COVID curve considered

I was impressed by the insightful and timely article, in the April 15 edition of the La Conner Weekly News, reporting on the rate of Covid-19 virus infection in Skagit County.

We are all learning, or should be learning, more every day about the spread of the disease, and the correlation with good health and sanitation practices, and the ever present health risk from human interaction.

I was never sure of what exponential growth meant.

This, too, we have learned: The epidemic “doubling time” is the rate or time it takes for a disease to infect twice the number of people.

It is a measure of exponential growth.

In explaining and exploring this concept, you did a nice job of illustrating the “doubling time” for the number of new infections to double.

As you reported, from February 21-March 18 it took only about four days for the number of new cases to double.

The Skagit County Chorale practice, on March 10, (before any Stay Home order) was followed shortly thereafter by confirmed infections among most of the participating members. This unfortunate event, early in our learning curve, taught the medical community, and all of us, that the virus can also be transmitted, not just by larger sneeze or cough viral droplets, but by smaller viral aerosols, or microscopic particles.

On March 23, Governor Inslee issued a Stay Home Stay Healthy order. As you reported, since the Governor’s mandated that all of us participate in the taming of this epidemic, the doubling time or rate of spread of the infection in Skagit County has lengthened. From the very rapid spread every four days a month ago, the doubling time from March 31 to April 17 is now 17 days. The rate or speed of infection is slowing or “flattening” as shown on the epidemiologic/epidemic curve. The State Department of Health website is a good source for keeping track of all of this: http://www.doh.wa.gov.

There can be no question but that public education and awareness, and the general acceptance of a “new normal” in hygiene and social interaction has made a huge difference. An additional, contributing factor in Skagit County is the urban-rural composition. With a population of about 128,000, the urban segment comprises maybe 60% of that number. The four biggest towns range from only about 33,000 residents to about 11,000. Social distancing is, significantly, a matter of geography.

Buz Humphrey