covid19 vaccines go through a demanding, multistage testing process, including large trials that involve tens of thousands of people.

amachiza okugonyela icovid19 afakwa phantsi kweenkqubo zovavanyo ezingqongqo nezingamanqanaba amaninzi, ezi quka iimvavanyo ezinkulu ezibandakanya amashumi amawaka abantu.
