Investing in prevention—through vaccines, education, and family support—may cost now but yields lifelong benefits in health, education, and income
Anyone who has raised young children knows the story: the toddler comes home from daycare with a runny nose, and soon the baby is coughing too. Our research shows that this common experience is more than a minor inconvenience. It can have long-lasting effects on younger siblings’ health, education, and even adult earnings.
Using nearly forty years of Danish population data, we find in our recent IZA Discussion Paper that second-born children are two to three times more likely to be hospitalized for respiratory infections during their first year of life compared to first-born children. This gap is particularly large in the first months of life, a critical period for brain and lung development.
The reason is straightforward: older children often bring home viruses such as Respiratory Syncytial Virus (RSV) or flu from daycare or school. While these infections are usually mild for toddlers and adults, they can be dangerous for infants. By comparing siblings and linking their outcomes to community-level variation in disease outbreaks, we show that early-life exposure to respiratory illness has significant causal effects.
Younger siblings exposed to more circulating viruses in their first year of life are more likely to be hospitalized as infants and fare worse later in life. As adults, they earn less, are less likely to complete high school or college, and are more prone to chronic respiratory conditions like asthma and Chronic Obstructive Pulmonary Disease. They also use mental health services more frequently as teenagers and young adults.
How large are these effects? Moving from a low-disease community to a high-disease community during the first year of life reduces adult earnings by about as much as a 10 percent drop in birth weight or being born during a year with unusually high air pollution. The harm is concentrated in the first six months of life, highlighting the extreme vulnerability of this period.
Our findings suggest several policy implications: First, public health campaigns should inform parents about ways to reduce household transmission of illness, such as handwashing, mask use during illness, and limiting contact between sick toddlers and infants when possible. Secondly, vaccines and antibody treatments are key. New RSV vaccines given during pregnancy protect newborns, while monoclonal antibody treatments given to infants reduce RSV hospitalizations by more than 80 percent. Thirdly, targeted interventions are crucial: since risk is highest in winter and with closely spaced births, outreach should focus on families with multiple young children, especially those with infants during winter months. And finally, breastfeeding support can help: we find breastfeeding in the first six months offers protection, so policies like paid parental leave and workplace accommodations can reduce severe illness risk.
These results remind us that childhood colds and coughs carry hidden, long-term costs. They affect not just family well-being but also education systems, labor markets, and healthcare budgets decades later. Yet most cost-benefit analyses of vaccination and childcare policies ignore these broader impacts.
Investing in prevention, through vaccination campaigns, education, and family support, may seem costly now, but it pays lifelong dividends by improving health, educational attainment, and earnings. Families cannot stop older children from catching viruses, but we can act to protect infants at the most vulnerable stage of life. Recognizing that “family germs” are more than a passing nuisance is a first step toward healthier, more prosperous generations.
© N. Meltem Daysal, Hui Ding, Maya Rossin-Slater, and Hannes Schwandt
N. Meltem Daysal is Associate Professor at University of Copenhagen, Denmark, and IZA Research Fellow
Hui Ding is Assistant Professor at the School of Economics, Fudan University, China.
Maya Rossin-Slater is Associate Professor at Stanford University School of Medicine, US, and IZA Research Fellow
Hannes Schwandt is Associate Professor at Northwestern University, US, and IZA Research Fellow
Please note:
We recognize that IZA World of Labor articles may prompt discussion and possibly controversy. Opinion pieces, such as the one above, capture ideas and debates concisely, and anchor them with real-world examples. Opinions stated here do not necessarily reflect those of the IZA.
Related IZA World of Labor content:
https://wol.iza.org/articles/early-life-medical-care-and-human-capital-accumulation by N. Meltem Daysal and Jonas Cuzulan Hirani
https://wol.iza.org/articles/childcare-choices-and-child-development by Daniela Del Boca
https://wol.iza.org/articles/is-maternal-employment-related-to-childhood-obesity by Wencke Gwozdz
Photo by Kelly Sikkema on Unsplash