## A. What is Ro?

R_{o} (pronounced R sub naught) is a basic reproduction ratio, i.e. reproduction rate. In a report, the CDC states that R_{o }is a modeling term:

*“R*_{0}* is not a biological constant for a pathogen, a rate over time, or a measure of disease severity, and R*_{0}* cannot be modified through vaccination campaigns. R*_{0}* is rarely measured directly, and modeled R*_{0}* values are dependent on model structures and assumptions.” *[Delamater PL, Street EJ, Leslie TF, Yang Y, Jacobsen KH. *Complexity of the Basic Reproduction Number* (R0). Emerg Infect Dis. 2019;**25**(1):1-4. https://dx.doi.org/10.3201/

There are various methods for calculating R_{o}. The SEIR model for the equation is:

R_{o } = 1+ K (τ_{E + } τ_{I}) + K^{2} (τ_{E}τ_{I})

All of the terms in this equation are dependent upon the actual number of infected individuals. If the number of infected individuals is unknown, then the equation stands without an answer.

Small scale antibody studies show that the number of people infected may be from 7 to 85 times more than the number of people tested. Hence, no one really knows what the true R_{o} number is.

Wikipedia states:

*“Since R*_{0}* is rarely observed in the field and is usually calculated via a mathematical model, this severely limits its usefulness.” https://en.wikipedia.org/wiki/ Basic_reproduction_number#Estimation_methods*

In a recent publication, the CDC stated that the R_{o} for the COVID-19 virus is 5.7. This is based on the doubling time for the tested COVID cases. [https://wwwnc.cdc.gov/eid/_{o} to be 3.4.

The current method of determining R_{o} is flawed in that it requires data that does not exist and may never exist.

*“Since R*_{0}*is rarely observed in the field and is usually calculated via a mathematical model, this severely limits its usefulness.” https://en.wikipedia.org/wiki/*Basic_reproduction_number# Estimation_methods