Twitter messages (ie, tweets) consist of brief text (up to 280 characters and emojis) with media and links. Due to the brevity and richness of tweets, and the popularity of the Twitter platform in the United States [30], several studies have used Twitter data for surveillance of public perception of tobacco-related topics [16,20,23,31-34]. We used a mixed-methods study design to assess the quantitative breadth and qualitative depth of tweets related to the federal Tobacco 21 policy. We identified tweets during this time frame due to the public attention to this issue during the last months leading up to the enactment of the federal Tobacco 21 law, approved by congress and signed by the US president on December 20, 2019.

Data were collected using the Real-Time Infoveillance of Twitter Health Messages (RITHM) open-source software for Python (Python Software Foundation) [35,36]. The RITHM software was developed by a team of researchers at the University of Pittsburgh beginning in 2014 [35], was released on GitHub in May 2017, and was retired in September 2022 due to changes in Twitter’s application programming interface. While RITHM was actively running on our institutional data server, we were able to collect all publicly available tweets that included specific keywords in their text. For this study, we obtained tweets matching tobacco-related keywords (ie, tobacco, nicotine, cigarette, cigarettes, e-cigarette, e-cigarettes, vaping, vape, vapes, vaper, vapers, vaped, ecig, ecigs, e-cigs, e-cigs, cig, and cigs) [35]. To narrow our temporal focus to a time frame where the Tobacco 21 legislation was garnering public attention, we initiated data collection on September 4, 2019, and continued through the end of the calendar year. Data collection was relatively stable over this time, with the exception of December 7-13, when the data server was offline for maintenance. We then filtered by keywords relevant to the Tobacco 21 policy (ie, 18, 21, age, buy, mcconnell, mitch, purchase, t21, and tobacco21). Some tweets were included due to time-sensitive topics, such as the name of Senate Majority Leader Mitch McConnell (a Republican from Kentucky) because he championed the first Tobacco 21 bill filed in 2019. The original search found 615,574 tweets matched with the search terms. After removing retweets (ie, resharing of existing tweets), this sample was reduced to 231,447 unique tweets. Prior Twitter-based studies recommend methods of reducing the sample to a feasible number for analysis while maintaining integrity of the data that include randomly selecting tweets or stratifying data from a 1%-5% sample [31,35]. For this study, a random 2% subsample (n=4628) of unique tweets, stratified by frequency of tweets per day, was selected based on a reasonable number of tweets for human annotation.

Using a deductive coding procedure, 2 independent coders (initials redacted) were trained by a senior researcher (initials redacted) to categorize tweets according to variables identified in prior Twitter-related studies: relevance, news, and sentiment. For this study, relevance was operationalized as tweets related to the federal Tobacco 21 policy by removing tweets that referenced a state or local law, and news was operationalized as messages that originated from a news outlet or related to a news story. Tweets identified as discussion about a state or local Tobacco 21 policy were coded as such and labeled to not be relevant for this analysis due to varying themes that focused on policy provisions not including in the federal law (eg, military exemptions, preemption, and grandfathering). Sentiment was categorized as messages with either generally favorable (pro), unfavorable (anti), or neither (neutral) opinions of the Tobacco 21 policy; operational definitions have been cited elsewhere [37]. Sentiment context derived from both text and images (eg, emojis, pictures, memes, and videos) portrayed in the tweet; thus, coders were provided a link to the original tweet to review all visual context and links to external sources (eg, news articles) when applicable.

Coders were provided with the tweet text, a link to the web-based version of each tweet, and if the tweet was in response to another account’s tweet, this tweet was provided as well. Using this information, coders were trained to identify tweets relevant to Tobacco 21 policies using an iterative process of coding 200 tweets during week 1 and 500 additional tweets during weeks 2 through 9. Using Cohen κ as a measure of inter-rater agreement [38], which indicates the proportion of agreement after accounting for chance agreement, coders had strong (κ>0.80) for all variables after the fourth week of coding (κ values ranged from 0.855 to 0.982). Data had been used in prior research [25,26]; however, they were annotated by separate researchers using an updated codebook.

As conducted in prior social media–based mixed methods research [31], the qualitative breadth of data were explored using a phenomenological process that acknowledges the research teams’ subjective and preconceived bias while expanding meaning from smaller codes to a broader understanding of the data [39]. After all data were coded, the 2 coders and senior researcher (lead author) met to compare notes about emergent themes, or similar ideas that emerged from the data [40]. For example, all pro-, anti-, and neutral policy tweets were reviewed, and using a thematic analysis, themes per sentiment category were identified. Once the research team came to consensus on themes and representative tweets, a thematic narrative was contextualized to explain the quantitative results. The narrative was also used to update the operational definitions in the codebook, and all data were recoded to total frequencies of identified themes. Coders indicated strong agreement for the emergent themes (κ values ranged from 0.861 to 0.960). Representative tweets were included in Table 1, and paraphrased tweets and aggregated context were reported to protect Twitter users’ identities, as advised by prior research [41].

Once coded, data were explored via descriptive statistics using R statistical software (R Core Team) and trends were visualized using the ggplot2 package. Frequencies of tweets were first assessed per day of the week, to examine if Twitter discussions about Tobacco 21 occurred more often on certain days of the week. Next, frequencies of the tweets coded as pro-, anti-, and neutral policy were reported to determine the most common sentiment tone. Finally, the temporal trends of tweets about Tobacco 21 were examined using timestamps and tweet content to explore trends in social media communication about this policy leading up to the enactment of the federal law.

Twitter data have been noted for their optimal ability to be used for mixed methods analyses due to the quantity of data that allow for the quantitative exploration of depth while also providing a qualitative content analysis, enhancing the breadth of understanding about a topic [31]. The distinction between mixed methods, as opposed to the use of multiple methods, is the point of convergence, or the integration of the 2 methodologies [42]. In prior research that leveraged social media to explore vaping-related topics, data were integrated throughout the analysis process, with emphasis quantifying the phenomenological context of Twitter data [31]. For this study, we used a similar convergent parallel approach due to the phenomenological approach of exploring a particular topic “sentiment toward Tobacco 21” on Twitter. Thus, the qualitative research was first contextualized into codes, and then the codes were quantified for analysis. Finally, the researchers reintegrated the findings by exploring the narrative that helped to explain the context of Tobacco 21 discussions during times where Twitter chatter peaked.

This was an observational study of public discussion about Tobacco 21 on the Twitter social media platform, exempt by the University of Arkansas institutional review board (protocol # 2203394304).

Of the 4628 tweets from the 2% subsample, 1301 (28.1%) tweets discussed Tobacco 21 specifically. Unrelated tweets were often in response to a tweet about Tobacco 21; however, sentiment was coded based on the most immediate tweet. Among tweets relevant to Tobacco 21, 1113 (85.5%) were relevant to the federal Tobacco 21 law, meaning that no state or local law was mentioned in the tweet. Tweets about Tobacco 21 appeared to be posted most frequently on Saturdays and Fridays (Figure 1); the federal Tobacco 21 policy was enacted on Friday, December 20, 2019.

Among the Tobacco 21 tweets, 167 (15%) were supportive of the policy (Figure 2). Themes that emerged from propolicy codes explained that the law represented sensible regulation and protected youth and young adults. Comments from those whose tweets indicated that they vaped and supported vaping endorsed Tobacco 21 as a compromise compared to a complete ban of all vaping products or to flavored vaping products, a regulatory approach feared by some. Some indicated support for Tobacco 21 as a balanced regulatory measure they believed would both reduce youth initiation while also allowing adults to access vaping products. These comments often used phrases that included the word “protection” when describing tobacco and youth. Also, many of these posts provided recommended measures, such as limiting vaping products to vaping or tobacco only stores, raising the MLSA, and limiting nicotine concentrations to <24 mg.

Overall, 432 (38.8%) tweets clearly opposed the policy (Figure 2). Themes that emerged from the tweets coded as antipolicy included discussions about addiction among those aged 18-20 years and doubt that the policy would reduce smoking. Some discussed repercussions for nicotine-dependent young adults should the law be passed, such as tweets that implied humor (eg, used lol) about youth audiences experiencing addiction withdrawals or listed people who might purchase tobacco products for the person underage (eg, parents, friends, and strangers). Other antipolicy sentiments cast doubt that the policy would reduce smoking or included sarcastic remarks criticizing the unimportance of the issue.

Overall, 46.2% (n=514) of tweets about the federal Tobacco 21 law were coded as neutral policy, indicating that the tweet was informative rather than opinionated, or that the tone of the tweet was unclear. Many neutral comments connected the Tobacco 21 law to a government entity, political party, or figure. Political party discussion included party affiliations for both democrats and republicans, and many neutral tweets mentioned President Donald Trump explicitly (n=131, 25.5%). Overall, 194 (17.4%) of the federal Tobacco 21 tweets were coded as being reported by a news source or in response to a news article. Most news-related tweets (n=179, 92.3%) were coded as neutral policy. Another emergent theme from neutral tweets was the description of methods of circumventing the law, such as implying that those who were under the MLSA would ask those over 21 to purchase tobacco products for them. After data were recoded, we discovered this theme included mixed sentiment, with 26 tweets representing neutral sentiment (acknowledgement of methods to avoid the law while not implying their policy position) and 42 tweets representing negative sentiment.

News articles about a potential federal Tobacco 21 policy surfaced on Twitter as early as September 9, 2020 (or earlier but outside the data collection window); however, most discussion happened around the time the policy was signed into law (Figure 3). Temporal trends indicated that most news-related tweets coded in this subset of data generated little discussion about Tobacco 21 in the months leading up to enactment. Most Twitter discussion generated from news and general discussion emerged in the final days before enactment.

We explored Twitter sentiment and temporal trends of discussions about Tobacco 21 leading up to the enactment of the federal law. While Twitter has been used in the past to explore miscommunication about Tobacco 21 [25] and connections to other age-related behaviors [26], our study is unique in its mixed-methods exploration of sentiment about Tobacco 21. We found most tweets about the federal Tobacco 21 law, leading up to its enactment in the United States, were either neutral or antipolicy. These findings contrast those of polling studies conducted prior to 2018 [8-11], when many states and localities began passing their respective ordinances and laws.

Data collected from social media networks (eg, Twitter) have been used in prior research to explore a wide range of health topics including vaccinations [43,44], dementia [45], and use of novel tobacco products such as e-cigarettes [20,37,46]. For example, a text-mining study regarding the announcement of the Deeming Act of the Food and Drug Administration (FDA) found many of the 4629 tweets made during or before enactment were not supportive of the FDA’s regulatory authority of e-cigarettes [23]. Consistent with this, over one-third of tweets from our study expressed disapproval of the federal Tobacco 21 law. Some of these tweets suggested the law may increase illegal behavior, such as using fake identification, by those addicted to nicotine. Understanding this sentiment and the concern for young people’s need to engage in illegal behavior emphasizes the importance of cessation programs for young audiences who are dependent on e-cigarettes [47-50]. Some antipolicy tweets cast doubt on the efficacy or importance of the law used using sarcasm. While this context can be difficult for coders to capture, it was a strength of our study that we used human annotation, given the challenges of training algorithms to do this [29].

Among neutral discussions about Tobacco 21 on Twitter emerged themes that included news articles that discussed the law and references to political figures, parties, and government affiliation. Many of these tweets appeared to be a call to action to the US president at the time; however, the legislative process for amending the federal MLSA relied on an act of congress before the president could sign the law. This may suggest that government agencies could provide education to the public about the regulatory processes or limitations of these agencies (ie, FDA) or people (ie, president) for certain regulatory actions (eg, raising the MLSA vs restricting the sale of flavored tobacco products).

Twitter discussions that supported Tobacco 21 believed it represented a balanced approach to sensible tobacco regulation. This theme framed Tobacco 21 as a better approach than a total ban of all e-cigarette products or on e-cigarette flavors, which was feared among e-cigarette users and vape shop owners during the 2019 e-cigarette and vaping related lung injuries (EVALI) outbreak in the United States [51,52]. This provides more context for policy support consistent with polling studies that suggested most youth, young adults, cigarette users, and adults supported Tobacco 21 laws [8-11,53]. Given that disinformation about Tobacco 21 on Twitter described it incorrectly to be a purchase law (penalizes youth purchasers) instead of correctly as a sales law (penalized retailers) [25], education for retailers and the general public could capitalize on the vaping communities’ policy support by describing it as a well-balanced regulatory approach while also ensuring retailers’ liability for tobacco sales. Further, we found prosentiment to include text that described protecting youth and young adults. This context may have been particularly important for California voters reading public sentiment on social media, provided that Twitter discussions supporting California’s tobacco tax (that ultimately failed to pass a public vote) was criticized for not connecting the issue to young audiences [24]. Although we only found this sentiment reflected in 46 (4%) of the annotated tweets, similar to this previous study about California’s policy initiative [24], messages about Tobacco 21 may have been easier to connect to youth than a tax on tobacco products.

During a similar time frame as our study, news posts about the EVALI were increasing, which have been associated with a concurrent search for e-cigarette cessation resources [54]. Our search indicated small peaks of discussions about Tobacco 21 that occurred around the same time of the news articles about EVALI (September and November) [54]; however, most discussion about the policy occurred on Twitter around the time the law was passed. Thus, the public may have been distracted by broader conversations about the future of e-cigarettes during the EVALI outbreak and may not have been aware of the political movement for this particular legislation. This awareness is important to understand to inform implementation, enforcement, and communication after such laws are enacted. Lack of awareness about this law would suggest a need for an educational campaign and training for retailers and the public alike. Implementation scientists could examine how Tobacco 21 was rolled out to state and local agencies, along with retailers and general public awareness and compliance with the federal law. Moreover, understanding public response also may be of particular interest to policymakers in other countries currently considering raising their legal sales age of tobacco [55].

Prior research has examined cyclical trends for illness (eg, strokes occur most commonly on Mondays) [56] and smoking cessation seeking behaviors (eg, there are 25% more internet searchers for cessation resources on Mondays than all other days of the week combined) [57]. Understanding weekly rhythms of web-based discussions about policies can inform best times to post information about a health topic or respond to Twitter chatter discussing a policy. We found most tweets were posted on Fridays and Saturdays, which differ from the rhythm cycles of other health discussions [56,57]. This may be a response to news generated later in the week, or this timing could be attributed to the enactment of the Tobacco 21 law. Congress passed the bill (H.R. 1865) on Thursday, December 19 and the president signed the bill into law on Friday, December 20, 2020. Thus, research examining time-stamped discussions about the legislative progress of the bills should consider that such data could demonstrate a 1-day delay.

Twitter provides an open platform for public opinion. Therefore, it may capture a vocal audience that does not precisely represent US demographics. Further, search terms used to identify tweets relevant policy evolve over time as public discussion changes. For example, we used McConnell as a search term due to Mitch McConnell’s involvement with the first Tobacco 21 bill proposed to the Senate; however, it is unlikely that the name would remain a key search term after the enactment of the policy. Thus, those seeking to explore discussions about Tobacco 21 after enactment of the federal law should consider search terms relevant to the law during the time frame they are exploring. Another limitation of our study was that only 1301 (28.1%) of the identified tweets were relevant to the discussion. There was substantial discussion about tobacco products during the time the data for this analysis were collected [54]. This may have generated broad discussion about tobacco products that included necessary search terms for our data collection but unfortunately captured Twitter chatter that did not discuss Tobacco 21 specifically. An unanticipated disruption of the RITHM data server occurred in our final month of data collection and lasted about a week. Rather than terminating the study early, we maintained consistency with the original research protocol and reengaged with data collection through the 18 remaining days of the calendar year. This nonetheless remains a limitation of our study and may have had a marginal impact on our findings. Further, some tobacco-related policy discussions may include mixed sentiment, which was not annotated in this study but was identified following annotation. Given the complexity of public discussion about tobacco control policies, we recommend for future social media–based research about regulatory processes, capture mixed sentiment as well as sentiment subcategories, such as sarcasm.

Social media–based research may help complement traditional methodologies in identifying awareness of and support for or against tobacco control laws and communities’ readiness for such laws. Further, this research methodology may help researchers provide policymakers with timely and meaningful recommendations for further policy amendments or educational practices. As tobacco access laws (eg, legal sales age and flavor restrictions) are introduced, it will be important to understand communities’ acceptance of such laws to ensure that they are implemented and enforced as intended. Given that most discussion about Tobacco 21 occurred in the final days of enactment, tobacco regulatory agencies should allocate resources for education and compliance for retailers and the public about the law to help address enforcement challenges.