I mentioned a while ago that San Miguel County, Colorado (home to the ski town of Telluride, where movie stars congregate each January for Robert Redford’s film festival) is starting an antibody test that hopes to test the majority of the county’s 8,000 residents. One optimistic theory is that millions of Americans have already had coronavirus so lots of people are (hopefully) immune and we’re that much closer to herd immunity. Because of the testing shortage, there hasn’t been much in the way of random sampling yet.
Here are the results of the initial wave:
Posted on: March 24, 2020
First Set of Results for COVID-19 Blood Test
(March 24, 2020) — San Miguel County, CO — San Miguel County Department of Public Health and Environment today received the results for the first group of those who had the COVID-19 ELISA blood test.
The group of 645, first responders and their families, all tested negative. Two parties had a mild signal change, although not enough to change the negative test results. In some cases, this can indicate early seroconversion. Public Health has spoken directly to these two individuals.
“Although the results did not come back as positive, we have asked them to self-quarantine for 14 days. Additionally, we have requested them to take the PCR nasal swab to compare the two tests,” Grace Franklin, Director of Public Health said.
It sounds like they should have done the PCR test along with the antibody test to compare how they work.
Negative blood test results indicate that a person has not had exposure to the virus and therefore remains susceptible to becoming infected. This test should be repeated after 14 days to detect any changes in immune status.
Okay, so none of the 645 tested positive, two were in a gray area and 643 negative.
These first responders are townies rather than international jet setters.
Some other ski towns have had bad outbreaks, but there could be a fair amount of randomness in the results due to the small sample size of visitors. Telluride is extremely remote at 9,000 feet at the end of a single road in the huge San Juan Mountains of southwest Colorado. One airline, Boutique Air, serves it, but lots of its regulars arrive on private planes. It could be that it just happened that virtually nobody with virus showed up this year. Or … what?
Pattern recognition has proven difficult in this epidemic. For example, I’ve been pointing out the role of skiing in the spread. But here’s a famous ski town with, apparently, very little.
Tyler Cowen asks, “Where does all the heterogeneity come from?” and cites numerous seemingly contradictory numbers from around the world.