What is driving a surge in COVID cases in India, other countries?

Al Jazeera

a day ago

India has reported a sudden rise in COVID cases, starting from late May. Authorities said the number of active cases of the disease has surpassed 5,000.
India is the latest of a number of countries to report an uptick in COVID cases this year as, more than five years after the virus was declared a global pandemic, waves of new strains continue to emerge.
Here is what we know about the new variant of COVID and where it has spread:
As of Thursday this week, there are 5,364 active cases in India, according to India's Ministry of Health and Family Welfare. Since January 1, more than 4,700 people have recovered from COVID in India, while 55 people have died from the virus.
The main coronavirus variant causing a new spread of the disease is known as NB.1.8.1. Cases caused by this variant have been reported in the United Kingdom, the United States, Australia, Thailand, China and Hong Kong, among other countries. It is now the dominant variant in China and Hong Kong.
A second variant, LF.7, is also responsible for some of the cases in India.
The UK Health Security Agency (UKHSA) said it had recorded 13 cases of the NB.1.8.1 variant in England, with 'small numbers' detected across the UK.
By late April, NB.1.8.1 comprised about 10.7 percent of submitted sequences globally, according to the World Health Organization (WHO). This rose from just 2.5 percent one month before.
The Omicron variant NB.1.8.1 was first detected in January this year.
It is a 'recombinant' variant, which means it has arisen from the genetic mixing of two or more existing variants.
On May 23, 2025, the WHO declared the NB.1.8.1 strain a 'variant under monitoring' (VUM).
According to a 2023 definition by the WHO, a VUM is a variant which has undergone genetic changes that scientists believe could potentially affect the behaviour of the virus; early data suggests that this variant can grow faster or spread more easily than others, but this has not yet been confirmed.
The evidence of the variant's impact on health, immunity or transmission is still unclear.
While the NB.1.8.1 strain is still being researched, the evidence so far suggests that the strain may spread more easily, virologist Lara Herrero wrote for The Conversation on May 28.
Researchers using lab-based models have found that of several variants tested, the new strain had the strongest ability to bind to human cell receptors. This suggests that the strain may 'infect cells more efficiently than earlier strains', Herrero wrote.
'It is more transmissible,' Subhash Verma, a professor of microbiology and immunology at the University of Nevada, Reno School of Medicine, told CBS News.
Common symptoms of the NB.1.8.1 strain include a sore throat, cough, muscle aches, fever and nasal congestion.
It can also cause gastrointestinal symptoms such as nausea and diarrhoea.
Vaccines remain a powerful defence against COVID infections, severe sickness, hospitalisation and death, clinicians say.
However, virologist Herrero wrote that besides spreading more easily, NB.1.8.1 may 'partially sidestep' immunity gained from the vaccines or prior infection.
For now, health authorities say current COVID jabs are expected to be effective against this coronavirus variant and protect people from severe illness.
Health experts worldwide say there is no evidence that the new strain of the coronavirus is more severe or deadly than any previous strain. However, it does appear to spread more easily.
Since COVID spreads through airborne particles and droplets, the spread of the virus can be prevented by getting tested if symptoms show, wearing a mask and social distancing, clinicians have advised.