On this day in 2020, the Moderna COVID-19 vaccine entered phase 1 trials, making it the first COVID vaccine to do so. This came less than a week after the World Health Organisation declared COVID-19 a global pandemic. How was it possible for this to happen so quickly? The third part of the #ChemVsCOVID series, produced with the Royal Society of Chemistry, gives a brief overview of the prior work and what the phase 1 trials looked at.