Letter: Scary numbers: How exponential viral growth works

Posted 3/30/20

To the editor:

Exponential spread gets discussed a lot but people don't seem to get it or its importance. Here is an illustration of a how a virus spreads exponentially. The numbers, with the …

This item is available in full to subscribers.

Please log in to continue

Log in

Not a subscriber?


Start a Subscription

Sign up to start a subscription today! Click here to see your options.

Purchase a day pass

Purchase 24 hours of website access for $2. Click here to continue

Day pass subscribers

Are you a day pass subscriber who needs to log in? Click here to continue.


Letter: Scary numbers: How exponential viral growth works

Posted

To the editor:

Exponential spread gets discussed a lot but people don't seem to get it or its importance. Here is an illustration of a how a virus spreads exponentially. The numbers, with the exception of the incubation time, are hypothetical.

One asymptomatic infected person comes in contact with 10 people in a day and infects two. Those two people contact 10 people the next day and each infects two. Each day this occurs so two becomes four, four becomes eight, eight becomes 16. The mean incubation time is seven days so no one becomes sick until 256 people have become infected. If 20 percent of the infected people become ill then at the end of a week 50-plus people have symptoms. That first person might not have symptoms so you might go another week and have more than 16,000 infected before it really feels like a problem.

The sooner you can catch that one or two or eight and contact their contacts the better off you are at heading off a disaster. Given this logic, places with low disease events should be just a vigilant as hot spots. In the absence of testing our only other strategy is to limit contact so instead of 10 contacts we have zero. (Keep in mind “contacts” can include the pump at the gas station or the bag at the grocery store).

With regard to testing there is another way to test other than finding the virus and that is looking for our response to the virus by testing for antibodies. This can tell us, even or especially, the asymptomatic or minimally symptomatic who have or have had the disease. Proponents say it can become positive in as little as three days, although seven may be more realistic. The United Kingdom has purchased 50,000 home antibody testing kits that give a result in 15 minutes. They plan to test their reliability this week and if they do prove reliable will dispense another 2.5 million to get a handle on who has the disease, track contacts, and get those who are immune back into the work force. Getting this up and running in Rhode Island would give a huge boost to both getting a handle on the extent of disease and getting at least some of the economy up and running.

Finally on a hopeful note, we are so lucky to have Dr. Anthony Fauci running this show. There is no human being on the face of the earth who is better qualified to deal with this crisis.


Geoff Berg MD
26 Brownell St.
Warren

2020 by East Bay Newspapers

Barrington · Bristol · East Providence · Little Compton · Portsmouth · Tiverton · Warren · Westport
Meet our staff
Scott Pickering

Scott Pickering has been on the East Bay Newspapers team for more than two decades, since starting as a reporter for the Sakonnet Times. He's been editor of most of the papers, was Managing Editor of all the papers for many years, and became General Manager in 2012. Today he can be found posting to EastBayRI.com, steering news coverage, writing editorials, talking to readers, working with the sales team, collaborating on design, or helping do whatever it takes to get the papers out the door. Reach him at spickering@eastbaynewspapers.com.