron subvariant have robust protection against the BA.2 Omicron subvariant. However, this natural immunity wanes with time and thus vaccines and booster doses are important when it comes to safety measures. According to a recent study, vaccines are 80% effective at preventing hospitalization or death, and this effect increased to over 90% after a booster dose.
BA.2 Driving New Surge In Countries
BA.2 is currently driving a new wave of infection in many countries, from China to the US, people are under lockdown, with strict restrictions to curb the spread of this deadly virus variant. According to the World Health Organisation (WHO), Omicron subvariant BA.2 is the most dominant strain of COVID-19 in Southeast Asia, followed by the Eastern Mediterranean, African, Western Pacific, and European regions.
Why there is a sudden surge in cases? Experts say that the rise in BA.2 in certain parts of the world is most likely due to a combination of its higher transmissibility, people’s waning immunity, and relaxation of COVID-19 restrictions. According to the latest report, the BA.2 Omicron variant is making up 23% of all cases in the U.S.
In China, Shanghai has announced a partial lockdown in order to conduct mass testing, since the country registered a staggering number of asymptomatic cases associated with the BA.2 Omicron variant. China has reported more than 56,000 confirmed cases nationwide this month, with the surge in Jilin accounting for most of them.
Implications For India
Taking cognizance of the current pandemic situation in other parts of the world, India has already announced a high alert in many states (especially the worst affected ones). Earlier this week, the Maharashtra government had issued a fresh warning to keep a track of the new infection rate and proper surveillance for any new surge in the state. Experts have also asked people to maintain and follow the COVID safety protocols.
“Whether there will be another devastating surge depends on how many people are vaccinated or have been previously infected with BA.1. It’s safer to generate immunity from a vaccine, however than from getting an infection,” Immunologists Prakash Nagarkatti, the University of South Carolina, quoted as saying. Talking about ways the virus spread can be stopped, he said, “Getting vaccinated and boosted and taking precautions like wearing an N95 mask and social distancing are the best ways to protect yourself from BA.2 and other variants”.
