How COVID’s spread in the home offers clues for public health response

Inder Singh
3 min readFeb 22, 2022
Proportion of household transmission, Kinsa

With states around the country lifting mask mandates, it is starting to seem like life is inching closer to “normal.” With the Omicron wave receding, more and more leaders are taking steps to transition from attempting to stop the virus in its tracks to learning to live with it.

But learning to live with Covid-19 should mean living with it strategically, by understanding as much as we can about our current state of risk and what we can do to minimize it. To keep Covid relatively at bay, really good data on spreading illness matters.

Health tools used in the home can tell us a lot about the dynamics of spreading illness that more common data sets like hospital admissions and lab test results cannot. For example, Kinsa anonymously tracks not only where and when illness is spreading, but also how it is spreading — that is, who spreads it to whom within a family, and how fast that transmission occurs. This is possible because Kinsa smart thermometers connect to an app that allows each family member to have their own profile, so the system can see which individual fell sick first and how quickly illness switched to another profile.

Looking at this aggregated and anonymized data at scale can provide critical insight into what precautions make the most sense to combat the viral foe we are facing. Kinsa data shows, for example, that Covid upended typical respiratory illness transmission patterns. From 2017 to early 2020 (before the rise of Covid), more than 75% of all cold and flu-like illness was brought into the home by children, who then gave it to others in the family. But when Covid arrived in early 2020, that pattern reversed. Adults became the index cases — they brought the virus into the home and spread it to their children.

This unique pattern has held true for each surge. With Omicron’s decline, we again see that transmission patterns are reverting back to normal, with children accounting for a greater proportion of household transmission. This is insight that no lab test will show.

So what does this mean for our return to normal? For removing masks indoors and in schools? If we know that adults are the primary source for household Covid-19 infections, it follows that the most impactful thing adults can do is to protect themselves to protect others. Getting vaccinated (and getting boosted) still remains one of the most powerful forms of protection, now and against future variants.

Kinsa’s mission is to stop the spread of infectious illness through earlier detection and earlier response. By arming ourselves with better information about where, when and how illness spreads, we give ourselves the best chance.

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Inder Singh

Inder Singh is the founder & CEO of Kinsa. Kinsa’s mission is to stop the spread of contagious illness through early detection & early response. kinsahealth.com