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As the coronavirus comes to Boston we’re facing an important barrier to containment. Surprising as it may sound, Americans have a hard time accepting the germ theory of disease — that transmissible microorganisms cause illness. But the choices we make about where we go and who we visit will have a big influence on who becomes infected.

Here’s a common scenario that leads to problems. The kids are sick, the parents need a break, and the grandparents live close by and don’t mind babysitting. That’s great, right? No — WRONG! Back when I had preschoolers, colleagues and I authored a paper in the medical literature showing that 3- and 4-year-olds are among the first to get the flu. In fact, they often give it to adults (as any parent with a child in day care knows).


The bad news is that spikes in flu rates among the under-5 population are a clear signal of impending mortality in the elderly. In other words, the elderly die, in part, because flu incubates among day care and school populations and then spreads through the age groups. Few if any children have become very sick with Covid-19, the illness caused by the new coronavirus, but it is reasonable to assume that, as with other viruses, they can be infected and will pass it on to grandma and grandpa.

In 2006, the Centers for Disease Control and Prevention changed its recommendation on the flu vaccination to include younger age groups, a change made partly on evidence presented in the paper I co-authored.

But I also took another lesson from the research. Whenever my own kids were sick, I kept them away from my parents and other elderly folks. I think it helped.

It is also worth being introspective about what it means to bring a child into school or day care sick. While most schools implement plans to avoid exposure of allergic children to triggering foods, few protect vulnerable children from communicable disease. Even children who are not vulnerable themselves contribute substantially to societal spread when infected.


The global crisis around the spread of the coronavirus forces us to re-examine our attitudes and behaviors toward communicable disease. Recently, very early on in the coronavirus epidemic, a colleague and I were the first to show that each infected person will likely infect two to three more. However, because laboratory testing is so limited, we know little about the overall number of cases or the mortality rate. We do know, though, that the elderly are disproportionately at risk of dying from the virus.

It is the responsibility of each person and each family to act as if preventing disease transmission really matters. Don’t go to work sick. Don’t send your sick children to school or to visit with the elderly. And if you’re an older person yourself, stay at home as much as possible.

Dr. Ken Mandl directs the Computational Health Informatics Program at Boston Children’s Hospital and is the Donald A.B. Lindberg Professor of Pediatrics and Biomedical Informatics at Harvard Medical School. Follow him on Twitter @mandl

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