During the pandemic we have all become familiar with a lot of epidemiological concepts.
One that was introduced to us early in 2020 is the “basic reproductive number”, or R0. This tells us about the intrinsic contagiousness of a virus, or its inherent capacity to be spread from one person to another in a particular population.
We also learned about the “effective reproductive number”, or Reff. This tells us about the rate at which a virus is actually spreading through that population.
With the emergence of BA.4/5, there has been some confusion around how these concepts help us to understand why one variant spreads faster than another.