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Explained: What's Behind The Covid-19 Surge, What's XBB.1.16 Strain, Should You Be Worried?

Experts have said there is no need to panic and people should follow Covid-appropriate behaviour and get booster vaccine doses if they have not already.

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India reported 1,590 daily Covid-19 cases on Saturday. This has led to concerns as the rise in infections is more concentrated some pockets like the Delhi and National Capital Region (NCR). 

Active cases in India currently stand at 8,601, according to Union Ministry of Health and Family Welfare. It further reported in its daily bulletin that that a total of six people died in the past 24 hours, marking a daily rise of 1.19 per cent.

The daily infections on Saturday were almost double the number reported a week ago, according to the NDTV Covid-19 tracker, which says 843 cases were reported a week back.

Experts have said that XBB.1.16 variant could be driving the rise in cases in areas like Delhi. Earlier, the Health Ministry also took note of the rising H3N2 viral infections.

Here we explain what's XBB.1.16 Covid-19 strain, what the experts say about the current surge, what you should do about it.

How does a virus evolve?

The Covid-19 disease is caused by the SARS-CoV-2 virus, which is one of the many types of the coronaviruses present in the world.

Like any other virus, SARS-CoV-2 has evolved over time and has acquired a number of mutations over time. These mutations lead to the emergence of several variants and sub-variants. 

"Viruses are constantly evolving and changing. Every time a virus replicates (makes copies of itself), there is the potential for there to be changes in its structure. Each of these changes is a 'mutation'. A virus with one or more mutations is called a 'variant' of the original virus," says the World Health Organization (WHO) in an article. 

Variants of the virus evolve further and make sub-branches called sub-variants. Some of the well-known variants are Alpha, Delta, and Omicron. They have several sub-variants. For example, the Delta variant that led India's deadly second Covid-19 wave has up to 200 sub-variants. In common terms, any mutated form of the virus is called a strain. It can refer to both a variant and sub-variant.

While most mutations are fairly regular, some mutations make the virus more transmissible (such as Omicron) or deadlier (such as Delta). 

What we know about XBB.1.16 Covid-19 strain?

Some experts say that XBB.1.16 Covid-19 strain might be behind India's ongoing Covid-19 surge.

The XBB.1.16 variant is a recombinant —a mixture, simply speaking— strain of BA.2.10.1 and BA.2.75 sublineages, according to WHO.

The WHO notes that XBB.1.16 was first documented on January 23. It is currently designated as a variant under monitoring along with other variants.

Notably, BA.2.10.1 and BA.2.75 are both sub-variants of highly transmissible variants of Omicron. Recently, another sub-variant of Omicron named BF.7 was believed to be fuelling the deadly Covid-19 wave in China. 

What have experts said on Covid surge?

Experts have said XBB.1.16 could be fuelling the surge in Delhi. However, they also said that one should take regular Covid-16 precautions.

Dr Jugal Kishore, head of the medicine department at the Centre-run Safdarjung Hospital in Delhi, said that Covid has become "similar to influenza" where the virus undergoes change every year and infects people.

"Omicron infected more than 95 per cent of the population. People have developed antibodies against it and chances of infection from the same variant are less unless the surface antigens change. XBB.1.16, a variant of Omicron, which originated in Japan and was found in China and Singapore, could be behind the rise in cases (in India)," said Kishore.

It has a high transmissibility and cases are likely to increase, but there won't be many deaths, the doctor said, adding that an increase in testing will reflect the increase in number.

Dr Kishore, however, cautioned people with comorbidities and those who have a severe illness, saying they are at a higher risk. He feared there could be mortality in these cases.

"People who have not taken a booster vaccine dose should take it, especially those who have people with comorbidities or patients in their families," he said.

Dr Richa Sareen, a consultant in pulmonology at Fortis hospital here, said, "I feel the rise in Covid cases is led by the new variant. But XBB.1.16 is a variant of Omicron and so there shouldn't be much to worry about as most people have developed antibodies over time, especially after the last wave driven by Omicron," she said.

However, there's a need to exercise caution and people should wear masks in crowded places, she said, adding that those who are immunocompromised or have comorbidities should be extra careful.

Former AIIMS director Dr Randeep Guleria on Wednesday said the XBB.1.16 variant could be driving the recent rise but emphasised there was no need for panic as long it does not cause severe illness and deaths.

Dr Guleria said any virus evolves over time and this has happened with both Covid and influenza.

This is what is called antigenic drift, he said.

It will gradually evolve, mutate a little bit and new variants will emerge, Guleria added.

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What we know of the Covid-19 surge?

Experts have said there is no need to panic and people should follow Covid-appropriate behaviour and get booster shots if they have not already.

They also say this rise could be a result of more people getting themselves tested for Covid as a precaution when they actually get infected with the influenza virus and develop fever and related ailments.

Over the past week, Delhi has seen a rise in daily Covid cases amid a sharp increase in H3N2 influenza cases in parts of the country, including the national capital.

On Friday, Delhi recorded over 150 fresh Covid cases with a positivity rate of 6.66 per cent. A day before that, it logged 117 cases with a positivity rate of 4.95 per cent. The number of daily Covid cases has nearly doubled since Tuesday when 83 fresh Covid cases were reported with a positivity rate of 5.83 per cent and one fatality.

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The number of fresh Covid cases had dropped to zero on January 16, the first time since the pandemic began. This is the first time since October last year that Delhi recorded daily Covid-19 cases in three digits.

The Delhi health department data showed that 1,653 tests were conducted on Tuesday and 2,282 tests were done on Thursday. Only 27 of the 7,984 beds are occupied in dedicated Covid-19 hospitals, while 250 patients are in home isolation, the department said in a bulletin on Friday.

The number of active cases in the national capital currently stands at 424, the data showed. 

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Dr Jugal Kishore, head of the medicine department at the Centre-run Safdarjung Hospital in Delhi, said that Covid has become "similar to influenza" where the virus undergoes change every year and infects people.

"Omicron infected more than 95 per cent of the population. People have developed antibodies against it and chances of infection from the same variant are less unless the surface antigens change. XBB.1.16, a variant of Omicron, which originated in Japan and was found in China and Singapore, could be behind the rise in cases (in India)," he said.

A senior doctor at LNJP, Delhi government's largest hospital and the mainstay of its fight against the pandemic, said, "New variants keep coming as the virus evolves. But the current situation in Delhi seems to stem from a rise in influenza cases. As more people are falling sick, more people are getting themselves tested for Covid. So the rise in the number of cases is being seen."

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However, there's nothing to panic about at the moment and people should take all precautions, the doctor said.

"Yesterday, three Covid patients were admitted to LNJP and one more was admitted today. So four people are admitted as of now. We have a few patients of influenza too, who are admitted in a separate room," she said.

This is also flu season

Earlier this month, the Union Health Ministry also took note of the flu outbreak in the country and said India is currently experiencing its annual flu season. Cases of H3N2 flu have sparked concerns lately. However, it's not a new virus and there exist proven vaccines and treatment options for it.

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The currently prevalent H3N2 infections are part of the annual viral cycles, said Union Health Ministry in a statement on March 10.

"India every year witnesses two peaks of seasonal influenza: one from Jan to March and other in post monsoon season. The cases arising from seasonal influenza are expected to decline from March end," said the Health Ministry.

(With PTI inputs)

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