In the sudden surge of Covid cases, India recorded a single-day rise of 702 new cases on Thursday. The Ministry of Health and Family Welfare has said the active caseload in the country now totals 4,097. The Indian state of Kerala has the highest number of cases.

India Covid: New JN.1 sub-variant causes worry, India report 4,097 active cases

Even after causing havoc for last two years, coronavirus seems to have been refusing to die down. &nbsp;&nbsp;

Currently, different parts of the world have been witnessing a surge in the number of cases due to the spread of a sub-variant of the highly transmissible Omicron variant of coronavirus. &nbsp;

The sub-variant is called BA.2. It is now dominant worldwide. &nbsp;

What is the BA.2 variant? &nbsp;

Amid the surge in Omicron cases, British health officials had earlier detected growing cases of BA.2 variant. In total, Omicron has three sub-strains - BA.1, BA.2 and BA.3.&nbsp;&nbsp;

Also Read:&nbsp;<a href="https://www.wionews.com/science/different-variants-may-cause-different-long-covid-19-symptoms-says-study-466250" hreflang="en">Different variants may cause different long COVID-19 symptoms, says study</a>

As it is slightly harder to track, BA.2 is also called the "stealth variant". &nbsp;BA.1 is tracked through a common PCR test by default due to a missing gene. While BA.2 and another sibling, BA.3 can be found only by genomic sequencing. &nbsp;&nbsp;

Should you be concerned? &nbsp;

According to the World Health Organization, BA.2 now represents around 86% of all sequenced cases. It is more transmissible than other sub-variants, like BA.1 and BA.1.1. But the evidence so far suggests that it is less likely to cause severe infection. &nbsp;

Watch:&nbsp;Shanghai tightens COVID lockdown: Curbs imposed on highway traffic

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Vaccines are also less effective against BA.2. As per UK Health Security Agency data, protection gets restored by a booster jab, particularly for preventing hospitalisation and death.&nbsp;&nbsp;

BA.2 has led to surges in China and European countries like Germany and the UK. It is also raising concern over the potential for a new wave in the United States.

Can it&nbsp;re-infect people?

As a&nbsp;number of countries are experiencing "double peaks" in infection rates simultaneously,&nbsp;a key concern about BA.2 is that whether it could re-infect people who had already had BA.1.

But data from both the UK and Denmark show&nbsp;that while Omicron can reinfect people, who had other variants, like Delta, only a handful of BA.2 reinfections in people, who earlier had BA.1 have been found so far.&nbsp;

According to the&nbsp;scientists, a explanation for the recent spike in BA.2 cases could be the global uptick happened at the same time in many countries after lifting of public health interventions.

"In some ways, it could just be that BA.2 was the variant that was circulating when all these people stopped wearing masks," said Dr Andrew Pekosz, virologist, Johns Hopkins Bloomberg School of Public Health in Baltimore.

Other US&nbsp;experts, such as Eric Topol, director, Scripps Research Translational Institute in La Jolla, California, said it was "a little too early" to call whether the US&nbsp;too would see a significant BA.2 wave.

"It is still a huge public health problem and it is going to continue to be," said Mark Woolhouse, epidemiologist, the University of Edinburgh.

(With inputs from agencies)&nbsp;

Even after causing havoc for last two years, coronavirus seems to have been refusing to die down. Currently, different parts of the world have been witnessing a surge in the number of cases due to the spread of a sub-variant of the highly transmissible Omicron variant of coronavirus.

Even after causing havoc for last two years, coronavirus seems to have been refusing to die down. Currently, different parts of the world have been witnessing a surge in the number of cases due to the spread of a sub-variant of the highly transmissible Omicron variant of coronavirus. The sub-variant is called BA.2. It is now dominant worldwide. What is the BA.2 variant? Amid the surge in Omicron cases, British health officials had earlier detected growing cases of BA.2 variant. In total, Omicron has three sub-strains - BA.1, BA.2 and BA.3. Also Read: Different variants may cause different long COVID-19 symptoms, says study As it is slightly harder to track, BA.2 is also called the "stealth variant". BA.1 is tracked through a common PCR test by default due to a missing gene. While BA.2 and another sibling, BA.3 can be found only by genomic sequencing. Should you be concerned? According to the World Health Organization, BA.2 now represents around 86% of all sequenced cases. It is more transmissible than other sub-variants, like BA.1 and BA.1.1. But the evidence so far suggests that it is less likely to cause severe infection. Watch: Shanghai tightens COVID lockdown: Curbs imposed on highway traffic × Vaccines are also less effective against BA.2. As per UK Health Security Agency data, protection gets restored by a booster jab, particularly for preventing hospitalisation and death. BA.2 has led to surges in China and European countries like Germany and the UK. It is also raising concern over the potential for a new wave in the United States. Can it re-infect people? As a number of countries are experiencing "double peaks" in infection rates simultaneously, a key concern about BA.2 is that whether it could re-infect people who had already had BA.1. But data from both the UK and Denmark show that while Omicron can reinfect people, who had other variants, like Delta, only a handful of BA.2 reinfections in people, who earlier had BA.1 have been found so far. According to the scientists, a explanation for the recent spike in BA.2 cases could be the global uptick happened at the same time in many countries after lifting of public health interventions. "In some ways, it could just be that BA.2 was the variant that was circulating when all these people stopped wearing masks," said Dr Andrew Pekosz, virologist, Johns Hopkins Bloomberg School of Public Health in Baltimore. Other US experts, such as Eric Topol, director, Scripps Research Translational Institute in La Jolla, California, said it was "a little too early" to call whether the US too would see a significant BA.2 wave. "It is still a huge public health problem and it is going to continue to be," said Mark Woolhouse, epidemiologist, the University of Edinburgh. (With inputs from agencies)

'Stealth Omicron': BA.2 is now globally dominant Covid variant

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India Covid: New JN.1 sub-variant causes worry, India report 4,097 active cases

'Stealth Omicron': BA.2 is now globally dominant Covid variant

WHO: Sub-variant of Omicron detected in 57 countries, likely to be more severe