NEW DELHI — India’s ambitious but troubled campaign to vaccinate its vast population against Covid-19 — and, in the process, to burnish its own reputation as a manufacturer and innovator — just got a big boost.
An Indian drug company said late Wednesday that initial results from clinical trials involving nearly 26,000 subjects showed that a homegrown Indian vaccine was both safe and effective. The company, Bharat Biotech, said that its Covaxin vaccine had an initial efficacy rate of 81 percent.
The results from the interim analysis have yet to be peer reviewed, the company said. It was unclear how effective Covaxin would prove to be in a final analysis.
Still, the results were met with relief in India. Covaxin had been approved by government officials in January and administered to millions of people before it had been publicly proved to be safe or effective. Many people in India, including frontline health care workers, had feared Covaxin could be ineffective or worse, slowing down New Delhi’s campaign to inoculate 1.3 billion people.
Officials in Brazil, where the government had bought doses of Covaxin, had recently questioned whether this vaccine actually worked.
The results this week could alleviate some of those concerns, said Dr. Anant Bhan, a health researcher at Melaka Manipal Medical College in southern India. Still, he said, questions will linger over Covaxin until the research is completed.
“This data will now need to be examined by the regulator in India and could then have an impact on the regulatory decisions with regards to the vaccine,” Dr. Bhan said.
If the results hold, they could also benefit Narendra Modi, India’s prime minister, and his Hindu nationalist political party. Mr. Modi has stressed making India self-reliant, and an effective, Indian-developed vaccine could help that campaign.
India’s approval of Covaxin for emergency use was announced in early January on the same day as approval of the Oxford-AstraZeneca vaccine, which is known in India as Covishield. When the vaccination drive started less than two weeks later, most people were not allowed to choose which jab they got.
To support the vaccine, Mr. Modi publicly took the Covaxin jab on Monday. Images of other federal ministers and heads of regional governments taking the Indian-made vaccine were posted on social media.
But Gargeya Telakapalli, a public health expert, said the emergency approval of Covaxin raised suspicions among frontline workers and prompted questions about India’s regulatory process. That added uncertainty to the vaccination process in general.
“I know many health care workers who were not very confident to take Covaxin and preferred Covishield,” said Mr. Telakapalli, who works in India with the People’s Health Movement, a global network of grass-roots health activists. “The rush for the approval has not helped Covaxin, although no one is saying there is any problem with the vaccine.”
In part because of the risk of getting a vaccine that hadn’t been proved safe, many people in India have declined to get jabbed, contributing to the slow rollout of the campaign. The effort to vaccinate the country’s huge population was already logistically challenging, involving transporting doses to far-flung places while controlling the environment around them.
The government aimed to vaccinate about 300 million people by August. As of Wednesday, it had inoculated about 16 million. At that rate, covering the population could take years. The authorities have expanded eligibility from essential workers to include people over 60 and those above 45 with significant health risks.
Last week, an advisory board for Central Drugs Standard Control Organization, India’s pharmaceutical regulator, rejected Bharat Biotech’s request for a Covaxin trial on children between the ages of 5 and 18, saying the company should first submit a report on the efficacy of its vaccine.
The uncertainty could hinder Bharat Biotech’s ambitions to sell Covaxin to countries like Brazil. Last week, prosecutors there sought the immediate suspension of Covaxin purchases after the government signed a contract to buy 20 million doses.
The company has been undaunted. Bharat Biotech, which developed Covaxin with the National Institute of Virology and the Indian Council of Medical Research, has already supplied 5.5 million shots of its vaccine for the Indian government’s vaccination campaign.
On Wednesday, the company said the final stage of the Covaxin trial had involved 25,800 volunteers across the country.
Officials at the Indian Council of Medical Research said in a statement that the eight-month effort to produce a locally made vaccine was a testament to the country’s emergence as a global vaccine superpower.
“The development and deployment of Covaxin ensures that India has a powerful weapon in its arsenal in a continually evolving pandemic situation and will go a long way in helping us win the war against Covid-19,” said Dr. Samiran Panda, an official at the council.