The vaccine, made by India's Bharat Biotech and with a 78-percent efficacy rate after two doses over a month "is extremely suitable for low- and middle-income countries due to easy storage requirements," the UN body said.
Covaxin is the first vaccine completely developed and manufactured in India to receive WHO approval.
Unlike mRNA vaccines by Pfizer/BioNTech and Moderna that have emerged as leading jabs against Covid-19, Covaxin uses the more traditional "inactivated" technology that has been used for decades in vaccines against diseases like polio, seasonal influenza and rabies.
The technology uses a dead version of a germ that causes a disease to boost the immune response.
One of the main advantages of such vaccines is that they are more easily stored that mRNA jabs, which need to be kept at sub-zero temperatures. This makes them easier to distribute, especially in poor countries that may lack the needed facilities.
Covaxin can be stored between 2-8 degrees Celsius (36-46 degrees Fahrenheit), according to the company website.
India welcomed the move, with Foreign Minister Subrahmanyam Jaishankar tweeting that it "facilitates travel for many Indian citizens and contributes to vaccine equity."
Covaxin becomes the eighth vaccine against Covid-19 on the WHO's list, including others from Pfizer/BioNTech, Moderna, AstraZeneca, Johnson & Johnson, Sinopharm and Sinovac.
WHO emergency approval, which includes an assessment of clinical trial data, can speed up international recognition of vaccines.
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