Row over use of calf serum in Covid-19 vaccines

Union Health Minister Harsh Vardhan on Wednesday said newborn calf serum is used as a “standard enrichment ingredient” to grow only laboratory cells that are used to produce a specific SARS-CoV-2 strain used as a vaccine.

"The final vaccine does not contain newborn calf serum at all. The calf serum is not an ingredient of the final vaccine product," the minister said, countering a social media campaign.

This technique has been used for decades in polio, rabies and influenza vaccines.

Newborn calf serum is used only for preparation or growth of vero cells that are standard base material to create a cell line in a laboratory. Such cells are used to establish cell lines, which help in production of vaccines.

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Different kinds of bovine and other animal serum are standard enrichment ingredients used globally for cell growth.

The vero cells, after the growth, are washed with water, with chemicals (known as buffer), many times to make it free from the newborn calf serum. Subsequently such cells are infected with coronavirus for viral growth.

The vero cells are completely destroyed in the process of viral growth after which the laboratory grown virus is killed (inactivated) and purified to make the vaccine, which contains no calf serum.

In a separate statement, Covaxin manufacturer Bharat Biotech said, “Newborn calf serum is used in the manufacturing of viral vaccines. It is used for the growth of cells, but neither used in growth of SARS-CoV-2 virus nor in the final formulation. Covaxin is highly purified to contain only the inactivated virus components by removing all other impurities.”