A clinician preparing to administer the Janssen Covid-19 vaccine which only requires on dosage. Johnson & Johnson's long-awaited Covid-19 vaccine appears to protect against symptomatic illness with just one shot. All Covid-19 vaccines train the body to recognise the new coronavirus, usually by spotting the spikey protein that coats it. Rival AstraZeneca makes a similar cold virus vaccine that requires two doses. J&J said the vaccine is safe, with reactions similar to other Covid-19 shots such as fever that occur when the immune system is revved up.

Source: New Zealand Herald January 29, 2021 17:48 UTC