Watch: Moderna CEO Stephane Bancel testifies before Senate on Covid vaccine price hike

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Moderna's CEO, Stephane Bancel, is testifying Wednesday before the Senate health committee on pricing of the company's Covid-19 vaccine.

The Boston biotech company plans to charge $130 per dose once the vaccination program moves to the private market as early as this fall. Sen. Bernie Sanders, I-Vt., chair of the health committee, slammed Moderna in a letter to Bancel in January, calling the price hike "outrageous."

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After Sanders sent the letter, Moderna said it will create an assistance program to keep the vaccine free for people who are uninsured or underinsured.

People who have Medicare, Medicaid or private insurance should still receive the shot at no cost, but Sanders said the price increase "will cost taxpayers billions of dollars."