Serum Institute of India, which makes the most used Covid-19 vaccine in the country, on Saturday defended pricing Covishield vaccine at 1.5 times the initial rate, saying the earlier price was based on advance funding and now it has to invest in scaling up and expanding capacity to produce more shots.

Serum Institute of India (SII), which manufactures AstraZeneca's vaccine Covishield at its Pune facility, earlier this week announced a price of Rs 600 per dose and at Rs 400 for state governments and any new contract by the central government.

This compared to Rs 150 per dose it charges the central government for the existing supplies.

"There was an inaccurate comparison done between the global prices of the vaccine with India," SII said. "Covisheld is the most affordable Covid-19 vaccine available in the market today."

The initial price, it said, was "kept low globally as it was based on advance funding given by those countries for at risk vaccine manufacturing."

"The initial supply price of Covishield for all government immunization programme, including India, has been the lowest," it said.

"The current situation is extremely dire, the virus is constantly mutating while the public remains at risk. Identifying the uncertainty, we have to ensure sustainability as we must be able to invest in scaling up and expanding our capacity to fight the pandemic and save lives."

SII went on to add that only a limited portion of SII's volume will be sold to private hospitals at Rs 600 per dose.

"The price of the vaccine is still lower than a lot of other medical treatment and essentials required to treat COVID-19 and other life threatening diseases," it added.