New evidence confirms COVID-19 vaccines are overwhelmingly safe::More than 38 million COVID-19 vaccine doses have been administered in Ontario as of Oct. 8, with 23,002 reports of adverse reactions, an incidence of 0.06 per cent, Public Health Ontario says
They’ve been developing it since the first SARS.
Edit: I was wrong, they started developing MRNA vaccines in the 1970s.