The notorious track and trace system has instructed the Prime Minister to self-isolate for a fortnight.
Mr Johnson has informed us that he feels as "fit as a butcher's dog" and "bursting with antibodies." Antibodies which, one imagines should protect him against another bout of the virus. He was admitted to intensive care seven months ago, so it is likely he is now immune.
Although it is possible that BoJo could catch it for a second time, the odds are miniscule. Out of 55 million cases globally, there have been just 10 confirmed cases of reinfection.
If Boris has to isolate even though he has recovered from COVID previously, what is the point of the vaccines over which there has been so much excitement?
Remember that these self isolation rules are the law. A peculiarity - to say the least - of this law is that people must remain at home for 14 days even if they test negative. He must stay away from Carrie Symonds and his baby for the full fortnight.
By way of contrast those who think they have virus symptoms, and isolate while awaiting test results, are allowed out immediately if it turns out they are not infected.
Those who test positive have to isolate for ten days.
Q.E.D. People who have the virus need to stay inside for less time than people who test and trace thought might have it but turned out not to.