Tuesday, March 17, 2020

The R⌀ and Why it Matters

What is the coronavirus R0? And how does it help guide as as to what happens next, and where the pandemic is going? On your block, neighborhood, city--and world?

Simply put, R0 is how many people one infected person can infect on average.

But it is a changing and context-dependent number, not a constant.

It's important to understand what it is, and what it is not.

The following is from emcrit.org, bringing "the best evidence-based information from the fields of critical care, resuscitation, and trauma and translate it for bedside use in the Emergency Department (ED) and the Intensive Care Unit (ICU)", dated 3/2/20:

"R⌀ is the average number of people that an infected person transmits the virus to.

"If R⌀ is <1, the epidemic will burn out.

"If R⌀ = 1, then epidemic will continue at a steady pace.

"If R⌀ >1, the epidemic will increase exponentially."

It took me a while to really get it, so give yourself another read to digest this.

And what's the number? As of this month, "current estimates put R⌀ at ~2.5-2.9 (Peng PWH et al, 2/28)."

That means that every person who is infected will infect, on average, 2.5 to 3 more people. That means that the epidemic will increase exponentially.

Remember, it's not a constant. "R⌀ is a reflection of both the virus and also human behavior. Interventions such as social distancing and improved hygiene will decrease R⌀."

Here's what we know: "Control of spread of COVID-19 in China proves that R⌀ is a modifiable number that can be reduced by effective public health interventions."

So R0 changes over time. R0 changes with circumstances. R0 changes with human behavior.

You can influence it. Each and every one of us can.

Here's an example of influence:

"The R⌀ on board the Diamond Princess cruise ship was 15 – illustrating that cramped quarters with inadequate hygiene will increase R⌀ (Rocklov 2/28)."


This means that for each person who was infected in that closed environment, fifteen other people got sick. Makes sense, though: cramped quarters, inadequate hygiene, and people who are already infected. High transmission context.

So the goal is to do the opposite, and that's what all the advice is about, how to lower R0. How?

Social distancing, good hand-washing, disinfectants for inanimate objects like plastic, steel and glass. Staying home when you're sick.

That's how.

Waiting's a poor plan. That just means more cases. Even R0=1 means new people get infected. Maybe you, or someone you care about.

We have to get R0 below 1 to turn the tide, or it's going to be a long, unpleasant trip. You, me, and even them.

Everyone matters.

Sunday, March 15, 2020

Truth and Lies in the Time of the Pandemic

There is a lot of misinformation floating around about #coronavirus. While new information is coming every day, and there's plenty we don't know, we do know a lot.

The other day, a man told me that he was sure he'd heard on CNN that 80% of people already had the virus, so obviously it wasn't big a deal.

I told him he was wrong, politely, then again. Then I wished him a good day and left.

I bothered to talk with him because someone like this will make bad decisions--about his own hygiene, about social distancing, about his own illness should he get sick--and those decisions put himself and others at greater risk.

He will pass on incorrect information, and--like the virus itself--that information spreads, creating patterns of action or inaction that affect us all.

I am learning to tell people that they are wrong gently. Because either they're tending toward being open to what I say, or they're tending away from it.

If the former, my being emotionally loud creates more emotional turmoil in the interaction, which is likely to get them defensive and less able to hear me.

Sure, it might make me feel better for a moment and help me let off steam from my own stress around all this, but does it accomplish any goal of communicating new ideas?

Not so much.

Or, in other words, if someone is hard of listening, speaking louder doesn't work better.

So, how to asses the veracity of information? Ask yourself some questions.

Who is telling you this? Can you find another, corroborating source? Who else is saying something similar? Are any of the sources reputable?

Think critically before you post, or email out to a list. When you have a readership, you have a greater responsibility to spread good information. Don't trust something just because someone says they're an expert, a doctor, a researcher.

Every person is part of this disease transmission. We are all truly connected, and this pandemic is showing us this, up-close and personal. What we believe affects how we act, and that has everything to do with infection vectors.

Here are some lies, or myths, making the rounds. Give them a quick look.

And if you have more such lists, let me know.