A: Good scientific metrics require accurate measurement and must be reflective of the situation in real life.
Unfortunately, Covid-19 creates opportunities for metrics upon metrics, some of which are not incredibly useful in guiding actions to stop the spread of the disease. With the help of a recent piece in the Washington Post, we will outline metrics that could better inform our responses to Covid-19.
POSITIVITY RATES over time are more useful than daily case and testing counts. The positivity rate is the number of positive tests divided by the total number of tests. If this ratio is high, it may mean only people with symptoms are being tested and we could be missing large numbers of pre-symptomatic individuals, allowing further spread. It is also important to note who is being tested. Broad testing coupled with low positivity rates are reassuring signals. See our previous DP post on positivity rates.
UNLINKED INFECTIONS identify new pathways for spread versus average spread in a population, the reproduction number or R. R is the average number of people a person with the disease infects. The goal is to decrease this number under 1. Unfortunately, R varies greatly across environments and is historical information by the time it is calculated and reported. Tracking the number of unlinked infections, infections with no known connection to an infected person or event, would signal areas in need of stronger contact tracing and attention. Contact tracing infrastructure is required and essential in tracking unlinked infections and is very limited in the US to date.
TIME TO ISOLATION and CASES AMONG THOSE QUARANTINED are essential metrics of contact tracing programs. Successful contact tracing programs require coordinated efforts and systems to briskly identify and isolate individuals with infection and quarantine exposed contacts. Isolation is for people with symptomatic or confirmed infection. Quarantine is for people who have not tested positive or shown symptoms, but are likely to have been exposed. If most new cases are identified among those already quarantined, transmission of the virus is squashed.
WORKFORCE INFECTION AND DEATHS inhibit our healthcare infrastructure. With many professionals deployed from various specialties to treat Covid-19, workforce infection limits the management of Covid and all other conditions. Workforce infection is modifiable with adequate personal protective equipment and effective systems of care.
TRENDS IN EXCESS MORTALITY track overall deaths and not just those directly attributable to Covid-19 infection. Excess mortality is calculated by comparing current mortality in a given population with historical information. The effects of Covid-19 are far worse if access to existing therapies for other conditions become compromised.
SHIFTING RECOMMENDATIONS, while frustrating, offer up to date information for use in real time. We are learning about this new virus every day! New information should shift our approach to contain this virus as quickly as possible so that we can move forward without Covid-19.
https://www.washingtonpost.com/…/how-amateur…/
