The Chinese Covid-19 vaccine has an unlikely USP over others: A tiny label that can monitor heat damage. The label, better known as vaccine vial monitor, has been a part of mass vaccination such as polio drives in India because it has a heat-sensitive chemical that tells health workers if a vial was stored correctly or damaged due to exposure to heat. It is the easiest way to find out if the cold chain to store certain vaccines was maintained or not.
