Understanding COVID-19 Vaccine Effectiveness Against Death Using a Novel Measure: COVID Excess Mortality Percentage (preprint)

COVID-19 vaccines have saved millions of lives and prevented countless adverse patient disease outcomes. Understanding the long-term effectiveness of these vaccines is imperative to developing recommendations for precautions and booster doses. Comparisons between more and less vaccinated groups may be misleading due to selection bias, as these groups may differ in underlying health status and thus risk of adverse COVID-19 outcomes. We study all adult deaths over April 1, 2021-June 30, 2022 in Milwaukee County, Wisconsin, linked to vaccination records, use mortality from other natural causes to proxy for underlying health, and report relative COVID-19 mortality risk (RMR) for vaccinees versus the unvaccinated, using a novel outcome measure that controls for selection effects. This measure, COVID Excess Mortality Percentage (CEMP) uses the non-COVID natural mortality rate (Non-Covid-NMR) as a measure of population risk of COVID mortality without vaccination. We validate this measure during the pre-vaccine period (r = 0.97) and demonstrate that selection effects are large, with Non-Covid-NMRs for two-dose vaccinees less than half those for the unvaccinated, and Non-COVID NMRs still lower for three dose (booster) recipients. Progressive waning of two-dose effectiveness is observed, with relative mortality risk (RMR) for two-dose vaccinees aged 60 + versus the unvaccinated of 11% during April-June 2021, rising steadily to 36% during the Omicron period (January-June, 2022). Notably, a booster dose reduced RMR to 10–11% for ages 60+. Boosters thus provide important additional protection against mortality.

Appendix for The COVID-19 Pandemic and Life Expectancy: Decomposition Using Individual-Level Mortality Data (preprint)

This Appendix provides methodology details and additional results for Barreto Parra, Atanasov, Meurer, Whittle, Luo, Zhang, and Black, The COVID-19 Pandemic and Life Expectancy: Decomposition Using Individual-Level Mortality Data (working paper 2021). The underlying paper is available from SSRN at https://ssrn.com/abstract=3795801.

The COVID-19 Pandemic and Life Expectancy: Decomposition Using Individual-Level Mortality Data (preprint)

We develop cohort-based estimates of life expectancy without COVID, the fraction of persons who have died of COVID (population fatality rate, or PFR), and life expectancy loss, relying on individual-level data for three areas in the Midwestern U.S. (Cook County, Illinois; Milwaukee County, Wisconsin; and the State of Indiana). We use the individual-level data to assess how estimates of PFR and life-expectancy loss vary with age, gender, race/ethnicity, and socio-economic status. COVID PFR over March 2020-June 2021 for the three Midwest areas is 0.17% and decedents lose about 12 expected life-years. Life expectancy loss (LEL) is 0.17% * 12 years = 0.021 years (8 days); but can be as high as 3 months for some persons. Mean LEL is higher for men (0.025 years) than for women (0.018 years), and substantially higher for Blacks and Hispanic (0.030 years) than for Whites (0.018 years). We also provide national estimates using aggregate data. Life expectancy losses due to COVID exceed the annual gains in life expectancy over 2008-2018 for persons above ages 62-69 (depending on gender and race/ethnicity). Socio-economic status has modest incremental effect on life expectancy loss, relative to age, gender, and race/ethnicity. Our life expectancy loss estimates are much lower than published estimates which use a “period life expectancy” approach.

Data and Methodology Documentation for a COVID-19 Risk Calculator: Mortality Rates and Loss of Life Expectancy (preprint)

We develop careful cohort-based estimates of median life expectancy without COVID, COVID population fatality rates (PFRs) for three areas (Cook County, Illinois; Milwaukee County, Wisconsin, and the State of Indiana), and expected life expectancy lost due to COVID. We examine how PFR and lost life expectancy vary with age, gender, race/ethnicity, socio-economic status, and common comorbidities. On average, decedents lose about 12 expected life-years (upward biased estimate). Expected life lost to date for our three areas is around 0.016 years; an estimate for the whole U.S. population is 0.02 years (about one week) (upward biased estimates). Expected life lost rises rapidly with age and can be as high as 3 months for some individuals. Expected life lost for whites and Asians in our three areas is around 0.012, but is roughly double this for Blacks and Hispanics. We also provide data and methodology details underlying the COVID-19 Risk Calculator, available at https://fightcovidmilwaukee.org/risk-assessment-tool.

Economic Impact Payment, Human Mobility and the COVID-19 Mitigation in the United States (preprint)

This paper studies the relationship between the individual's income and COVID-19 mitigation effort contribution. The paper suggests that in addition to the government mandatory policies, the income compensation policy is an alternative government instrument that helps increase the individual and social aggregate COVID-19 mitigation effort. I empirically test the effect of the income compensation policy by utilizing the United States economic impact payment (EIP) in April 2020 as a quasi-natural experiment, and use the cellphone GPS measured human mobility data as the outcome indicator of the COVID-19 mitigation effort. I find that by receiving EIP, individuals on average significantly increase median home dwell time by 3%-5% (about 26-45 minutes). This paper highlights an unintended effect of EIP: in addition to providing economic assistance, EIP also helps mitigate the COVID-19 virus transmission.