From doctors weary of seeing patients die to relatives who lost their loved ones, thousands of Brazilians, like nurse Jane Cristina Dias Alves, have volunteered for COVID vaccine trials in one of the world's worst-affected countries in the hope their quiet heroism will save lives.
Latin America's largest country has become a major testing ground for vaccines because of the scale of its outbreak, which has seen more than 7.3 million people infected and over 180,000 killed by the coronavirus.
Some shrugged off what they said were mild side effects from the inoculation.
"The first days after I took (the vaccine), I had a few symptoms – shivers and pain in my body," said Antonia Santos, a nurse who participated in the AstraZeneca trial. "My daughter was desperate. She said 'Mom, you are crazy.' I said, 'No, crazy would be not to take it.'"