Air Purifiers, Air Filters, and the Best DIY Hacks to Reduce the Coronavirus Risk

How to clear the air in your home to protect against airborne Covid-19 transmission

Illustration: Matija Medved

Efforts to prevent Covid-19 infections have focused largely beyond the home, emphasizing crowded indoor public spaces. But after our son attended an event where he could have been exposed to the coronavirus, and we were told it could take a week to get test results, I began a quest to understand what to do if someone brings the virus home without knowing they are infectious, and how to create a sustainable defense for the “just in case” scenario, amid so many uncertainties.

First question: What are the odds family members will get infected?

“It clearly happens,” says Ashish Jha, MD, a practicing internist and professor of medicine at Harvard Medical School. “The attack rates are nowhere near 100%, they’re maybe 15 to 20%.” In other words, on average across all households with an infected person, 15% to 20% of family members would get the disease. A review of 40 studies on the topic, published August 1 but not yet peer-reviewed by other scientists, put the figure at 18.8%. Of course, many factors can affect these odds, including how many people are living in a given home and how crowded it is.