NEW DELHI—Scientists are trying to understand the role coronavirus variants, including a new one known as B.1.617, are playing in the world’s fastest-growing surge of Covid-19 cases in India.
The flood of cases threatens to cripple the healthcare system in India, where hospitals in the hardest-hit cities have been running out of oxygen and turning away patients. The country is battling the world’s fastest-growing coronavirus surge and has only a 1.9% vaccination rate.
Public-health experts say that the wave of infections appears to be driven by many of the same causes that have led to rising case counts elsewhere—primarily a relaxation of pandemic control measures—but that there are strong indications variants are also a factor.
Although little is known about the variant so far, scientists say that early data suggests that B.1.617, first discovered in India in a sample collected in October, is more contagious than the original version of the virus and has spread rapidly through parts of the country, including the state of Maharashtra, home of the financial capital Mumbai.
Public-health experts said they have been caught off guard by the sheer escalation of this wave, which tore through the population at a faster clip than some previous surges in other countries.
In mid-February, India’s daily case count had dipped below 10,000 and deaths had fallen to double digits. But since then cases began to increase rapidly. On Sunday, officials reported more than 3,600 deaths and 390,000 new cases, numbers that public-health experts say likely undercount the toll because so many people are dying outside overfilled hospitals.
The situation has led some desperate citizens to try to re-create intensive-care units at home, though oxygen tanks are hard to come by
New virus variants have been behind previous surges elsewhere, for example in the U.K. late last year. But India’s recent rate of increasing cases has been far faster than in the country’s previous wave, and swifter than the more gradual increases widely seen elsewhere. In the U.S., for example, the last big wave built up over three months, starting in September, and hit a peak of 295,215 daily cases on Jan. 8.
Concerns over the variants and high number of cases prompted the Biden administration to restrict travel from India beginning Tuesday, the White House said Friday. Australia and New Zealand, which have largely contained the virus, are threatening their own citizens with jail time or heavy fines if they try to get home from the South Asian country.
The U.K., Canada, Germany and France are among the growing list of countries that have also banned most travelers from India in recent weeks.
This current wave, scientists say, came after many people dropped mask-wearing and other safety precautions, and the government allowed huge political rallies and religious festivals, which may have been superspreader events.
“India had a double whammy,” said T. Jacob John, a retired professor of virology at the Christian Medical College in India’s southern city of Vellore. “We let our guard down when the variants were spreading. It was the worst time to do so.”
Variants spreading through the population likely added fuel to the fire. The variant that first appeared in the U.K., as well as those that first appeared in Brazil and South Africa, have also been detected in India, according to the Health Ministry.
The B.1.617 variant has 13 mutations, two of which are similar to those seen separately in other variants. In other variants, one mutation is associated with making the virus more infectious and appears better at evading antibodies, while the other is similar to one that has shown signs of being able to sidestep some of the body’s immune responses.
It was first discovered in India in a sample collected in October, said Dr. Rakesh Mishra, director of the CSIR Centre for Cellular and Molecular Biology, which operates one of the 10 state-run labs charged with genomic sequencing of the virus. Recent data points to its rapid spread through some regions of India.
In the hard-hit state of Maharashtra, the B.1.617 variant has already become the dominant strain, according to Dr. Anurag Agrawal, director of the CSIR Institute of Genomics and Integrative Biology. In samples collected in the state from January to March, over 60% were of the B.1.617 variant, according to a study by the National Institute of Virology in Pune.
For the country overall, this variant made up 70.4% of the samples collected during the week ended March 25, compared with 16.1% just three weeks earlier, according to Covid CG, a tracking tool from the Broad Institute of MIT and Harvard. The tool uses data from the GISAID Initiative, a global database for coronavirus genomes.
“Once it becomes a dominant variant somewhere, it becomes concerning because that means it might soon become the dominant variant somewhere else,” said Alina Chan, a postdoctoral researcher focused on gene therapy and cell engineering at the Broad Institute of MIT and Harvard.
Scientists in India, the U.S. and other countries are studying the variant in labs to see how the virus responds to antibodies. But even without knowing how the variant reacts to vaccines or the body’s immune response, scientists say B.1.617 has the potential to drive other infections around the world.
The virus has already hopped to at least 21 countries, according to researchers at four universities that track viral lineages. Genetic sequencing has turned up cases in the U.S., Germany, Turkey and Nigeria, among others. In the U.K., genome sequencers have found the variant among people who haven’t traveled, suggesting it has spread within the community.
In Australia, the B.1.617 variant made up 40% of the samples collected over the week ended April 15, compared with 16.7% a month earlier, according to Covid CG. It accounted for 66.7% of samples from New Zealand for the week ended April 8, up from 20% a month ago.
In California, at least 20 confirmed or presumptive cases of the B.1.617 variant have been discovered since late March, according to Dr. Benjamin Pinsky, director of Clinical Virology Laboratory at Stanford University. Dr. Pinsky said samples have already been sent to collaborators at other laboratories, where research is under way to test how the virus reacts to monoclonal antibodies and plasmas from infected or vaccinated people.
That research could inform future vaccine development, especially booster shots that will target particular variants of Covid-19, Dr. Pinsky said.
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