Using Text Mining and Sentiment Analysis to Analyse YouTube Italian Videos Concerning Vaccination

"[M]onitoring social networks could be a good proxy to evaluate vaccine hesitancy..."

In Italy, YouTube dominates the video-based social media platforms. It was on YouTube that the North American anti-vaccine movement was able to upload and share conference recordings free of charge to reach a wider audience. Perhaps due in part to the influence of (mis)information shared online, from 2013 onwards, vaccination coverage in Italy has seen a decreasing trend, and, in 2017, a measles epidemic caused 5,000 cases and 4 deaths. For this reason, on June 7 2017, a decree-law was passed that increased the number of vaccinations compulsory for school attendance from 4 to 10 and proposed a vaccination campaign. This study aims to understand what the sentiment towards vaccines on YouTube is and to detect if and how Italians' opinions changed from the period before the introduction of the decree-law to the following period, i.e., after the vaccination campaign.

Using co-occurrence network (CON) and sentiment analysis, the researchers analysed the topics of YouTube Italian videos on vaccines in 2017 and 2018. Figure 1 in the paper shows that, in 2017, the terms "compulsory" and "choice" have high degrees of centrality within the network. The researchers observed many connected cliques and small clusters stressing strong concern and perplexities. In 2018, the most central words in the network in order of importance are: "medical doctor", "child", "deadline", "vaccination", "ministry", "health", and "parent". There was a change in the importance of terms such as "freedom", "choice", "risk", and "compulsory", suggesting that the previous negative discussions about vaccinations are weakened, bringing the speech back to less polemical tones. That is, in 2018, users discussed this topic less critically, no longer emphasising the risk and danger of vaccines but instead trying to understand and address the consequences of the law-decree regarding the documentation required for access to school.

The CON confirms that in 2017, the prevailing sentiment was negative (52%), whereas in 2018, the positive sentiment was 54%.

This study highlights that vaccination campaigns on social networks could be an effective instrument of health policies and a weapon to fight ignorance and misrepresentations of non-qualified people influencing individuals' decision-making. The researchers hope to stimulate public authorities to invest in digital communication for spreading health information, raising awareness among increasingly younger users, and using a type of communication that is increasingly popular. "The competent authorities should invest and apply policies for correct information on the web by financing projects and qualified operators capable of coping with the new digital age."