Daglige smittetal er misvisende i forhold til smittespredning i en befolkning.
Corona in the United States: 120 million Americans have had covid-19
New research provides insight into the spread of infection in the American population.
»It is so easy here in Denmark to get a lightning test. I took one yesterday, and so did our friends, so tomorrow we can meet for dinner, “my Danish friend said happily. We exchanged social lives – or lack thereof – over the phone, she from Frederiksberg, I from Seattle.
I was told that for the first time in months we had met a neighbor a few blocks away. They had opened their garage, so there we sat under a heat lamp with electric blankets around us, while we gently occasionally lifted the masks as we took a sip of our brought beer. It was an absolutely amazing hour , even though we don’t actually know the neighbors who invited us very well. And even though we mostly talked about renovations of backyards.
But being with people you don’t live with, out in the real world, set some happy vibrations in motion in me. You forget how much socializing means when you have not had it for a long time.
The conversation with my Danish friend made me think about how we act in our new corona universe , and what is the basis for the decisions we make personally and the decisions the politicians make for us.
Like so many others, I regularly check the new infection rates. The question has been: How many have tested positive for covid-19 today? But that number only tells us about new cases, it does not say anything about how many people are still infected and can spread the disease.
A research team at Columbia University has created a calculation model that provides more accurate numbers than those we have dealt with so far. The researchers have come to the conclusion that the real number of active infected people who are still infected is 10 times higher than the daily infection rate. That in itself is not surprising. We know that there are a far greater number of covid-19 positives in a population than those who are tested positive.
The interesting thing is that we are now so far into the course of the pandemic that research is able to verify that the forecasts that have been loosely expressed actually seem to hold true. Research estimates that 120 million Americans have had covid-19.
Why is it interesting at all? It is because it influences our day-to-day decisions as individuals and the decisions of politicians on behalf of the people.
Our decisions depend on the knowledge available on whether the disease is spreading in the population. As individuals, many of us use the daily infection rates to consider our behaviors, e.g. whether we feel we can safely go for a walk on the street, in the park or down in Netto without fear of being infected.
At a more general political level, the infection rates guide considerations of curfew and vaccine strategy.
The Columbia research team has created a mathematical model that asks the question: For every positive test on a specific day – how many actually become contagious on that exact day?
People are contagious for three to four days, so if I am spoken to in the positive tests on Monday, I am still contagious on Tuesday, Wednesday and maybe even Thursday. Therefore, the number of days does not say enough, and you have to count every single positively tested person as a carrier for more than one day. At the same time, the large number who are not tested, but walk around and are positive, must be included.
Here in the United States, this concretely means that 1.25 million Americans right now, today, are infected and thus able to pass on the infection. The figure is lower than when it was at its highest, which analysts believe has to do with the fact that many Americans have already had covid-19. In the state of North Dakota, it is estimated that 51 percent. of the population have had the virus. Nationwide, researchers from Columbia estimate that approx. 120 mio. Americans have had the virus – it’s just over a third of the population.
So what? When they here in the United States say that you should behave as if everyone you meet on your way when you leave your house has a corona , then it’s not just disaster talk. For apparently it is actually the case that I should not have passed quite a few on my way before one of them is infected.
For me, this means that in the short run I have been confirmed that I do the right thing when my social life is limited to a maximum of one hour together behind the mask in a garage on a folding chair with a heating blanket around me. On the slightly longer course, I think the earliest I can meet for an indoor dinner with my beautiful Danish friend in the autumn. Until then, our social gatherings must continue to take place behind our screens.