摘要：Objectives. We examined the association between influenza outbreaks in 83 metropolitan areas and credit card and mortgage defaults, as measured in quarterly zip code–level credit data over the period of 2004 to 2012. Methods. We used ordinary least squares, fixed effects, and 2-stage least squares instrumental variables regression strategies to examine the relationship between influenza-related Google searches and 30-, 60-, and 90-day credit card and mortgage delinquency rates. Results. We found that a proxy for influenza outbreaks is associated with a small but statistically significant increase in credit card and mortgage default rates, net of other factors. These effects are largest for 90-day defaults, suggesting that influenza outbreaks have a disproportionate impact on vulnerable borrowers who are already behind on their payments. Conclusions. Overall, it appears there is a relationship between exogenous health shocks (such as influenza) and credit default. The results suggest that consumer finances could benefit from policies that aim to reduce the financial shocks of illness, particularly for vulnerable borrowers. Seasonal influenza is a viral airborne disease that generally spreads each fall and winter, causing an estimated 1.5 million people to get sick and 200 000 to be hospitalized in a typical year in the United States. 1,2 Symptoms can range from mild and hardly distinguishable from a common cold to severe and life-threatening. Influenza accounts for at least 500 000 deaths in the United States in the past 3 decades. 3 For employed individuals, influenza can make attending work difficult, because of either personal illness or caring for sick household members. This generates significant costs to employers and employees. Estimates from 2007 suggest that annual influenza outbreaks lead to $16.3 billion in lost productivity and wages, and $10.4 billion in medical costs, 4 although these costs vary considerably across place. 5 Although there is a robust literature on the economic costs of influenza, we know little about how such unexpected health shocks are associated with other aspects of the economy, such as loan defaults. We built on existing knowledge of the economic costs of influenza by examining how influenza outbreaks influence credit card and mortgage default rates in US cities. In the wake of the Great Recession, loan defaults have increased, with negative financial consequences for families. 6 For loans due on a monthly basis, such as mortgages and credit cards, past-due balances and late fees accumulate each month. Three missed payments (90-day delinquent) is a signal of a loan at high risk for failure and in most states triggers legal collections processes. 7 In the microeconomic literature, illness is seen as a shock—an unexpected event—that can affect household income and expenses. If the shock results in a disruption to income, households will respond with shifts in consumption and expenditure patterns. 8 We contend that influenza, as a health shock, has the potential to trigger loan default by constraining a family’s budget because of personal illness or caretaking burdens. Influenza may also trigger inattention to household financial management and a lack of planning for future bill payments. 9–11 This may be especially problematic for borrowers who are already behind on their payments, whom we define as vulnerable borrowers. For these borrowers, who also tend to be economically vulnerable and disadvantaged in other ways, 12,13 an influenza outbreak could increase the likelihood of further missed payments. A recent study supports this notion, and shows that economically vulnerable households are more likely to borrow and borrow more in the event of a health shock than less vulnerable households. 14 However, this study did not examine credit default. A growing literature examines the complex and potentially multidirectional relationship between health and default. 15–19 Most research examines whether defaults influence health, 15,19,20 and less examines how health may have an impact on default risk. 21 However, a key problem inherent in this literature is that health status is endogenous, and it is difficult if not impossible to disentangle processes of causation, selection, and reverse causation with survey data. Our interest in influenza provides us with a unique opportunity to improve causal estimates of health shocks on default. Influenza occurs to varying degrees in every city and year in the United States, and the intensity of the outbreak is an ostensibly exogenous health shock for communities. Thus, influenza outbreaks provide a natural experiment in which we use variation in influenza severity across time and place to identify the effects of a particular health shock on default. Specifically, we ask whether influenza outbreaks in US metropolitan statistical areas (MSAs) are associated with defaults from the first quarter (March) of 2004 (Q1 2004) to the second quarter (June) of 2012 (Q2 2012). We make 3 contributions with this study. First, we extended the literature on the economic costs of influenza. Second, we contributed to the literature on health shocks and default by providing a stronger test of the potential causal impacts of health shocks on loan default. Third, we considered whether effects vary across types of default, including 30-, 60-, and 90-day defaults. We predicted that influenza may have the greatest effect on borrowers who are already in default, such that the association between influenza and default should be stronger for borrowers who are farther behind.
