The coronavirus is changing forms --- one after another. While scientists are working tirelessly towards developing drugs and vaccines against the virus, the virus also kept changing its forms and challenging their efforts.

Viruses constantly change through mutation to give new variants of themselves. In the last year and a half since the emergence of the coronavirus, more than 4,000 mutations have occurred in the spike protein alone. However, most of these variants caused by mutations do not carry any special significance.

A variant only becomes important when it is found to be more infections than the original virus, causes more serious illness, spreads faster, or is able to escape immunity acquired through previous infections or vaccinations. Some of such variants of coronavirus have been found responsible for fresh surge in the pandemic in different parts of the world. So far, scientists have identified four such variants, namely the UK variant (B.1.1.7), the Brazilian variant (P.1), the South African variant (B.1.351) and the Californian variant (B.1.429). These variants are referred to as variants of concern. The latest addition to this list may be a new variant detected in neighboring India --- the Indian variant, B.1.617. However, although this variant seems to be worrisome, its status has not yet been confirmed and so it is still considered a variant of interest. The UK regulatory authority, Public Health England, have categorized it as a 'variant under investigation'. (What do we know about the Indian coronavirus variant? | Coronavirus | The Guardian, April 19, 2021)

Recently, COVID-19 pandemic has taken a very dangerous turn in India. The case numbers and death toll had started to drop in India last September, after a high of around 100,000 infections and 1,000 deaths per day, and by mid-February this year it dropped to an all-time low of about 10,000 and 100, respectively. But they began to rise again in March, and according to the latest statistics, the number of daily infections has crossed 400,000 and the number of deaths per day has exceeded 3,500.

It was like lightning without clouds. By mid-February, when the infection had reached its lowest level ever, many assumed that perhaps the worst of the epidemic had been over. Antibody studies conducted by the National Institute of Epidemiology in Chennai in December and January estimated that more than 50 per cent of the population in some areas of India's major cities and, nationally, about one-fifth of India's total population had already been exposed to the virus, which should have conferred them some immunity. These figures made some researchers optimistic that the next stage of the pandemic would be less severe, says Ramanan Laxminarayan, an epidemiologist in Princeton University, New Jersey, who is based in New Delhi. (India's massive COVID surge puzzles scientists | nature, April 21, 2021)

But the reality had been exactly opposite. The question is, why did the infection suddenly rise again with such a meteoric speed? What could be the underlying cause? Was it because people let their guards down and began to mix and move recklessly as they saw that the cases were declining, and the vaccination campaign has kicked off? Or was it due to emergence of a new, more infectious variant? It is not clear yet what actually triggered the surge. However, the new variant, B.1.617, dubbed as 'double mutant', has drawn particular attention of scientists.

What makes this variant unique is the combination of two 'infamous' mutations in its spike protein that were found separately in some of the previously identified dangerous variants, but not in any one together. That is the basis of dubbing it as 'double mutant'. This does not necessarily mean that it contains just two mutations; it has rather more than a dozen. One mutation, E484Q, is similar to the E484K mutation in the Brazilian variant, the South African variant and some strains of the UK variant. Studies suggest that this mutation reduce the effectiveness of antibodies produced by previous infections or vaccinations. The second mutation, L452R, has previously been detected in the Californian variant. This mutation increases viral transmission by around 20% and reduces antibody efficacy by more than 50%, says Dr Anurag Agrawal, the director of CSIR-IGIB, India. (Is a double mutant COVID variant behind India's record surge? Al Jazeera, April 19, 2021) So, it is clear that the presence of these two mutations together makes the virus more infectious and may let it evade antibodies produced by vaccination or previous infection. So, in theory, there is enough ground to consider it as a 'variant of concern'. "The B.1.617 variant has all the hallmarks of a very dangerous virus," William A. Haseltine, a former professor at Harvard Medical School wrote in a recent article in Forbes. (An Indian SARS-CoV-2 Variant Lands In California. More Danger Ahead? | Forbes, April 12, 2021)

The question now is whether the practical evidence suggests this variant to be responsible for the recent surge in infections in India. There is good reason to believe so, as far as the genome sequencing data published in media are concerned. According to outbreak.info, a website tracker for COVID-19, the average prevalence of the variant in India surged to as high as 52% of samples sequenced in April from almost nothing in January. (Covid-19: India Has A Double Mutant Virus Variant. Should We Be Worried? | Bloomberg | Quint, April 16, 2001) Meanwhile, the National Institute of Virology (NIV) in Pune, India reported that of 361 samples taken and sequenced in Maharashtra, the epicenter of recent outbreak, from January to March, 220, i.e., 61 per cent, had the double mutation E484Q and L452R. (Maharashtra: Double Mutation Found In 61% of 361 Covid-19 Samples | Outlook, April 14, 2021)

In addition to the results of genome sequencing, there is one more thing to note here. Dr Zarir Udwadia, a clinician-researcher at PD Hinduja Hospital and Medical Research Centre in Mumbai anecdotally observes that entire households are now getting infected - unlike in the first wave of COVID-19, when single individuals would test positive. He attributes this to the presence of more-infectious variants. Dr Udwadia was speaking to the science magazine Nature during a break from working in the intensive-care unit.

Experts, however, think it would be too early to conclude that this variant was responsible for the recent surge. One reason is that the number of samples sequenced so far was very small compared with the number of cases. "This sample size (i.e., 361 samples) is too small to conclude as Maharashtra has been conducting nearly two lakh tests per day." --- said a senior genome sequencing expert to PTI. (Double mutation found in 61% of 361 COVID-19 samples tested between Jan-March 2021: Expert- The New Indian Express, April 14, 2021) Echoing to that, Dr Gangandeep Kang, professor of microbiology at Christian Medical College, Vellore, said: 60.9 per cent samples carrying this variant "most likely" showed a link between the mutation and the surge - however, for an accurate answer at least 1 per cent of Covid-19 samples must be sequenced every week. With India at present testing over 1 lakh cases daily, this would translate to roughly 1,000 genome sequences every day. (Explained: B.1.617 variant and the Covid-19 surge in India | Explained News, The Indian Express, April 27, 2021)

On the other hand, although it seems to be more infectious, clinical anecdotes from doctors suggests that the variant is less virulent. Most patients can do with home isolation --- do not require hospitalization. "Most patients are asymptomatic and that is a good indication. But in absolute numbers so many cases have put a burden on health infrastructure," said Dr Shashank Joshi, an expert on the Maharashtra Covid Task Force. (Explained: B.1.617 variant and the Covid-19 surge in India | Explained News, The Indian Express, April 27, 2021) Further, research suggests that the Indian vaccine, Covaxin works well against this variant. (Covaxin offers protection against double mutant variant found in India: study - The Hindu, April 28, 2021) If that is true, there will be some mitigation to concerns over efficacy of vaccines against

this variant.

The variant B.1.617 was first detected in India in October. According to the World Health Organization sources, this variant has already spread to at least 17 countries across the world, including the United Kingdom and the United States. However, it has spread the most in India. (Indian coronavirus strain found in UK, US, and 15 other countries: WHO | mint, April 28, 2021). On May 8, Bangladesh reported its first cases of the Indiam variant. Considering the porous border between the two countries, it is likely to have been here much longer.

Therefore, it is necessary for Bangladesh to come up with an action plan right now. Amid devastating surge in COVID-19 infections in India and concerns over the new variant, Bangladesh like many other countries in the world imposed restrictions on the entry of travelers from India. However, it is not enough to impose such restrictions. There is a need for massive sequencing initiatives by collecting samples from different parts of the country so that the variant can be quickly identified and its spread can be controlled.

Another issue is that as many people as possible need to be vaccinated in the quickest possible time so that the infection does not spread. This is because the more the virus spreads, the more likely it is to mutate. This can lead to the emergence of new variants, against which existing vaccines may not work well.

One more thing needs special attention. The recent resurgence in COVID-19 infection in Bangladesh and India, after apparently having come down under control, showed with a finger in the eye that this deadly germ is very cunning, deceitful. After going on the backfoot for a while, it can change its form and hit back again with renewed vigor. So, there is no chance to be complacent even for a moment by looking at the statistics or thinking that I have been vaccinated. Remember, this deadly germ can attack you at the very moment of momentary carelessness. Therefore, you should always carry protective armor, such as hand washing / sanitization, wearing a mask, maintaining physical distance, and avoiding public gatherings, until you receive a convincing message that the killer has been completely eradicated. There is no chance of even minimal relaxation here.

All the best to everyone!

Dr Mohammad Didare Alam Muhsin, Professor of Pharmacy, Jahangirnagar University.