VIRUSES far more devastating than the coronavirus that causes Covid-19 have plagued humankind. Smallpox, for example, killed up to 30 per cent of people it infected. Thanks to science, it’s now a plague of the past, with the last natural infection occurring in 1977.

But the last cases of smallpox came from a lab, when a British medical photographer was accidentally infected at the University of Birmingham Medical School in 1978. She died after transmitting the virus to her mother, but fortunately, it did not spread further. The respected virologist who headed the lab died by suicide, with colleagues saying he was hounded to death by journalists looking for someone to blame.

The year before, the world was swept by the 1977 influenza pandemic, caused by a previously extinct strain of influenza. While some have suggested this pandemic was triggered by a lab accident, many scientists (including me) think it most likely resulted from a misguided vaccine trial.