News in Focus GETTY Ahead of a Lockdown Imposed on 14 April, Migrant Workers Queue at a Railway Station to Leave the City of Mumbai, India

The world this week News in focus GETTY Ahead of a lockdown imposed on 14 April, migrant workers queue at a railway station to leave the city of Mumbai, India. INDIA’S MASSIVE COVID SURGE PUZZLES SCIENTISTS The virus is spreading faster than ever before in India, despite previous high infection rates in megacities, which should have conferred some protection.

By Smriti Mallapaty Delhi and Chennai had already been infected, Germany are also currently experiencing large leading some researchers to conclude that the outbreaks relative to their size, and nations he pandemic is sweeping through India worst of the pandemic was over in the country. including Brazil and the United States are at a pace that has staggered scientists. Researchers in India are now trying to pin- reporting infection rates of around 60,000– Daily case numbers have exploded point what is behind the unprecedented surge, 70,000 a day. But India’s daily totals are now since early March: the government which could be due to an unfortunate con- the highest recorded for any country, and have reported 352,991 new infections fluence of factors, including the emergence exceeded a peak of 300,000 cases seen in the Tnationally on 25 April. High numbers in India of particularly infectious variants, a rise in United States on 2 January. have also helped to drive daily global cases to unrestricted social interactions, and low vac- COVID-19 case numbers started to drop in a high of 899,755 in the past week, breaking a cine coverage. Untangling the causes could India last September, after a high of around record set in January. be helpful to governments trying to suppress 100,000 daily infections. But they began Just months earlier, antibody data had or prevent similar surges around the world. to rise again in March, and the current suggested that many people in cities such as European countries such as France and peak is more than double the previous one

News in focus (see ‘Surging cases of COVID-19’). SURGING CASES OF COVID 19 need to be cautious,” says David Robertson, “The second wave has made the last one look New daily cases in India have been rising rapidly since a virologist at the University of Glasgow, UK. like a ripple in a bathtub,” says Zarir Udwadia, March and have now far surpassed last September’s Some say that emerging variants account peak of around 100,000 new cases per day. a clinician-researcher in pulmonary medicine for only a small part of India’s surge in infec- at P D Hinduja Hospital & Medical Research 300 tions. In many regions that are experiencing Centre in Mumbai, who spoke to Nature dur- outbreaks, they don’t make up the majority ing a break from working in the intensive-care of genomes sequenced, says Anurag Agrawal, unit. He describes a “nightmarish” situation 200 director of the CSIR Institute of Genomics and at hospitals, where beds and treatments are Integrative Biology in New Delhi. in extremely short supply. Shahid Jameel, a virologist at Ashoka Uni- Mixing, moving and travelling versity in Sonipat, agrees that the intensity of 100 Srinath Reddy, an epidemiologist and head of the current wave is startling. “I was expecting cases (thousands)* the Public Health Foundation of India in New fresh waves of infection, but I would not have Daily confirmed COVID-19 Delhi, argues that people letting their guards dreamt that it would be this strong,” he says. 0 down is a bigger driver. “The pandemic resur- Studies that tested for SARS-CoV-2 antibod- Feb Mar Apr faced in a fully open society where people were

ies — an indicator of past infection — in Decem- *Seven-day rolling averages, up to 20 April. mixing and moving and travelling,” he says. IN DATA OUR WORLD SOURCE: ber and January estimated that more than 50% With cases declining after last September’s of the population in some areas of India’s large variant first identified in India late last year, peak, “there was a public narrative that India cities had already been exposed to the virus, known as B.1.617, has become dominant in the had conquered COVID-19”, says Laxminarayan. which should have conferred some immunity, state of Maharashtra. B.1.617 has drawn atten- In recent months, large crowds have gathered says Manoj Murhekar, an epidemiologist at the tion because it contains two mutations linked indoors and outdoors for political rallies, National Institute of Epidemiology in Chennai, to increased transmissibility and an ability to religious celebrations and weddings. who led the work. The studies also suggested evade immune protection. It has now been India’s vaccination campaign might even that, nationally, some 271 million people had detected in 20 other countries. Laboratories have contributed to an uptick in cases, if it been infected — about one-fifth of India’s in India are trying to culture it to test how fast it caused people to ease public-health measures. population of 1.4 billion (M. V. Murhekar et al. replicates, and whether blood from vaccinated “The arrival of the vaccine put everyone into a Preprint at SSRN https://doi.org/f73d; 2021). individuals can block infection, says Jameel. relaxed mood,” says Laxminarayan. These figures made some researchers opti- The situation in India looks similar to More than 140 million doses have been mistic that the next stage of the pandemic that late last year in Brazil, he adds, where a administered, mostly of an Indian version of the would be milder, says Ramanan Laxminarayan, resurgence of COVID-19 in the city of Manaus Oxford–AstraZeneca vaccine called Covishield. an epidemiologist with Princeton University in coincided with the spread of a highly transmis- But that covers less than 10% of India’s popula- New Jersey who is based in New Delhi. But the sible variant known as P.1, which might have tion, and vaccinations must be ramped up in latest urge is forcing them to rethink. been able to evade existing immunity. the hardest-hit regions, says Kang. One explanation might be that the first wave But others say that the existing sequencing Some people might have become infected mainly hit the urban poor. Antibody studies data are not sufficient to make such claims. “As while getting vaccines, says Udwadia, because might not have been representative of the the numbers of sequences available are low, crowds often share clinic waiting areas with ill entire population and potentially overesti- relative to the number of cases in India, we do people who are waiting to be seen. mated exposure in other groups, he says. The antibody data did not reflect the uneven spread of the virus, agrees Gagandeep Kang, a virologist at the Christian Medical College in Vellore, India. “The virus may be getting into populations that were previously able to pro- LIFT OFF! FIRST FLIGHT tect themselves,” she says. That could include wealthier urban communities, in which people ON MARS LAUNCHES NEW isolated during the first wave but had started mingling by the second. WAY TO EXPLORE WORLDS Fast-moving variants? NASA’s Ingenuity helicopter successfully hovered But some researchers say that the speed and scale of the current outbreak suggest a new for 40 seconds in Mars’s thin atmosphere. ingredient: emerging variants of the virus. Udwadia has anecdotally observed that By Alexandra Witze Jet Propulsion Laboratory (JPL) in Pasadena, entire households are now getting infected — California. unlike in the first wave of COVID-19, when single ASA has pulled off the first powered Ingenuity’s short test flight is the off-Earth individuals would test positive. He attributes flight on another world. Ingenuity, equivalent of the Wright brothers piloting this to the presence of more-infectious variants. the robot rotorcraft that is part of their aeroplane above the coastal dunes at “If one person in the family has it, I can guaran- the agency’s Perseverance mission, Kitty Hawk, North Carolina, in 1903. In tribute, tee that everyone in the family has it,” he says. lifted off from the surface of Mars the helicopter carries a postage-stamp-sized Genomic surveillance data show that the Non 19 April, in a 39.1-second flight that is a piece of muslin fabric from the Wright broth- variant B.1.1.7, which was first identified in the landmark in interplanetary aviation. ers’ plane. “Each world gets only one first United Kingdom, has become the dominant “We can now say that human beings have flight,” says Aung. form of the virus in the Indian state of Punjab. flown a rotorcraft on another planet,” says The flight came after a one-week delay, And a new and potentially concerning MiMi Aung, the project’s lead engineer at the because software issues stopped the