Fears the coronavirus pandemic would cause unprecedented death and misery once it reached India have so far proved unfounded, at least according to official statistics.
Flashback to September last year. The world's second-most populous country was recording nearly 100,000 confirmed infections of COVID-19 every day, and the daily death toll had surpassed 1000.
With massive cities of densely-packed people with limited incomes or access to medical care, it was assumed India's outbreak would quickly surpass the United States, the UK and Brazil as the world's worst.
But that doesn't appear to have happened. Since September, the number of daily new confirmed cases has dropped to about 10,000 and the death toll to just dozens a day - quite a feat for a country of 1.3 billion people.
While India's death toll of 155,000 is the second-highest in the world to date, per capita it rates 109th - and its current daily figures are just a fraction of those still being recorded in wealthy nations like the US, UK, Germany and France. Delhi, a city of 19 million people, didn't record a single death on Tuesday.
So how is this possible? Experts this week have been poring over the possibilities.
Vaccines
India's inoculation programme started in January, using two different vaccines - one developed by local firm Bharat Biotech and the other by Europe's AstraZeneca and the University of Oxford.
Both need two doses to reach maximum efficacy, but so far only 8.7 million doses have been administered - nowhere near enough the level required to reach herd immunity (expected to be upwards of 70 percent of the population). Earlier this week the Hindustan Times reported only 4 percent of people who got their first jab in early January have shown up for the second.
Besides, India's drop in new cases began in September - long before any vaccines were available.
Herd immunity
Once enough people have immunity to a virus, it has trouble finding new hosts - preventing outbreaks and protecting people who can't be vaccinated (eg. because of age or medical reasons).
But there's no evidence India has reached this stage yet. While studies looking at blood tests have suggested COVID-19 infections have been vastly undercounted wherever there has been a large outbreak, BBC News reports the latest testing shows no part of India is close to 70 percent.
"There is no region in the country which can be deemed to have attained herd immunity, though small pockets may exist," Public Health Foundation of India president K Srinath Reddy told BBC News.
In some parts of the country - such as densely populated slums - between a quarter and a third of people have tested positive for antibodies to the virus, well below herd immunity level.
"We still don't have causal explanations. But we do know India as a nation is far from herd immunity," Bhramar Mukherjee, a professor of biostatistics and epidemiology at the University of Michigan, told BBC News.
Lockdowns and other restrictions
For all we hear about New Zealand's strict lockdown preventing a widespread outbreak, India went even harder, going by the Oxford COVID-19 Government Response Tracker. On a scale of one to 100, until this week's Auckland outbreak New Zealand's response "strictness" was sitting at 22, while India's hasn't been below 61 since March 2020.
Many Indian cities have compulsory mask-wearing, but not all, and the decline in new cases has been seen nationwide, Sky News reports, making it hard to credit them as the major driver of the decline.
"India's lockdown was largely considered effective, and it was widely obeyed," the New York Times reported.
Demographics and living/working conditions
Some scientists have suggested India's youthful population is providing some protection. Half of all Indians are 26 or younger, and COVID-19 is known to be less severe and more likely to be asymptomatic in younger people.
Two-thirds of Indians also live and work in the countryside, where homes are typically well-ventilated and most work outdoors. Studies have found the coronavirus is far more likely to be caught indoors.
"The transmission risks are lower for persons working in open or semi-closed ventilated spaces," Dr Reddy told BBC News.
Others have suggested the squalid conditions many Indians grow up in hardens their immune systems. Even before case numbers began falling in September, India had one of the lowest case-fatality ratios in the world - meaning if you were an Indian confirmed to have COVID-19, despite the country's relative poverty, you were more likely to survive than someone in Italy, for example.
"If the COVID virus can be controlled in the nose and throat, before it reaches the lungs, it doesn’t become as serious - innate immunity works at this level, by trying to reduce the viral infection and stop it from getting to the lungs," Shahid Jameel of Ashoka University told the Associated Press.
"If we have had a massive number of very mild or asymptomatic cases, we might have reached a threshold of herd immunity already," Partha Mukhopadhyay of Delhi's Centre for Policy Research told BBC News.
The numbers are wrong
Studies around the world looking at excess mortality rates - comparing the number of deaths recorded to how many should have been expected, based on normal patterns - have consistently found more people have likely been killed as a result of the pandemic than official figures suggest. The discrepancy could be as much as 50 percent in some places, according to some counts.
Some Indian states last year were found to be misattributing COVID-19 deaths to other causes, for example.
BBC News reports India has a "poor record of certifying deaths" and many "die at home" and wouldn't be entered into the system as a COVID-19 death, particularly in rural areas.
It's not over yet
COVID-19 is still a new disease, caused by a virus that is registering more and more mutations, the more people it infects - and there are concerns being exposed to one strain won't offer people much protection from others.
So far about 178 people in India have tested positive for the potentially more deadly UK variant of the virus, but no deaths have yet been recorded.
In many parts of India life has returned to normal, the Associated Press reports, despite the threat of a second wave.
"We don't know if this will come back after three to four months," Georgetown University health economist Jishnu Das told the Associated Press.
