The COVID-19 pandemic has made it clear that effective public health messaging is an indispensable component of a robust pandemic response system. In this article, we review decades of research from the interdisciplinary field of communication science and provide evidence-based recommendations for COVID-19 public health messaging. We take a principled approach by systematically examining the communication process, focusing on decisions about what to say in a message (i.e., message content) and how to say it (i.e., message executions), and how these decisions impact message persuasiveness. Following a synthesis of each major line of literature, we discuss how science-based principles of message design can be used in COVID-19 public health messaging. Additionally, we identify emerging challenges for public health messaging during the COVID-19 pandemic and discuss possible remedies. We conclude that communication science offers promising public health messaging strategies for combatting COVID-19 and future pandemics.

Background: As user modification can alter the addictiveness and toxicity of electronic nicotine delivery systems (ENDS), more research is needed to understand the types, motivations, risks, and information sources that lead to these product alterations. YouTube has been identified as a major platform where ENDS users obtain and share information about ENDS products and modifications. However, a comprehensive study of ENDS modification videos on YouTube is lacking. Objective: This study aimed to analyze the content of YouTube videos depicting modifications of ENDS. Methods: YouTube was searched in March 2019 to identify videos depicting ENDS modifications. Search terms were derived from interviews with ENDS users and current literature. We used 28 search phrases that combined the words vape and vaping with modification-related key terms (eg, custom build, modification, and dripping). The final sample included 168 videos. Results: Videos were 1 to 108 min long (median 9.55). Presenters were largely male (117/168, 69.6%), white (94/168, 56.0%), and older than 25 years (94/168, 56.0%). Most videos gave how to instructions (148/168, 88.1%), but few offered warnings (30/168, 17.9%) or mentioned commercial alternatives to modifications they presented (16/168, 9.5%). The ENDS devices most often featured were drippers (63/168, 37.5%) and refillable tanks (37/168, 22.0%). The most often modified ENDS components were coils (82/168, 48.8%) and e-liquids (34/168, 20.2%), which included adding other substances, such as cannabis, to the e-liquids (6/168, 3.6%). Most videos portrayed ENDS modifications positively (106/168, 63.1% positive; 60/168, 35.7% neutral; and 2/168, 1.2% negative) and were either neutral or positive in their overall portrayal of ENDS devices (78/168, 46.4% positive; 89/168, 53.0% neutral; and 1/168, 0.6% negative). Conclusions: This study identified several concerning trends in popular YouTube videos on ENDS modifications, including lack of warnings, the addition of marijuana derivatives to e-liquids, and the positive portrayal of ENDS devices and modifications. By identifying the types of modifications (coil and e-liquid being the most prevalent), this study sets an agenda for research on the effects of modifications.

We examined how a nicotine fact sheet influenced smokers’ beliefs about nicotine and electronic cigarettes (e-cigarettes), a potentially less harmful alternative to conventional cigarettes. In an exploratory online experiment, 756 US adult current and recent former smokers (quit in the past 2 years) were randomized to view a nicotine fact sheet or control messages (bottled water ads). Effects of the nicotine fact sheet on perceived nicotine addictiveness, nicotine risk, comparative risk of e-cigarettes, and dual use intentions were analyzed using log-Poisson regression with robust error. Linear regression analyzed effects on perceived absolute risk and switching and information seeking intentions about e-cigarettes. Compared to control, the nicotine fact sheet doubled the probability of disagreeing that nicotine is the main cause of smoking-related disease (26.2% vs. 12.7%, RR = 2.06, 95% CI = 1.51, 2.82, p < 0.001). However, nearly three quarters of participants viewing the nicotine fact sheet still thought that nicotine is the main cause of smoking-related disease. The nicotine fact sheet increased smokers’ intentions to seek information about e-cigarettes (b = 0.45, 95% CI = 0.15, 0.74, p = 0.003). We did not find evidence suggesting unintended consequences of the nicotine fact sheet on smokers’ e-cigarettes risk perceptions or use intentions (e.g., increased dual use intentions or reduced absolute e-cigarette risk perception).

Background: Cigarette pictorial warning labels (PWLs) could produce stronger quit intentions than text-only warning labels (TWLs) due to greater emotional arousal. Yet, it remains unclear whether PWLs that elicit different levels of emotions produce different outcomes. To better understand the role of negative emotions in the effects of PWLs, this study developed two sets of PWLs arousing different emotional levels (high vs low) but equally high on informativeness and compared them to each other and to the current TWLs.Methods: Adult US smokers (n=1503) were randomised to view nine high-emotion-arousing or low-emotion-arousing PWLs or TWLs. After each label, participants reported the negative emotions they felt while looking at the label. After seeing all the labels, participants reported their intentions to quit smoking. Mediation analyses tested whether message condition influenced quit intentions indirectly through negative emotions.Results: Compared with TWLs, PWLs produced higher levels of negative emotions (b=0.27, SE=0.04, p<0.001). Compared with low-emotion arousing PWLs, high-emotion-arousing PWLs produced higher levels of negative emotions (b=0.24, SE=0.07, p<0.001). Higher negative emotions predicted stronger quit intentions (b=0.20, SE=0.03, p<0.001). Negative emotions mediated the effects of PWLs versus TWLs and high-emotion-arousing versus low- emotion-arousing PWLs on quit intentions.Conclusions: The results provide additional evidence for negative emotions as the mechanism through which PWLs motivate smokers to consider quitting. The findings call on the Food and Drug Administration to design and implement high-emotion-arousing cigarette warning labels.

Introduction Tobacco industry studies on consumers’ perceptions of modified risk claims (MRCs) often had important omissions (eg, no control group, not investigating whether consumers understand what ‘switching completely’ means). This study examined the effects of IQOS MRCs on risk perceptions and behavioural intentions. Method Based on tobacco companies’ MRCs, we manipulated three MRC language features: explanation about ‘switching completely’ (absent vs present), number of diseases (single vs multiple) and language certainty (hypothetical vs certain). In an online experiment, we randomised 1523 US adult current smokers and 1391 young adult non-smokers to 1 of 9 conditions following a 2×2×2+1 control design. People reported their comprehension of ‘switching completely’, IQOS risk perceptions and behavioural intentions after message exposure. Results More smokers exposed to MRCs that included an explanation about ‘switching completely’ (22.2%) (vs explanation absent (11.2%) and control (10.7%)) mentioned that ‘switching completely’ meant smoking 0 cigarettes. Compared with the control, several MRCs (eg, certain language) produced lower perceived risk of IQOS, including for diseases not mentioned in the MRCs. MRCs using certain and hypothetical language did not differ on any outcomes. MRCs highlighting reduced risk for a single disease and multiple diseases did not differ on any outcomes. MRCs did not influence behavioural intentions. Conclusion The Food and Drug Administration should ensure that consumers understand what ‘switching completely’ means in an MRC and recognize that some language features may mislead consumers into believing that a product reduces the risk of diseases not mentioned in an MRC.

Introduction Tobacco companies claim that a large proportion of the population perceives potential modified risk tobacco products as equally or more harmful than cigarettes, and argue misperceptions need to be corrected using modified risk claims. However, the studies they cite predominantly use one specific measurement of comparative risk. We analysed a representative sample of US adult smokers and non-smokers to examine whether the proportion who report e-cigarettes as less harmful than regular cigarettes differs depending on how the comparative risk questions were presented. Methods We analysed data from the 2017 Tobacco Products and Risk Perceptions Survey. Comparative risk of cigarettes and e-cigarettes was measured in two ways: direct (single question) and indirect (by measuring perceived risk of both in separate questions and then subtracting the scores from each other). Results When asked to compare harms of e-cigarettes and cigarettes directly (single question), 33.9% of participants identified e-cigarettes as less harmful than cigarettes, 36.4% reported equal harm, 4.3% said e-cigarettes were more harmful and 25.3% said ‘I don’t know’. When asked indirectly (separate questions), 42.1% identified e-cigarettes as less harmful than cigarettes, 23.8% said they were of equal harm, 7.1% perceived e-cigarettes to be more harmful and 27.1% did not know. Conclusion Our study offers evidence to suggest the need to use both direct and indirect risk questions when assessing the public’s perceptions of harms associated with novel tobacco products.