NEW DELHI  — India has dramatically increased COVID-19 vaccination rates in its vast rural hinterland, where around 65% of the country's nearly 1.4 billion people live. But supply constraints remain for the world's largest maker of vaccines and experts say it's unlikely India will reach its target of vaccinating all adults by the end of the year.

India opened shots for all adults in May. But the campaign faltered in villages due to vaccine hesitancy and misinformation. That started changing in mid-July and of the nearly 120 million shots administered in the past three weeks, around 70% were in India's villages — up from around half in the initial weeks of May.

Although the increased vaccine acceptance in rural areas is promising, the pandemic is far from done in India: After weeks of steady decline, the 46,000 new infections reported Saturday was its highest in almost two months.

Only about 11% of India's vast population is fully vaccinated. Half of all adults and about 35% of the total population have received at least one shot. This has left large swathes of people still susceptible to the virus.

Several nations, including the U.S. and Israel, are offering or plan to offer booster shots to people, deepening global vaccine inequity. India was expected to be a pivotal producer of shots to immunize the world but stopped exports after an explosion of infections. And while India had expected to get 1.35 billion shots in the final five months of 2021 to resolve its supply constraints, the question of whether Indian vaccine makers can scale up production to meet India's needs will have global implications.

“Currently in India, there is more demand than available supply…the supply of vaccines currently in use is lower than the projections made a few months ago. So both of these situations are putting constraints on availability of vaccines in the country," said Dr. Chandrakant Lahariya, a vaccine policy expert.

India is no stranger to mass immunizations, but this is the first time that shots are being given at this scale, and to adults. Officials have blended strategies that were successful in the past with newer, more localized innovations.

Kamalawati, 65, a retired government accountant who goes by only her first name, lined up for a shot at Nizampur, a village outside New Delhi. She said people initially were concerned there would be harmful side effects but “people are not scared anymore.”

What has worked for her village and others is a contest in which the local government awards a trophy to the village with the most vaccinated people and a plaque declaring the village the winner. Stickers are also pasted on homes where people are fully vaccinated to encourage neighbors to do the same. District administrator Saumya Sharma said the campaign banks on the sense of community and pride residents have in their village. "That this is our village. And we are going to make it No. 1,” she said.

In Juggar, home to several thousand of the over 155 million people who live in rural parts of India's Uttar Pradesh state, villagers refused the vaccine when health officials first arrived there, paramedic Ravi Sharma said. Only after family members of health workers got their shots in public view did others begin to get the vaccine.

Millions of people from eastern Bihar state, one of India's least urbanized, migrate to the Middle East for work. With international travel impossible without certificates showing full vaccination, more people are signing up for jabs, said Dr. R.K. Chaudhary, who is in charge of a rural health center in Phulwari Sharif village.

These strategies rest on methods that have worked in past vaccination campaigns. Performers with drums and clad in traditional attire are fanning out to Indian villages to underline the importance of getting the shot. Several states have organized mobile vaccination centers, where shots are given at highly visible places in village squares. The government has also used WhatsApp, which is ubiquitous in India, to help people book appointments for vaccines.

Public health experts say the uptick in rural vaccinations is important because health care systems in villages are fragile. The deadly surge of infections that overwhelmed hospitals earlier this year ripped through rural India and thousands died. Moreover, migrants from villages move to cities for work and until everyone is vaccinated, outbreaks and even the possibility of a dangerous new variant can't be discounted, said Lahariya.

India has the infrastructure to vaccinate up to 10 million people daily, but is averaging between 5 million and 6 million, he said.

So far, nearly 90% of the vaccines administered were the AstraZeneca shots made by the Serum Institute of India. The government hopes to solve the supply constraints that have hamstrung the vaccination effort with new production lines as well as the approval of a new homemade vaccine and another in the pipeline.

India hopes that Bharat Biotech will make around a third of the 1.3 billion shots it needs. The company has struggled so far in scaling up and while a new facility, capable of making 10 million shots monthly, began production last week, the company is looking for international manufacturing partners.

The Russian-made Sputnik V vaccine was given the nod by Indian regulators in April but accounts for less than 1% of total vaccinations. The company has arranged with several Indian vaccine makers to start making shots locally, hopefully by later this month.

India expects 100 million Sputnik V shots and 50 million shots of Indian drugmaker Zydus Cadila’s recently greenlit COVID-19 vaccine later this year.

Apart from this, the regulator approved Moderna's COVID-19 vaccine in June and the single-dose Johnson & Johnson shot in August. But it is unclear when they will be administered.

Meanwhile, Moderna and Pfizer have been discussing the signing of indemnity waivers for their vaccines for weeks with India's federal government. Unlike some other countries and the U.N.- backed COVAX initiative, India doesn't have a mechanism in place for people who suffer rare side effects to seek compensation, said Lahariya. He said these discussions were an opportunity to reexamine accountability and create a system where people are protected.

Lahariya warned that even though he expected supply to improve, it was unlikely that India would have enough shots to immunize all adults by the end of the year. “No matter what,” he said.