Working with viruses entails working with needles, so it's not ridiculous to foresee an event where a shaky hand or muscle memory could fail and cause you to in

Working with viruses entails working with needles, so it's not ridiculous to foresee an event where a shaky hand or muscle memory could fail and cause you to inject yourself. In the case of the Ustinov incident, he was attempting to inject a guinea pig with an engineered version of what the Soviet Union had acquired from Kenya, and the guinea pig squirmed at just the wrong moment. Historically it may have been the highest viral load of Marburg Fever a human being has ever been exposed to. Ustinov took notes of his own deteriorating condition while his wife, who was also a researcher at the same lab, watched from outside the quarantine ward as his own organs liquefied into black goo. Eventually he was no longer able to use his own hands to write, fading in and out of consciousness, and he died two weeks later after the Soviet Union had exhausted its entire stock of Marburg antiserum. It was not a pleasant time. Working on animals also entail working with needles, since in most cases you need to inject them with things that aren't airborne or aerosolized.