England’s deputy chief medical officer Van-Tam made the comment during the daily Downing Street press briefing on Wednesday.
A programme that will investigate vaccine boosters when it starts in June will be led by Prof Matthew Snape of the Health Research Authority, he confirmed.
Comedian Matthew Highton mocking up Van-Tam as if he was speaking in front of a Hogwarts lectern live on Sky News.
For a while Professor Snape trended on Twitter as others, including broadcasters, piled in.
Sky tweeted: “Jonathan Van-Tam says Professor Snape (not that one) will be running a study into which #COVID19 vaccines people can receive as boosters.”
Dr Neil Penter added: “How marvellous! #DowningStreetBriefing.”
Dave Sansom said: “Looking forward to Bradley Walsh laughing hysterically in a few years on The Chase when they ask who ran the UK Covid trials: A) Professor Snape; B) Dumbledore; C) Miss Trelawney.”
It was left to the Health Research Authority to reveal the real scientist is their very own Professor Matthew Snape - not the sinister villain played by the late actor Alan Rickman in the Harry Potter film series.