Did Covid-19 spread mostly via homes and close contacts?

In the spring of 2020, I was looking at contact tracing data for Utah and they had found that about 2 out of 3 cases traced back to a home or close social contact (usually in the home).

But – there might be a problem with drawing that conclusion, that I will get to in a moment.

This study makes a similar conclusion:

“Micro evidence contradicts the public-health ideal in which households would be places of solitary confinement and zero transmission,” writes University of Chicago economist Casey B. Mulligan. “Instead, the evidence suggests that ‘households show the highest transmission rates’ and that ‘households are high-risk settings for the transmission of [COVID-19].’”

At first glance, the findings are a bit surprising. Models early in the pandemic assumed less transmission would occur in households. This explains why Cuomo was surprised when he learned 66 percent of those hospitalized with COVID had been staying at home—it ran counter to the pre-pandemic science, which showed viruses are more commonly spread in work environments and schools.

Source: New Study Reveals That Stay-at-Home Orders Backfired. Here’s Why – Foundation for Economic Education


It may be that it was much easier to do contact tracing for those who contracted the disease at home. For example, in my state, if someone had contacted the disease at a large outdoor event (the only ones allowed at the time were BLM-affiliated, and later, right-wing protests in Portland, Eugene, for example), they cut off the trace, saying it was not possible to figure out who was the source.

It is easiest to contact trace home-based contacts, direct social contacts and work place group contacts so you get sample bias.

If we assume most cases were contracted in the home, perhaps this is because mitigation measures taken outside the home – e.g. at work – worked. So there is that possibility.

Another possibility is most cases really do transfer via homes. Which is not far fetched either. Even if most stayed at home, it is likely that some had to go out for food, work, health care, etc. Then brought the disease back into the home. And No one wears an N95 mask 24×7 in their home (assuming masks work).

Plus, there are many and especially low paid workers delivering items to our cars and homes – who at the end of the day return to live in dense congregate living situations – e.g. apartments, even shared houses.

Our pandemic response was to transfer risk from the well off to the less well off, living in denser housing. Hence, more transmission occurred in homes.

Telling everyone to stay at home and indoors may end up having been a very bad recommendation. At no previous time previously had  lockdowns ever been done on such a scale. We were conducting a national medical experiment without consent of those being studied (which is against the law).