Happy hours seem like a distant memory these days. And they might stay that way…
Here in Baltimore at 5 p.m., you’d find restaurants and bars packed wall-to-wall with folks. But for months, these once busy places sat empty. It was only yesterday that the stay-at-home order lifted in the city. And even now, bars are only allowed outdoor seating.
As states around the country reopen, people are excited to get back to business as usual. But that won’t be the normal we’re used to…
That’s because we’ve learned that nearly all COVID-19 infections happen in crowded, close-contact, indoor settings just like happy hour spots.
In fact, scientists have traced outbreaks to events including:
- Choir practice
- Zumba class
- Dinner at a crowded restaurant
- A cruise
- A wedding
Activities like these where one person infects many in attendance are called “superspreader events.”
According to a study out of The University of Hong Kong late last month, these events account for a vast majority of infections. In fact, just 20% of people with COVID-19 accounted for 80% of total transmissions. Another 10% of those infected spread it to just a few people, like family members.
This 80-20 rule applies to other diseases too. It even has a name – the Pareto principle. To make it simpler, it states “80% of the effects come from 20% of the causes.”
Here’s what that looks like in a sample group of 100 people:
Number Who Spread COVID-19
Number Who Contract COVID-19
80 (superspreader events)
So 30 people infected all 100 people in this example group. That leaves 70% of folks who didn’t infect anyone else.
Read that again: 70% of people infected with the virus didn’t pass it on to anyone else.
Does this mean we can jump back into business as usual and head back to that cramped, stuffy bar? Of course not. We still need to exercise common sense. Handwashing and avoiding crowded places are still good practices.
We also know from the Hong Kong study that all of the superspreading events happened indoors.
Japan has seen a relatively low number of transmissions. Many folks credit that to a “3Cs” rule the government implemented. It told citizens to avoid:
- Closed spaces
- Crowded places
- Close-contact settings
In my weekly COVID-19 briefings with my senior analyst Matt Weinschenk, I covered some of these events already. The choir practice in Washington is a good example – 61 people went into a closed space to practice. Even though they followed the guidance at the time, one person was sick and not showing symptoms yet.
From those 61 folks, there were 32 confirmed cases and 20 suspected. So it almost got everybody… 88% if you count the probable ones.
Matt also covered the case of the restaurant in China where one infected person spread the virus to many other diners. It was likely the result of an air conditioning unit that spread the particles around.
So I’d add another C to this list: Constricted air flow. If you’re indoors for anything, you want to make sure the air flow is good and that there are high-grade air filters in place. That’s why I’m not as worried about airplanes, since they have medical-grade HEPA air filters in most planes now.
We still don’t know if those 20% of folks doing the most spreading are superspreaders themselves or if they’re just in environmental situations where they can infect a lot more folks. So, there might not be anything different about the strain of the virus or a person’s immune system that makes them more likely to infect a bunch of people. It could just be bad luck that they, say, attended a wedding the day before they showed symptoms and infected a ton of the attendees.
That’s why I think it’s absurd that folks have stayed inside for so long. Fresh air and sunshine are necessary for our physical health. And now we know that you’re much less likely to get sick if you’re outdoors.
So don’t let the overwhelming fear of COVID-19 consume your whole life. Given this information from Hong Kong and similar studies from modelers in the U.K., we know that we’re not nearly in as much danger if we’re outdoors. That’s good timing for the summer.
Do what I do and get outside as much as possible. Go for walks. Work in your garden. Meet up with a friend and visit on each other’s porches. Practice some yoga in the sunshine. And most of all, stay educated and take control of your own health.
What We’re Reading…
- Matt’s explanation of the restaurant study.
- Something different: Plants choosing to move on their own?
Here’s to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
June 9, 2020