So my wife, son, mum, dad have all tested negative. Which I’m delighted about. But also confused. I can’t think how my son who shoves his hands in my mouth, and my wife who I share a bed with haven’t got it!
Yeah, it's a weird one. It's a very contagious virus, but most people aren't very contagious. It's easier to think about as two series of coin flips.
The first one is "am I one of the contagious ones?" and if you flipped a coin 10 times, you'd only expect to see "yes" 2 or 3 times. Then you have very low odds of passing it onto anyone else even if you're with that person in the riskiests conditions for transmission. So for an individual the odds aren't bad. But those 2 or 3 times really matter for a wider population, because the odds flip for the next question.
If you are one of the contagious ones, then the answer to "will I pass it onto this person?" will be "yes" about 7 or 8 times out of 10, and if it's indoors, with poor ventilation and with lots of close contact, it's close to 10 out of 10. So those people that are contagious spread it to quite a lot of people, they might only be 2 of every 10, but they make up for it by passing it onto plenty more.
A lot of the coronaviruses that cause the common cold work in the exact opposite way, which is how we think about viruses. Most people are contagious, but no so contagious that they'll pass it onto most people that they'll meet. If you meet enough people, you'll probably pass it onto one or two of them, but you're very unlikely to pass it onto the group, and you're also very unlikely to pass it onto no-one. This one is more about the extremes. Which is why people worry about pubs and stuff, even with the precautions.