In this April 10, 2020, photo released by Xinhua News Agency, a staff member holds up a sample of a potential COVID-19 vaccine at a production plant of SinoPharm in Beijing. In the global race to make a coronavirus vaccine, the state-owned Chinese company is boasting that it gave its employees, including top executives, experimental shots even before the government OK'd testing in people. (Zhang Yuwei/Xinhua via AP)
A health worker holds a sample of a potential Covid-19 vaccine at a Sinopharm production plant. AP

Volunteers are indispensable to vaccine discovery