The Key to the Pandemic
An article in The Atlantic called “This Overlooked Variable Is the Key to the Pandemic” talks about how COVID 19 spreads and how we should be responding based on that. The overlooked variable they are discussing is k: the measure of dispersion. Covid is a very over disperse pathogen which means there are a few people who infect many people, however most people infect 0 or 1 people. In other words, COVID spreads through clusters. The article talked about a couple things we could be doing better based on this information. First, we should be doing backwards contact tracing as opposed to forward contact tracing. In other words we should be finding the people who affected the patient rather than the people the patient could have affected. Since the majority of people don’t actually spread the virus to anyone, it is unlikely that the patient actually spread the virus. And because the majority of people who get the virus get it from a super spreader, it is likely the person who infected the patient also infected many others. So if you find the person who gave it to the patient, then you can find all the people who came in contact with that person and you will be more likely to find more infected people. The article isn’t saying that you shouldn’t do both types of contact tracing, but if you can only do one then backward tracing should be prioritized.
The other thing this article recommends is to use fast tests even if the false negative rate is high. Many regulatory agencies in the U.S. have not approved these tests however because the false negative rate is so high. But if you are testing people in clusters, and the test identifies some people in the cluster as positive, then you can assume the whole cluster got infected and have everyone quarantine, or you can have everyone get PCR testing done.
The article called out a few countries that have been taking precautions aimed specifically at cluster busting. One country they mentioned was Japan. Japan noticed how COVID spread very early on and therefore put most of their focus towards avoiding the three C’s: crowds in closed spaces in close contact. Hitoshi Oshitani, a member of the National COVID 19 Cluster Taskforce at Japan’s Ministry of Health made the analogy that when we are looking at a forest, we should not be looking for trees, we should be looking for clusters.
With this information about how COVID spreads you can really see how universities such as Cornell have been so successful. Even though Cornell does not use the rapid testing techniques as discussed in the article, they have access to their own facilities which can get PCR testing results back in around 24 hours. Also, the idea of backward contact tracing happens automatically since everyone is required to get tested frequently. So a whole cluster will be tested no matter what. This allows Cornell to isolate the cluster and have everyone quarantine until they are no longer contagious. Cornell also regulates large gatherings on campus, as well as enforcing strong consequences for large gatherings off campus.
https://www.theatlantic.com/health/archive/2020/09/k-overlooked-variable-driving-pandemic/616548/