Ok, R, what is it and why it's important, thread.

For the uninitiated, R0 is the basic reproduction number for a disease. This is basically how many people one infected person will go on, on average, to infect.

For instance, one child with measles can infect up to 18. Hence the importance of vaccination.

As long as R is above one, this means the number of infected persons will grow.

Eric who has COVID-19 might pass it onto Margaret from accounts, Sanjay who touched a handrail he touched, Susan his wife, and Bob who met him for a drink.

R here is 4

BUT if Margaret worked from home, Sanjay cycled or used hand sanitizer coming off the bus, and Bob told Eric to piss off, then the R falls to 1.

And if Susan sleeps in a different room, washes her hands all the time and stops Eric from germing up the city, R is even lower.

Hence the importance of ongoing social distancing measures. The lower R is, the faster we will reduce the threat of this spreading again.

There's going to be wild virus out there but as long as the R falls the number of infected people will decrease.

And that will stop the NHS from being overwhelmed, and it'll stop Sanjay from ending up on ICU, or Margaret passing it onto the elderly mother she lives with.

Staying at home if you can, maintaining distancing, hand hygiene, that's how we beat this.

The messaging from the Government needs to be clear, firms must be encouraged to have employees work from home.

People still must not congregate in large numbers.

Social distancing must still be maintained.

That is how we win, staying alert alone is not enough.