Publications
Race, immunity, and lifespan: Unraveling the effect of early-life exposure to malaria risk on lifespan
Economics and Human Biology, 54, 101382. 2024. (with Sok Chul Hong) [Link]
Abstract
We investigate a historical experience to measure the long-term effect of malaria on lifespan among infected survivors and identify a factor that mitigates malaria’s effect. Using a sample of Union Army veterans born during the mid-19th century and their lifetime records, we show that exposure to high risk of malaria at birth or in early life substantially shortened their lifespan. The legacy of exposure to malaria is robust while controlling for lifetime socioeconomic and health conditions, fixed effects, and considering selection bias. Additionally, we include the US Colored Troops sample of black veterans to analyze racial differences in the effect of malaria exposure on lifespan. Exposure to malaria did not lead to a shorter lifespan among black veterans. Evidence suggests that genetic immunity to malaria in black veterans might contribute this heterogeneity.Mortality, Nutrition and Height in Early Colonial Korea
Review of Economic History, 67(2), 197–225. 2018. (in Korean) [Link]
Abstract
The determinants of stature can be changed in one country by the change of cultural and economic situation. The cases of western countries in 19th century are good example. Therefore, identifying the determinants is needed to understand the change of stature in colonial Korea. In this study, I used Prisoners’ cards made in prions that provide a lot of information about their characteristic. What I found is that disease environments were important factors to determine people’ stature in early colonial Korea. The change of the mortality rate that reflected disease environment explained the statural change. I analyzed influence of disease environment by year. There is no difference in the coefficient by year. The implication of this study is to identify factor determining statures in early colonial Korea.Working Papers
(Job market paper) Avoiding the Risk, Bearing the Cost: Evidence from General Health Screening in Korea during the COVID-19 Pandemic
submitted (with Sok Chul Hong) [PDF]
Abstract
This study examines the unintended health consequences of voluntary responses to COVID-19. We focus on general health screening in Korea, using administrative data that link medical claims and screening records. At the national level, screening rates declined markedly in 2020, the first year of the pandemic, relative to counterfactual trends. Complementing this aggregate pattern, individual-level analysis reveals notable heterogeneity: declines were larger among those with higher predicted risk of chronic disease. We then assess the consequences of forgone screening, employing propensity score matching and event study designs. Our estimates show that, had they been screened, individuals who missed screening would have been more likely to initiate care for chronic diseases. The costs of missed screening were especially large among those at higher predicted risk of chronic disease. Such delays in management led to more advanced conditions at the time of care initiation. Our findings show that, even without strict quarantine policies, voluntary responses to infection can undermine preventive care, disproportionately affecting high-benefit groups. This underscores the importance of balancing infection control with the continuity of preventive care during health crises.The National Immunization Program for Children Expanded: Its Impact on Influenza Vaccination and Healthcare Use
[PDF]
Abstract
This study examines the impact of expanding the eligible age for child influenza vaccinations in Korea. To control for time trends in influenza vaccination rates, I estimate a difference-in-differences model using children not affected by the age expansion as a control group. Through this model, I find that expanding the program's eligible age significantly increased the vaccination rate of children aged 5-12 in the treatment group. This increase is mainly observed among households with incomes above the median, those with working mothers, and those living in areas with high access to healthcare facilities. Next, I use National Health Information Database from the National Health Insurance Service (NHIS) to analyze changes in influenza-related healthcare utilization as the program's eligible age expanded. The results show that the estimates from the difference-in-differences model are not robust to time-varying confounding factors related to influenza incidence. To address this, I estimate a triple difference model that exploits temporal variation in the match between the influenza vaccine and prevalent viruses. The results show that influenza-related healthcare utilization decreased during periods of high match rates after the policy was implemented.Works in Progress
Negative Vaccine Information and Adverse Event after COVID-19 Vaccination: Evidence from the Official Recognition of Causality in Korea
(with Sangbeom Kim, Dae-il Kim, Sok Chul Hong)
Abstract
Information plays a crucial role in shaping vaccine-related behaviors. However, because the timing of exposure to vaccine information can trigger responses at different margins, focusing solely on vaccination uptake risks underestimating the overall effect of information. We exploit a major information shock—the Korean government’s recognition of a causal link between the Pfizer-BioNTech vaccine and myocarditis/pericarditis—to investigate its impact on healthcare utilization after vaccination. Using the K-COV-N cohort, an administrative dataset linking vaccination records and health insurance claims, we implement a difference-in-differences framework comparing individuals vaccinated around the announcement with not-yet-vaccinated controls. We find that exposure to the announcement increased adverse event–related healthcare utilization by about one percentage point from a 4.5% baseline. The increase was concentrated in general adverse events such as headache, fever, and muscle pain. Effects were most pronounced in clinics, suggesting precautionary care-seeking rather than acute health deterioration. These results indicate that, in a context of high vaccine uptake, negative vaccine information primarily reshapes post-vaccination risk perception, highlighting the importance of considering the costs of transparency in vaccine risk communication.The Impact of Wedding Restrictions on Non-Marital Births during COVID-19: Evidence from South Korea
(with Dae-il Kim, Sok Chul Hong)