The power of R

I’m trying to ration doomscrolling my Twitter feed nowadays to preserve my sanity; social media is truly appalling for mental health, but my brain occasionally replaces misery with shock or outrage. That’s what happened when I caught sight of a tweet reporting a briefing by Dr. Guido David of the OCTA Research Group.

According to Kristine Sabillo as reported on the ABS-CBN News Channel’s Twitter account: “David: The reproduction number (of COVID-19) has decreased slightly. It’s now at 1.9. There’s a reason to be a bit optimistic but 1.9 is still high reproduction number. It’s still close to 2.”

Eh? Here in the UK, it’s been drummed into us in countless briefings from the Prime Minister’s office, by the nation’s top scientists and health experts and other analysts interviewed on television, radio and websites that the “R number,” as they call it, should be less than one. My brain had snapped in a kind of cognitive whiplash – “a bit optimistic?” Surely this was a euphemism for “deeply disturbed?” Had the Philippine experts become more English than the English?

An R above one means an outbreak is growing, and below one means that it is shrinking. If the R number remains below one the disease will eventually stop spreading, because not enough new people are being infected to sustain the outbreak.

German Chancellor Angela Merkel explained it best. “We’re now at about reproduction factor one, so one person is infecting another one,” she said. “If we get to the point where everybody infects 1.1 people, then by October we will reach the capacity of our health system with the assumed number of intensive care beds. If we get to 1.2 people, so everyone is infecting 20 percent more, out of five people, one infects two and the rest one, then we will reach the limit of our health care system in July. And if it’s up to 1.3 people, then in June we will reach the limits of our health system. So that’s where you can see how little the margin is.”

Her genius was in realizing that numbers like 1.1 and 1.2 might not mean that much to people and explaining it in a more accessible way.

Here in the UK the rate of coronavirus infection – measured by the R number – is continuing to fall. The latest R estimate for the whole of the UK (from the government’s scientific advisory group Sage) is between 0.6 and 0.8.

It means that, on average and using Merkel’s way of explaining things: every 10 people with COVID will infect between six and eight other people. At its highest, the average R rate was 1.6 back in September.

(The R number is by no means the only measure by which to judge the severity of the situation in any country. In the UK the government has been using another two measures. First, severity – some people just get a mild form of the disease that does not cause many problems. But of course, coronavirus and the disease it causes, COVID-19, can be severe and deadly.

Third is the number of cases, which, we are told, officials here crucially use for deciding when to act. If you have a high number of cases, but then decide to ease restrictions so that the reproduction number reaches one, then you will continue to have a high number of cases.)

Another reason Merkel’s explanation was so accessible was that she put it in terms of the capacity of the German health care system. So I took a look at their hospital bed to population ratio (the number of beds to every 1000 people). In 2017 (according to the OECD website) in Germany it was 8. In the same year in the USA it was 2.87, while in Indonesia it was 1.04 and in the Philippines in the same year it was 0.99 (this number according to the World Bank). However in 2019, for the UK, it was 2.46. The World Health Organization recommends a minimum of 3 beds per 1000.

The thing is that all these numbers can be interpreted from different perspectives; the way you interpret the information is what makes it more or less important to the decisions you make. It also works the other way: you can tell how important someone thinks the situation is by the way they’ve interpreted the information.

I’m reminded of a conversation about human rights abuses I had with an English editor based in Southeast Asia. “This is just the way things are in X (fill in the name of a Southeast Asian country),” she argued, against making a story of something under discussion at the time. Was this a cause for optimism that it was so normalized that it was not newsworthy? Or was it deeply disturbing? Are some things, whether human rights or anything else, to be accepted in some places but not in others? Is it a matter of geography or history? Chemistry or biology?

I have never met Dr. David, and I certainly do not doubt his expertise in his field. Now more than ever, he and his colleagues must surely be taken seriously.

My issue is with his description of a 1.9 R number as “a bit optimistic,” if indeed that is what he said. I suspect that these words were used relative to the even worse situation that preceded them and that he probably misspoke.

An R rate of two means that for every 10 of the 5,290 new cases recorded by the Department of Health on Thursday March 18, another 20 people are being infected, who in turn are infecting another two, etc., creating enormous pressure on the health care system, the community and the economy. An R rate of 1.9 still means on average every 10 infected people is infecting another 19. That extra digit still signifies a person who could be any one of us. The coronavirus is viciously undiscerning.

Real lives are at stake. It is no exaggeration to say this is a perilous situation that must be brought under control.