Even before public announcements of the first cases of COVID-19 in Europe were made, in late January 2020, signs were circulating on social media that something strange was happening. A new study by researchers in IMT School of Advanced Studies Lucca, published on Scientific Reports, identified tracks of increasing concern about pneumonia cases in posts published on Twitter in seven countries, between the end of 2019 and the beginning of 2020. Analysis of the posts shows that the “complaints” came precisely from the geographic regions where the main outbreaks developed posteriorly.
To conduct the research, the authors first created an exclusive database of all messages posted on Twitter containing the keyword “pneumonia” in the seven most spoken languages of the European Union – English, German, French, Italian, Spanish, Polish and Dutch – December 2014 to March 1, 2020. The word “pneumonia” was chosen because the disease is the most serious condition induced by SARS-CoV-2, and also because the 2020 flu season was milder than the so there was no reason to think that you are responsible for all the mentions and concerns. The researchers then made a series of adjustments and corrections to the database posts in order not to overestimate the number of tweets mentioning pneumonia between December 2019 and January 2020, that is, in the weeks between the announcement by the World Health Organization (WHO) that the first “pneumonia cases of unknown etiology” were identified – on December 31, 2019 – and the official recognition of COVID19 as a serious communicable disease on January 21, 2020. In particular, all tweets and retweets containing links to news about the emerging virus have been removed from the database to exclude mass media coverage of the emerging pandemic from counting.
The authors’ analysis shows an increase in tweets mentioning the keyword “pneumonia” in most European countries included in the study as early as January 2020, in order to indicate continued concern and public interest in cases of pneumonia. In Italy, for example, where the first blocking measures to contain COVID-19 infections were introduced on February 22, 2020, the rate of increase in mentions of pneumonia during the first weeks of 2020 differs substantially from the rate observed in the same weeks in 2019. This means that potentially hidden points of infection were identified several weeks before the announcement of the first local source of COVID-19 infection (February 20, Codogno, Italy). France exhibited a similar pattern, while Spain, Poland and the United Kingdom were delayed by 2 weeks.
The authors also geographically located more than 13,000 pneumonia-related tweets in the same period and found that they came from exactly the regions where the first cases of infections were reported later, such as the Lombardy region in Italy, Madrid, Spain and Île de France.
Following the same procedure used for the keyword “pneumonia”, the researchers also produced a new set of data containing the keyword “dry cough”, one of the other symptoms later associated with the COVID-19 syndrome. Even so, they observed the same pattern, that is, an abnormal and statistically significant increase in the number of mentions of the word during the weeks leading up to the outbreak of infections in February 2020.
“Our study adds to the existing evidence that social media can be a useful tool for epidemiological surveillance. They can help intercept the first signs of a new disease, before it proliferates undetected, and also track its spread,” says Massimo Riccaboni, full professor PhD student in Economics at Escola IMT, who coordinated the research.
This is especially true in a situation like the current pandemic, when failures to identify early warning signs have left many national governments blind to the unprecedented scale of the impending public health emergency. In a successive phase of the pandemic, monitoring social networks could help public health authorities to mitigate the risks of resurgence of contagion, for example, by adopting stricter measures of social distance where infections appear to be increasing, or vice versa, relaxing them in other regions. These tools can also pave the way for an integrated system of epidemiological surveillance managed globally by international health organizations.
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