How’s the stock market doing?
My interpretation of the Efficient Markets Hypothesis is not that the stock market is always correct about interpreting news, it was that it is very fast at reading the news. E.g., if the headline in your daily newspaper is “Huge Study Proves iPhone Causes Lethal Brain Cancer,” and you think to yourself, “You know, I should get out my computer and sell my Apple stock,” well, you’re too late.
But in this case, the markets had all the news for about 7 weeks and just didn’t interpret the news correctly until about February 20 as being really bad.
From Nature on the big question of shutting the schools:
5 March 15:30 GMT — China study suggests children are as likely to be infected as adults
Children are just as likely to become infected with the new coronavirus as adults, finds one of the most detailed studies yet published on the spread of the virus, known as SARS-CoV-2. The analysis — based on data from Shenzhen in China — provides a partial answer to one of the most pressing questions surrounding the outbreak: the role of children.
Previous studies have suggested that kids are much less likely than other age groups to develop severe symptoms when infected by the coronavirus. But it was not clear whether this was because they weren’t getting infected or because they were fighting off the infection more effectively.
“Kids are just as likely to get infected and they’re not getting sick,” says Justin Lessler, an infectious-disease epidemiologist at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. He co-led the study with three other epidemiologists — Qifang Bi, also at Johns Hopkins, Ting Ma at the Harbin Institute of Technology in Shenzhen and Tiejian Feng at the Shenzhen Center for Disease Control and Prevention. They posted the analysis to the medRxiv preprint server on 4 March.
The study is unique in that it looked at not only people who were infected with the virus, but also large numbers of their close contacts, some of whom were infected and many of whom were not. The researchers followed 391 people who were diagnosed on the basis of their symptoms, and 1,286 of their close contacts to see whether these contacts tested positive for the virus even if they didn’t show symptoms. Overall, the team found that children under 10 who had potentially been exposed to the virus were just as likely to become infected as other age groups, with between 7% and 8% of contacts of known cases later testing positive.
The authors also found that people who lived in the same household as someone infected with the virus were about six times more likely get infected than those who made contact with an infected person in other settings.
“This may be the first clear evidence that children are as susceptible as adults to SARS-CoV-2 infection,” says Ben Cowling, an infectious-disease epidemiologist at the University of Hong Kong. He wonders whether the fact that outbreaks haven’t been observed in schools could be down to the fact that children’s symptoms are mild.
Lessler says it’s still not clear whether children are important in transmitting the virus, as they are for influenza; children routinely develop flu symptoms and are common hubs in chains of transmission.
If children aren’t very symptomatic, are they still spreading the infections?
“That’s one of the current critical remaining questions and we’re trying to figure out how to answer it,” he says. “I have a 7-month-old and a 6-year-old and I can’t imagine that, if they have any virus at all, they’re not getting it on somebody.”
The study could have important implications for slowing the spread of the virus through measures such as school closures. “Once we say containment is not an option, we can’t ignore the kids,” says Lessler.
“This is a key piece of data that may support school closures as an effective intervention,” Caitlin Rivers, an epidemiologist at Johns Hopkins Bloomberg School of Public Health, said in a tweet on 5 March.