How many people in the UK have Covid-19?
Such a simple question, but one for which we haven’t had an answer - until now.
The Office for National Statistics (ONS) has just published preliminary results from its survey of Covid-19 infection in a random sample of English households.
They’ve sampled 7,087 individuals so far and estimate that just 0.24% of the population have Covid-19.
Equivalent to 136,000 people in England.
They used a test that only detects the presence of the virus, not antibodies to it - so it only tells us how many people have an active, or very recent infection.
But it remains the first snap-shot we’ve had.
Compared to the estimated infection rate in some healthcare workers of between one and three per cent it seems very low.
Suggesting, perhaps not surprisingly, that transmission of the virus in hospitals and care homes is higher than in the wider community.
But the new information is crucial for informing the government's lockdown response.
First, the calculation of the “R” number, now so beloved of the government, which describes the reproductive rate of the outbreak.
So far, calculations of R have been based on data from hospital testing.
But that only gives you information on people getting sick with the virus.
It’s not certain that that is giving us a true picture of R.
What’s also been missing in terms of calculating how likely we are to see a second wave, or not - how many people actually have actually the virus.
Despite the furore over testing, the grim death-toll in care homes, or access to PPE, this staggeringly obvious, this important question is finally getting answered.
We’re expecting more details from the ONS on Thursday.
Coronavirus: Everything you need to know