India has administered more than a billion Covid jabs since it started its vaccination drive in January this year.
It achieved this milestone in 278 days – the first vaccine was given on 16 January.
It has fully vaccinated about 30% (291 million) of the eligible population and 707 million have had the first dose.
India aims to fully vaccinate about a billion people by the end of 2021 but experts say the drive needs to pick up pace further to meet the target.
Reaching the one billion mark in 278 days means that India, on an average, administered 3.6 million doses per day. However, the number of doses actually administered each day since January was not consistent, and varied widely.
So far, the country has reported more than 34 million Covid cases, second only to the US, and more than 452,000 deaths – behind the US and Brazil.
In the last 24 hours, India has give more than four million jabs.
Experts estimate that the country needs to give more than 10 million doses a day to fully vaccinate all eligible adults by the end of 2021.
This daily estimated target, however, has only been achieved on six days so far.
On 17 September, India administered more than 20 million doses in a day in a record-breaking effort to mark Prime Minister Narendra Modi’s 71st birthday.
Experts say record-breaking days are encouraging but vaccination rates need to rise consistently.
In October, India administered an average of 5.3 million doses per day. From 19 September to 18 October, the average daily doses given slightly improved to six million. This is still far below the required 10 million jabs that experts say are needed to meet the target.
India had a slow start when vaccinations were opened for some 960 million eligible people.
Logistical problems and supply bottlenecks, vaccine hesitancy and a debilitating second wave of Covid-19 during this period made the rollout harder.
India is still around 900 million jabs away from a fully vaccinated adult population, with little less than two-and-a-half-months to spare on the target.
Much will depend on levels of vaccine hesitancy and the availability of doses in the coming months.
From a sluggish start, India massively ramped up its vaccination drive, with more than 61,000 public and private health facilities offering the jab.
The country has also started delivering vaccines by drone to far-flung villages in north-east India’s mountainous regions.
Drones will also be used to ferry doses to the eastern archipelago of Andamans and Nicobar where “transportation by boat” was taking a long time.
The government is using drones which can carry a payload of 4.5kg or a maximum of 900 doses and fly at least 70km (43 miles) to ferry doses.
India’s daily case count has been dropping – it has been reporting less than 30,000 new daily cases in the past month, and less than 20,000 in the past 10 days.
While the vaccination drive has gained momentum, experts worry about a gender gap – government data shows 6% fewer women are getting vaccinated. This is especially true in rural India where women have limited access to the internet and are hesitant or scared to take the vaccine.
Although a higher number of doses are being administered daily in rural areas, the share of population being vaccinated in urban areas is still greater.
Most countries, especially those in the developing world, have struggled to access vaccines – a challenge that India, as the world’s largest vaccine maker, didn’t expect to face.
But Mr Modi’s government didn’t place orders from vaccine makers early enough – and a devastating second wave in April pushed them to expand the drive too quickly to the entire adult population, which is nearly a billion.
In June, the government told the Supreme Court that 1.35 billion doses will become available between August and December. It would take about 1.8 billion doses to vaccinate all eligible adults in India.
India is using three vaccines – the Oxford-AstraZeneca jab, known locally as Covishield; Covaxin by Indian firm Bharat Biotech; and Russian-made Sputnik V.
India has also approved its first vaccine for those under 18.