  In a recent work we introduced a novel method to compute the effective
reproduction number $R_t$ and we applied it to describe the development of the
COVID-19 outbreak in Italy. The study is based on the number of daily positive
swabs as reported by the Italian Dipartimento di Protezione Civile. Recently,
the Italian Istituto Superiore di Sanit\`a made available the data relative of
the symptomatic cases, where the reporting date is the date of beginning of
symptoms instead of the date of the reporting of the positive swab. In this
paper we will discuss merits and drawbacks of this data, quantitatively
comparing the quality of the pandemic indicators computed with the two samples.
