R, the reproduction number, in COVID-19 epidemic decision-making

Abstract Background The COVID-19 pandemic flooded the public discourse and media with a multitude of epidemiological terms. Among them, the Reproduction number (R) was in overabundance. Our aim was to assess the impact of daily R data on the epidemiological analysis of the outbreak in Israel and subsequent decisions. Methods The period between September 2020 and January 2022 was included in the study. That corresponded with mass usage of PCR tests, prior to Omicron upsurge and the increasing introduction of antigen tests, with lower sensitivity and specificity. The analysis of COVID-19 incidence involved employing graphical representations of daily R values. These computations, derived from the data encompassing the summation of the preceding 10 days, were compared with the daily case number curve during the study period. Results Between September 2020 and January 2022 there were three major waves of COVID-19 morbidity. Study of the incidence and R values presents discrepancies, that are inherent in the process of data collection on the one hand and the computation of R on the other. Conclusions Applying R in policymaking is challenging, due to gaps regarding timeliness and actual incident case numbers. Albeit an important biological and epidemiological parameter, R is less suited to support on-going decision-making process, and may have been over-used throughout the COVID-19 pandemic. Alternatively, an in-depth analysis of incidence and trends may provide better approach to public health decision-making.