Last week, my daughter, a freshman at a Midwestern university, was informed that the spring quarter would be replaced by a remotely conducted quarter. Hundreds of other schools have canceled what remained of their semesters. And there is a long and expanding list of canceled conferences, concerts, shows, parades, and even professional sports leagues. The cause is a new disease, COVID-19, caused by a new virus, SARS-CoV-2. At the moment, it is hard to know whether these responses are warranted. How many people are infected and how many of them will die remain unknown. But enough is known to suggest that fear of the unknown, risk aversion, and acute anxiety are influencing these actions.
COVID-19 was first identified in China in December 2019. The number of cases in China rose rapidly toward 80,000 but, per Chinese-government figures, stabilized by the end of February. The number of new cases began to fall in response to draconian public-health measures, including aggressive identification and isolation of cases and their contacts, quarantines of large cities, and travel restrictions. A similar pattern unfolded in South Korea, which identified its first case on January 20, had an initial rapid rise in cases, and now, following an aggressive program of testing and isolating cases, has seen its number of new cases fall rapidly. Now Europe (especially Italy), Iran, and the U.S. are in the expansion phase. The first U.S. case, a 35-year-old man who had returned from China five days earlier, presented on January 20. As of March 20, 2020, there are about 14,000 reported cases in the U.S. and about 215,000 confirmed COVID-19 cases worldwide. The World Health Organization (WHO) officially declared a worldwide pandemic on March 11.
How scared should we be of COVID-19? The answer depends on determining how many people are actually infected and what the case fatality rate — the number of deaths from the disease divided by the number of diagnosed cases — is. The COVID-19 virus appears to be readily transmissible between people. But determining the number of cases is difficult because the typical COVID-19 symptoms — cough, fever, fatigue — are similar to other illnesses, such as the flu, that are prevalent this time of year. Moreover, 80 percent of cases have only mild to moderate symptoms and do not attract medical attention. Even in South Korea, which has the world’s most aggressive testing regime, only a small fraction of the population has undergone laboratory testing for the virus. Deaths from COVID-19 (the numerator) are far easier to count than cases (the denominator). If the number of cases in the denominator is too low, the case–fatality ratio will be too high.
While early estimates of the COVID-19 fatality rate were quite high, a recent Chinese report put the fatality rate at 1.4 percent of hospitalized patients. These are more severely ill than the general patient who is not sick enough to be hospitalized or even need medical attention, so the number for all patients should be lower. The latest fatality estimate from South Korea is 0.9 percent. But this too is likely to fall as the outbreak evolves and a more accurate account of Korean cases is obtained. That is the usual pattern in epidemic infections. In the 2009 H1N1 pandemic influenza outbreak, for instance, the initial case–fatality estimate was 1 percent. As time passed and we obtained a more accurate case count, the U.S. rate fell to 0.02 percent. At this still early stage of the pandemic, uncertainty remains. The fatality rates in Italy and Japan, both countries with elderly populations, are reported to be near 8 percent and 3 percent, respectively. Germany, in contrast, has a rate of 0.2 percent.
Read the full article at National Review.