India’s relatively mild first wave of COVID last year intrigued scientists and led the country’s leadership to declare what turned out to be a very premature victory over the novel coronavirus. The current surge has been much more deadly. Some researchers and media outlets have pinned the blame on new viral variants, which early studies suggest may be more transmissible than the original strain. But many experts familiar with the situation on the ground argue that large gatherings and crowds in closed, compact urban spaces—in contrast with the draconian lockdown imposed during the first wave—are driving most of the spread.

Both Prime Minister Narendra Modi and Mamata Banerjee, chief minister of the state of West Bengal, held crowded political campaign rallies during state elections in India even as COVID cases were spiking this past April. Later that month Modi told state leaders that a lockdown should be considered only as “a last option” as numbers rose across various states, eventually topping 400,000 daily new cases nationwide on April 30. India’s economy suffered significantly after the 2020 lockdown, so officials were under tremendous political pressure to avoid similar restrictions when cases started rising again in April. This time the central government left pandemic policy decisions to state governments—which were also loath to implement economically damaging restrictions.

“I think this is an important lesson to other countries. It is complacency and poor leadership that caused the surge,” says Carlos del Rio, a professor of medicine in the infectious diseases division at the Emory University School of Medicine. The sudden new spike simply overwhelmed India’s already ailing health infrastructure. Sumit Ganguly, a political scientist at Indiana University Bloomington, calls it “the chronicle of a disaster foretold.”

Epidemiologists agree that last year’s lockdown was extreme. More than 1.3 billion people were forced to remain inside their home for weeks at the outset of the pandemic. “The entire country shall go under complete lockdown. A total ban is being imposed [to prevent people] from stepping out of their homes for 21 days,” Modi announced in a televised address on March 24, 2020, when there were fewer than 600 confirmed COVID cases in the entire nation. The prime minister gave the country less than four hours before putting each state, municipality, village, street and household in complete lockdown. He argued that if the situation was not brought under control within 21 days, the country could be set back 21 years, and families would be devastated forever. This intensive and preemptive policy response was prompted by tangible fear among leaders and the public. The lockdown brought daily life to an immediate grinding halt—and also seemed extremely effective in limiting the spread of the virus.

The contrast between last year’s harsh lockdown and the government’s much more lenient second-wave response could not be more stark. Manoj Jain, an adjunct professor at Emory’s Rollins School of Public Health, agrees the lockdown worked well because it relied on strict police enforcement. But in hotspots such as Delhi and Mumbai, he says, even basic social distancing practices disappeared as the restrictions were lifted—which is proving costly now. It is likely that “loosening of activity restrictions does play a major role in the current transmission dynamics in India,” says Markus Hoffmann, a postdoctoral infection biology scientist at the German Primate Center–Leibniz Institute for Primate Research, who has published several papers on coronavirus transmission and infection. Scientific American reached out to the offices of India’s prime minister and the chief ministers of several of its states for comment but did not receive a response to its questions.

This time, rather than a nationally coordinated lockdown, India’s states were left to their own devices. Daily new infections in Maharashtra—the hardest-hit state during both the first and second waves—increased more than sixfold this past March. On April 4 its state government announced a ban on more than five people gathering in public places during the day on weekdays and on anyone being out at night or during the weekend without a valid reason (such as getting medicine for a family member). But the curfew appears not to have been enforced. Crowds of people, often not properly masked, were everywhere. Daily new cases continued to rise sharply. And as the new surge steadily overwhelmed the health infrastructure, Maharashtra repeatedly changed its guidelines. The state government provided scant information about what should be open or closed, making it difficult to enforce social-distancing rules. Maharashtra’s weekly average test positivity rate rocketed to 22.5 percent in the second week of May, with the figure climbing as high as 40 percent in some districts.

The union territory of Delhi, another hotspot, announced evening-only movement restrictions on April 6—after new cases in India’s capital grew more than 10-fold during March. But most daytime activities proceeded as usual. Restrictions on driving personal vehicles and using public transportation, within or between states, were not widely enforced. During most of the time new cases were surging, bars, restaurants, movie theaters, the metro system and buses were still operating (albeit at reduced capacity). Jain reasons that in crowded urban areas such as Delhi, it is nearly impossible to enforce social-distancing guidelines without a complete lockdown—and that less stringent measures would have done little to impede the spread of the virus, given its high transmissibility. Unsurprisingly, by April 22, Delhi recorded a test positivity rate of 36.2 percent.

Uttar Pradesh, India’s most populous state, also imposed only half-hearted restrictions during the second wave. It even went ahead with elaborate village council elections. A prominent teachers union in the state has asserted that more than 1,600 teachers who administered those elections died of COVID throughout April and May. (The state government says only three died of the disease, a claim contested by the teachers’ union, which has now released the names and addresses of those who had died.)

The new B.1.617.2 viral variant (now called the Delta variant) was first detected in India last December, and it has also been blamed for the rapid spread of COVID there. But Jain says more evidence is needed to determine whether this variant is truly more transmissible than the original strain—and whether it might evade the antibodies from a previous infection or vaccine. There is some indication that the Delta variant has played a significant role in the current growth of cases, although India has only sequenced the viral genomes involved in a tiny fraction of cases. Even if the Delta variant is shown be more transmissible, however, loosened restrictions probably provided the right set of conditions for the virus to spiral out of control. Evidence to date suggests the existing vaccines provide good protection against all known variants. A recent study by Public Health England found the Pfizer vaccine was 88 percent effective at preventing disease from the Delta variant, and the AstraZeneca vaccine was 60 percent effective Unvaccinated people remain vulnerable.

A convergence of factors—including an increase in potentially more transmissible variants, the lack of hospital infrastructure for treating COVID patients and the occurrence of possible superspreader social gatherings—may have caused a “perfect storm,” says S. V. Subramanian, a professor of population health at Harvard University’s Geographic Insights laboratory. He contends that India’s mass vaccination efforts themselves have probably been superspreader events. “The vaccine rollout in India has been a notable effort, given India’s poor public health infrastructure,” Subramanian says. “However, administering millions of vaccines through hospitals and health care centers—the last place one should be at this point, unless desperately needed—also is a cause for concern with likely overcrowding.”

The number of new infections in the country has declined significantly in recent weeks, but it is still extremely high. India is still seeing well over 100,000 new cases daily—a large proportion of the global number. To curb the spread, researchers say authorities could start with simpler, more easily implementable solutions, such as improved ventilation, mask wearing and social distancing. These simple strategies could be especially helpful in rural India, where most cases and deaths go undetected because many rural communities lack infrastructure for testing and treatment.

Emory’s Jain, who says he has been advising several Indian state governments on COVID-related issues, recommends preparing for a potential rural wave by engaging local village councils. And he suggests pharmacies could step in to help track infections in rural areas. Vaccinations also need to be stepped up, and they should be administered in large open spaces, such as sports stadiums. The vaccination drive, Subramanian says, is currently the single most unrestricted activity going on.