Are you a key worker who needs to travel on public transport into work? If the answer to that question is 'no', then study the image above. It's a detailed diagram of the tube map you'll be using until social distancing is over.
That's right there's absolutely no tube line you should be taking. Same goes for the Overground, DLR and trams too. This curt image from Geoff Marshall is a reminder of that.
Lots of images have emerged online of the tube being nearly as crowded as any other day. However, while some rogue businesses are remaining open forcing staff to travel, most crowding is likely due to the fact that key workers — NHS staff, supermarket employees, etc. — are being forced to use a severely limited number of services.
The Mayor of London has said that because of the numbers of staff who are sick or self-isolating (and this number continues to grow), TfL cannot up the number of services it's running. Which is why it is especially vital that people who are not key workers avoid public transport like the plague. Because... of the plague.