Comments from UK leading medical officials
The UK's chief medical officer and the NHS England medical director say there is a material risk the health system in several areas is overwhelmed in the next 21 days. Both recommend raising the national alert level to 5.
That would mean schools are closed and that bubbles are narrowed along with more stores closing.
Johnson is set to speak in just under 2 hours and many reports say he will announce more stringent measures.
