**1. Introduction**

Electronic cigarettes or e-cigarettes are handheld battery operated devices that heat liquid and deliver an aerosol that simulates smoking. They may also be referred to as electronic nicotine delivery systems (ENDS) in certain literature. In conjunction with the increased use of these devices [1], a health concern has emerged linking the use of e-cigarettes with pulmonary illness [2–4]. The Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) are investigating a multistate outbreak of lung injury associated with the use of e-cigarette or vaping products [5,6]. All of this information is generating widespread debate, which we can be framed as a health scare [7,8] similar to other scares such as the current COVID-19 scare, as well as the H1N1 virus (swine flu), trans fats, Ebola, and the mobile phone usage health scare [9,10]. Health scares can be described as campaigns that attempt to alert the public of a particular substance or activity that can lead to a negative effect on health [11].

Tobacco can be traced back thousands of years and was grown as a crop from around 5000–3000 BC, led by the communities in the Andes, South America (Ram, Nathan, Balraj, 2017). Native Americans would cultivate and smoke tobacco for medicinal and ceremonial purposes. Tobacco eventually spread around other continents and eventually all around the world [12]. Henceforth, it had many thousands of years to become ingrained within human culture and society. In the early years of the

20th Century, cigarette and nicotine marketing through print, television, and radio only helped to boost sales. In recent years, and after the dangers of traditional forms of smoking, e-cigarettes have risen in popularity.

The tobacco industry is argued to be one of the most profitable and deadly industries that exists with cigarette retail values in 2013 hitting \$ 722 billion and there being 5.7 trillion cigarettes in circulation [12]. In today's digital world, it is possible for consumers and the general public to offer their views and opinions across social media platforms. One of the most open platforms to converse about public health is Twitter, where it is also possible to extract tweets for academic research purposes. Previous research has utilised Twitter to identify public views, key discussions, content, and stakeholders related to health scares [13–15]. Twitter can be used to study and understand the context of the current e-cigarette health scare. Twitter is an important platform to study because it has the potential to shape mainstream news because tweets can be embedded in online news stories, as well as highlighted in traditional media (such as TV or radio), amplifying their reach. Health scares need to be studied in the context in which they occur, and one method of studying them is through the use of Twitter [10,16]. This is because Twitter provides citizens with a platform that permits the rapid sharing of public views and opinions and allows these views to become viral and highly shared, regardless of their factual truth; henceforth, this is an important and significant area to study. Moreover, the debate around the safety of e-cigarettes is likely to be of interest to a wide variety of stakeholders.

Our study sought to examine an influential time-point related to e-cigarettes from 2019 when there was a heightened interest in e-cigarette safety. We identified a gap in knowledge as no previous empirical work has conducted an analysis of Twitter data related to this time point. Moreover, this is an important topic to study because it aims to build an understanding of how social media may play a role in the global dissemination of amateur and unfounded speculation against accepted medical research. This type of research is increasingly important, as we find medical studies being socially challenged by various social media networks at an increasing rate. We utilised a mix of social network, automated text, and link analysis in order to identify network structures, influential users, the most utilised words, and hashtags.

We sought to address the following research questions:


A further objective of the study was to review existing literature in order to develop a flowchart for consumers to assess the safety of e-cigarettes by analysing public views from Twitter and by drawing up current advice from health authorities and domain experts. This flowchart is likely to be of interest to consumers and public health agencies across the world.
