In a National Bureau of Economic Research (NBER) working paper posted Friday, MIT Economist Jeffrey E. Harris details how the data coming in from New York City indicates that “the coronavirus epidemic curve is already flattening” in the city — a development that has surprised many experts who predicted to see far worse numbers before things started to improve in the nation’s COVID-19 “epicenter.” If the trend is in fact legitimate, he asks, what exactly caused the number of new cases to level off? In the paper, he offers eight “alternative” explanations for the welcome apparent turning point, but ultimately suggests that none are fully satisfying answers.
“New York City has been rightly characterized as the epicenter of the coronavirus pandemic in the United States. Just one month after the first cases of coronavirus infection were reported in the city, the burden of infected individuals with serious complications of COVID-19 has already outstripped the capacity of many of the city’s hospitals,” Harris writes in the working paper’s abstract. “As in the case of most pandemics, scientists and public officials don’t have complete, accurate, real-time data on the path of new infections. Despite these data inadequacies, there already appears to be sufficient evidence to conclude that the curve in New York City is indeed flattening.”
Harris provides a chart (Figure 1) based on reports on total number of new infections by day from the New York City Department of Health that shows that around March 20, the day New York Gov. Andrew Cuomo issued his stay-at-home order, the number of new infections begins to flatten. The rapid flattening, Harris theorizes, may perhaps be partly accounted for, or at least problematized by, a combination of alternative explanations, including 1. supply constraints on testing, 2. undetected asymptomatic cases, 3. false negatives, 4. differing rates in different boroughs, 5. New Yorkers leaving the city, 6. an “unrealistic” initial upswing, 7. a large degree of infectivity in the city’s population, with a small percentage susceptible to “the super-spread of the virus,” and/or 8. a lack of supporting data that may demonstrate that the trend is not legitimate.
However, Harris appears skeptical that any of those possible explanations fully account for the clear flattening trend in the city. “[I]t is entirely possible that some of these alternative explanations are at least partially valid and that the epidemic curve in New York City is flattening,” he writes. “Based on the evidence reviewed here, however, it is difficult to dismiss out of hand the conclusion that the incidence of new coronavirus infections has indeed leveled off.”
After stressing that the leveling doesn’t necessarily mean the city has “reached its peak” on new cases, Harris provides some thoughts on how the curve was flattened so quickly, including that some social distancing measures implemented initially by Mayor Bill de Blasio a few days before the March 21 “leveling,” combined with people’s voluntary avoidance behaviors “once they fully perceive[d] the risks of contagion,” helped rapidly stem the tide of the disease. (Read the full analysis here.)
Harris’s analys of the numbers aligns with Gov. Cuomo’s statements over the last few days. The governor announced on Monday that the number of daily coronavirus deaths in his state has been “effectively flat for two days.” The number of hospitalizations and intensive care admissions, he explained, have hit their lowest points in more than two weeks. “While none of this is good news, the possible flattening of the curve is better than the increases that we have seen,” Cuomo said in reference to the latest report on fatalities. Though he highlighted the positive news, he also cautioned that we must not make the mistake of “underestimating” the “enemy.”
According to the most recent data from the New York City Department of Health, a vast majority of those who have died of the coronavirus had a serious underlying condition (including diabetes, lung disease, cancer, immunodeficiency, heart disease, hypertension, asthma, kidney disease, and GI/liver disease). The most recent data as of April 6, 9:30 a.m. shows that 65.6% of those who have died after testing positive have been confirmed to have one of those serious underlying conditions (1,623 out of 2,475), while the determinations on another 32.6% (807) of the victims are still pending. Only 1.9% (46) of those who have died and tested positive have been confirmed to have no underlying conditions.