LAUSR

International antibiotic awareness and stewardship campaigns use social media to disseminate campaign materials. Analysis of campaigns during 2016 and 2017 identified a wide range of hashtags in use, potentially leading to confusion and dilution of campaign message. The aim was to study the impact of different hashtags on the dissemination of information during European Antibiotic Awareness Day and World Antibiotic Awareness Week, November 2018. Tweets were extracted prospectively using Followthehashtag and analysed in Excel and R (14,400 tweets by 5,899 tweeters, with 60,222 retweets). Descriptive analysis and multivariable logistic regression analyses adjusted for potential confounders. There was a positive association between retweets received and inclusion of media, hashtag(s), mention of other tweeter(s), and number of followers. There was hashtag drift - e.g. unofficial #WAAW2018 hashtag was used more frequently than the official campaign #WAAW18 hashtag. Analysis of five popular hashtags from the European and worldwide campaigns found a positive association between retweets and the unofficial hashtag #WAAW2018 and the long-established #AntibioticGuardian hashtag. #AntibioticResistance (another official hashtag) was the most frequently used hashtag but did not have a consistent positive association with retweets. Analysis of the contribution of tweeters - tweeters, retweeters, and mentions of tweeters - demonstrated 32,534 accounts in total, 95% of which tweeted and/or retweeted, the great majority being retweeters. This study demonstrates the breadth of participation in international antibiotic awareness campaigns, but also the need for clarity about campaign hashtags, and the need to search beyond official hashtags when evaluating the impact of a campaign.