Michael Nagle / Xinhua News Agency / Getty Images
Within weeks of reopening parts of the United States, coronavirus infections are on the rise in several states, including Arizona, Utah, Texas and Florida. Dramatic increases in the number of daily cases have raised troubling questions: is the United States at the start of a second wave? Have the states reopened too early? And did the recent widespread protests against racial injustice unintentionally fuel the fire?
The short and unpleasant answer to the first question is that the United States has not even overcome the current first wave of infections. Since peaking at around 31,000 new cases per day on March 10, daily cases fell to around 22,000 new cases on average in mid-May and have remained almost stable over the past four weeks. Across the country, more than 800 people continue to die day after day.
Leading forecasters predict a slow but steady buildup of additional deaths by October 1 – an estimated 56,000, about 90,000 of them.
“We really never really finished the first wave,” says Dr. Ashish Jha, professor of global health at Harvard University. “And it doesn’t seem like we’re going there anytime soon.” ”
That said, forecasters say we may still be expected for a real second wave later in the year, citing growing evidence that colder weather could lead to more coronavirus cases.
Why we are stuck
So why is the United States stuck in a coronavirus platter despite months of widespread social distancing? To explain, it helps to get a little technical. The key indicator at issue is what is known as the coronavirus ‘breeding number’ – or R for short – essentially an indicator of the strength of the spread of the infection in your community. It tells you, for each person infected, how many other people that person will continue to infect. When the number of reproductions is greater than 1, the number of cases will increase exponentially. When it gets well below 1 and stays there, the epidemics subside.
For example, if the number of reproduction is 2, then one person continues to infect two others. These two people infect four others. These four then infect eight, then 16 and so on. If you assume, say, a six-day interval between each new round of infections – in just over a month, that a first person will have launched a chain that has infected 127 people.
Most estimates indicate that at the beginning of this year, when no action was taken to control the coronavirus, the number of spawners in the United States was above 2.
The home support measures and other social distancing efforts that the states have undertaken this spring have reduced the number of spawners slightly below 1 – to 0.91, according to an estimate by Youyang Gu, a Independent modeller whose work is highly appreciated by leading epidemiologists. .
This stopped the upward spiral of cases. But since the number of reproductions was still so close to 1, the curve of new infections never really fell back down. In essence, most of the United States has reached some sort of stable state – each infected person transmitting the virus to a new person in a regular drip of new infections and new deaths.
“If things remain basically the status quo and we continue to do what we do, we will continue to see an additional 25,000 to 30,000 deaths per month for the foreseeable future,” said Jha.
Now that the states have opened, the number of reproductions has started to rise above 1. According to Gu’s analysis, this is the case in more than two-thirds of the states. Assuming the number of reproductions remains around 1, the United States is unlikely to see the kind of fugue in such alarming cases in New York. But that means that cases and deaths will continue to increase steadily.
Tony Gutierrez / AP
As dark as it is, even this image may be too pink, says Jha. “I’m afraid the idea of staying flat all summer is a very optimistic view of what’s going to happen over the next three months,” he said.
To keep a reproduction number close to 1, or better yet, reduce it to just under 1 “, it would take a lot of work,” says Jha. “The tests and the isolation should be considerably increased [of new cases]. “There is also evidence emerging that widespread use of masks by people when in public may help,” notes Jha. Unfortunately, he said, it is difficult to imagine that the United States will adopt one of these practices to a sufficient degree “depending on where we are today. ”
The seasonal effect
It’s getting worse. Chris Murray, head of the forecast team at the University of Washington Institute of Metrology and Health Assessment, said on Thursday that there is mounting evidence that coronavirus will spread more easily when time cools.
Murray’s team has analyzed the spread of coronavirus in the United States to date. They found that the decline in the number of spawners since early spring cannot be fully explained by obvious contributing factors – such as reduced mobility of people or wearing masks or better tests. And when the team looked for additional variables that could explain the change, they found a strong correlation with global warming.
This finding does not shed light on Why transmission can be reduced during the warmer months. (For example, could it be that the coronavirus droplets don’t stay as long in the cold air? Is it just that people spend less time mixing inside indoors?) But Murray says that “over time, there is mounting evidence that this is a very good predictor of transmission. ”
The effect is not strong enough to completely wipe out the virus over the summer. But that means, says Murray, that fall transmission will likely resume.
“If he follows the historical pattern of pneumonia, then [right now] we can be in a period in most states of the United States with relatively low numbers, low transmission, but worrisome trends in the wrong direction in September and October. “Murray says. Seasonality will be a big driver of the second wave. ”
Alex Edelman / AFP via Getty Images
However, he adds that this does not take into account actions likely to mitigate the impact. “Obviously, what individuals choose to do can moderate expectations,” he said, noting that widespread use of the mask and lack of social contact with people outside the home could help.
Analyze the effects of protests
While many public health experts have applauded the anti-racism protests – and the possibility that many lives may ultimately be saved if the protests lead to policy changes that reduce racial inequality – some have wondered to what extent this would result in an increased cost of COVID -19 deaths.
But it’s difficult to calculate the number of additional infections that the protests could cause. There is no precise count available of the number of participants, let alone their age – which seem to distort young people, suggesting that the vast majority of those infected would not experience poor outcomes.
In addition, with little previous research on this particular form of the mixture, it is difficult to say how much infection results. Although many people stand and walk in tight quarters, being outside alleviates the effect of overcrowding, as does the use of the mask.
“Some transmissions will almost certainly occur during protests, and the question is whether they result in a large number of downstream cases or a relatively small number of downstream cases,” said Marc Lipsitch, epidemiologist at Harvard.
What really matters, he explains, is what’s going on after events. Do those infected during walks go into an environment where there is a high level of continuous transmission or a low level?
“The amount of transmission that occurs later,” says Lipsitch, “depends much more on our actions as a society and the ability to stop transmission across the country than on the number of people who go to the protests. ”
In other words, the best question may not be: will the protesters cause an increase in COVID-19 infections? Rather, all of us – the public and our leaders – will behave in such a way as to maintain a low number of breeders and to ensure that these marches and any improvements in racial equality they achieve do not lead to many deaths. COVID-19 additional.