The WHO approved the vaccine’s use in people aged 18 and older on a two-dose schedule with four weeks between shots, according to a statement on Wednesday. Covaxin joins a range of WHO emergency-cleared shots from AstraZeneca Plc, China’s Sinopharm Group Co. and Sinovac Biotech Ltd., Pfizer Inc. and BioNTech SE , Johnson & Johnson and Moderna Inc.

The agency’s nod is a welcome endorsement for Covaxin’s manufacturer Bharat Biotech International Ltd. The Hyderabad-based company has been beset with problems since it partnered with the state-funded Indian Council of Medical Research last year to develop the inoculation. 

Covaxin has been criticized from the onset. The vaccine won emergency approval from the nation’s drug regulator in January before clearing final-stage clinical tests, fueling hesitancy around the shot and the early stages of India’s immunization drive.

More than 100 million doses have since been administered across India. Bharat Biotech said in July that the vaccine was 77.8% effective in preventing symptomatic COVID, but that Phase 3 data was yet to be peer reviewed. In the course of its analysis, the WHO repeatedly asked the company for further information, delaying its addition to the body’s pre-qualified list.

The listing is a prerequisite for exports via the WHO-backed Covax vaccine-sharing facility, which was set up to provide COVID shots to the world’s poorest countries. The WHO’s approval may accelerate the resumption of vaccine shipments from India, which halted exports in April to prioritize its own citizens amid a lethal second coronavirus wave.

India will likely restart vaccine exports to Covax by early November, Adar Poonawalla, head of the Serum Institute of India Ltd., told Bloomberg News last month. Serum, the world’s largest vaccine maker, has pumped out hundreds of millions of doses of AstraZeneca’s inoculation and the company was meant to be the main provider of vaccines to Covax before the export halt. 

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