Before revision:  Results. The population appeared to be mostly composed by serial tweeters tweeting about everything including vaccines. Tweets favourable to vaccination accounted for 75\% of retained tweets, undecided for 14\% and unfavourablefor 11\% . Twitter activity of the Italian public health institutions was negligible.
After revision:  Results. Vaccine-relevant tweeters interactions peaked in response to main political events. Out of retained tweets, undecided for 14\% and unfavourablefor 11\% . Twitter activity of the Italian public health institutions was negligible.