Public health agencies’ use of social media for communication during pandemics: a scoping review of the literature

Search Strategy and Selection

We searched 7 bibliographic databases (Sociological Abstracts, Medline, PsycInfo, Scopus, Health Business Elite, Health Policy Reference Centre, and Embase) for relevant peer-reviewed publications. These databases encompass reference sources for biomedical research, behavioral and sociological research, healthcare administration and policy issues, and related fields of interest. For grey literature searches, we consulted 5 sources: Bielefeld Academic Search Engine (BASE), WHO’s Institutional Repository for Information Sharing (IRIS), and the .gov.au and .edu.au domains of the Google platform (each search limited to the first 5 pages).

We developed the search terms based on our research aim and in consultation with a healthcare specialist university research librarian, using the Sample-Phenomenon-of-Interest-Design-Evaluation-Research-type (SPIDER) framework [32]. We defined our sample (population of interest) as publicly funded health agencies at all levels of governance, and the phenomenon of interest as social media communication of public health messages during a pandemic. The design described the research methodologies used, while the evaluation focused on how members of the public engaged with and utilized the public health messages.

Following this process, we selected 3 key search terms: “social media”, “healthcare communication”, and “pandemic management”. We then subjected the search terms to explosion and critical evaluation using Medical Subject Headings (MeSH) to generate keywords for the search strategy. Finally, we employed the resulting keywords for each database search. An example is provided in Table 2.

Table 2.

Example of search strategy: Sociological Abstracts

Inclusion and Exclusion Criteria

The SPIDER framework facilitated the process of determining inclusion and exclusion criteria [32]. First, key search terms were defined. “Social media” referred to online platforms that utilize Web 2.0 technology to enable the creation and exchange of user-generated content across a variety of communication activities, supporting user interactions [1]. “Health communication” pertained to the dissemination of health messages aimed at influencing behavior change within the realm of health [33]. A “pandemic” was characterized as an emerging infectious disease with rapid international spread among humans, where no prior immunity existed [4]. Out of the 6 diseases declared as PHEICs in the past 20 years, poliomyelitis and monkeypox were excluded. These diseases did not meet the definition of a pandemic, as they were not new at the time of the outbreak and had existing vaccines [7,34,35]. The remaining 4 diseases—coronavirus disease 2019 (COVID-19), Ebola, H1N1 influenza, and Zika—met the definition of a pandemic. Middle East respiratory syndrome and severe acute respiratory syndrome (SARS) were also included in our list, despite not being declared as PHEICs by the WHO [7], because they met the definition of a pandemic (Table 1) [4]. The SARS outbreak occurred before the 2007 revision of the International Health Regulations by the WHO and the introduction of the “PHEIC” term [5]. Thus, the WHO termed SARS “a worldwide health threat” [36].

After finalizing our definitions, we established the following inclusion criteria: full-text publications in English, evaluations of health messages from PHAs posted on their social media accounts focusing on acute communicable diseases of pandemic proportions, and publications between January 2003 and August 2022. Our initial database searches yielded 4,208 non-duplicated papers. After applying the inclusion and exclusion criteria, 73 eligible papers were selected for the scoping review. The first author conducted the stepwise process, while the other 4 authors reviewed each step and addressed discrepancies. Figure 1 presents the flowchart in accordance with the PRISMA-ScR guidelines [31]. The first author served as the primary coder, extracting variables that influenced the effectiveness of PHAs’ health messages on their social media accounts during pandemics from the full text of the 73 eligible papers. These variables were then integrated into sub-themes and further aggregated into themes. The second author independently coded 10% of the studies at random to ensure consistency. All remaining authors reviewed the codes to confirm reliability. Consequently, an iterative approach involving independent work and group discussions was employed to eliminate individual bias and enhance data validity.

Figure 1.

Screening procedure. PRISMA template adapted from Page et al. BMJ 2021;372:n160, according to the Creative Commons license [31].

PRISMA, Preferred Reporting Items for Systematic reviews and Meta-Analyses; BASE, Bielefeld Academic Search Engine; IRIS, Institutional Repository for Information Sharing.

Characteristics of Included Studies

The resulting records included 71 peer-reviewed papers and 2 pieces of grey literature (Figure 1) [31]. Only 25% of the studies were published within the first 10 years of research output (Table 3). The remaining 75% were published in the last 3 years, coinciding with the COVID-19 pandemic. Three other pandemics covered by the studies were Ebola, Zika, and H1N1. The relative number of publications for each pandemic corresponded to the duration of their PHEIC status (Table 1) [4]. The publications originated from 18 countries, with approximately half coming from the United States of America (USA). China, Canada, and Singapore were other significant contributors, while countries from Africa, Europe, Oceania, and South America were less represented. These publications examined the social media public health communication activities of PHAs in 42 countries. The USA was the focus of 32 studies, either partially (n=5) or entirely (n=27), while 27 countries were each the subject of no more than 1 study. The WHO was analyzed in 15 studies, and 12 studies compared multiple countries. Twitter and Facebook were the primary social media sources of research data, with 76% of the studies relying exclusively on one or the other. Twitter was included in all 7 studies that utilized data from multiple social media platforms. Single-method studies, either quantitative (42%) or qualitative (37%), were more common than mixed-method studies (21%). Of the 22 papers analyzed, 30% employed a theoretical framework or approach for their study, with the crisis and emergency risk communication (CERC) model being the most prominent (Table 4) [15,18,27,29,37−54].

Table 3.

Characteristics of the reviewed papers (n=73)

Table 4.

Theoretical frameworks used for social media data analysis

A wide diversity is evident in the volume of social media data used in the studies (Table S1). Some studies analyzed only tens of health messages, while others examined thousands. The health messages studied ranged from low-media-styled posts (plain text) to high-media-styled posts (videos, infographics, and photos). Fifty-seven papers (78%) assessed PHAs at 1 of the following levels: global, national, state, or local (Figure 2). National-level PHAs were the most studied, with 52 papers in total; 38 of these focused solely on that level, and 14 compared them with PHAs belonging to other levels. Local-level PHAs were the least studied, involving 13 papers, 1 fewer than state-level PHAs. Only 4 papers examined PHAs’ social media health messages across all tiers of government in a country. Thirty-one papers studied 1 PHA each, while 42 studied multiple PHAs; 12 of these papers focused on PHAs from multiple countries (Table 5). The United States’ Centers for Disease Control and Prevention was the most studied PHA, followed by the WHO (Table S1). There was also a wide variety in the timeframe of social media data used in the studies (Figure 3). The most prevalent range was 2 to 4 months (28%), followed by 6 to 12 months (22%). Half of all the studies fell between both timeframes. Twenty-one studies (29%) based their timeframes on the period surrounding a PHEIC or national health emergency declaration. The assortment of PHAs studied, pandemics of interest, social media data volume, and data timeframe in the reviewed papers underscore the plurality of researchers’ scope and attention.

Figure 2.

Distribution of the jurisdiction of public health agencies assessed by the reviewed papers.

Table 5.

Jurisdiction of PHAs assessed by the reviewed papers

Figure 3.

Time span of social media data used for analysis.

Variables Influencing PHAs’ Social Media Health Messaging during Pandemics

A total of 20 variables were identified as playing a role in the effectiveness of PHAs’ use of their social media accounts to communicate relevant health messages during pandemics, based on the 73 reviewed studies. These variables were grouped under 6 broad themes: the origin of health information, the topic addressed, the semantics and style of messaging, the timing of messaging, the diversity of platforms and audience profile, and the credibility and reliability of message content (Table 6). The findings are further explained below, followed by a review of implications for practice and future research.

Table 6.

Variables influencing PHAs’ social media health messages during pandemics

Origin of Health Information

Sixty-two selected papers (85%) examined variables related to the reputation, internal players, and strategies of PHAs. Four sub-themes emerged under the sender of health information—namely, the status, tactics, policies, and personnel of PHAs.

The status of having a track record in pandemic management was found to be critical to a PHA’s effectiveness when using social media to communicate health messages during a pandemic [55−59]. PHAs were perceived by the public as high-impact organizations that should serve as the primary source of health information during pandemics [60−62]. To ensure the effectiveness of social media health messages, there must be no ambiguity regarding which PHA in a country or territory is the authorized information source [63]. An absence of ambiguity enabled PHAs to act as agenda-setters on social media for both other PHAs and the public. These agenda-setters occupy strategic network positions, which amplify the reach of their health messages and generate widespread public engagement as other PHAs share the messages with their own followers [25,51]. PHAs that have earned public trust tend to be more effective in disseminating health messages during pandemics than those with a trust deficit [39,64,65]. Not only should PHAs be trustworthy, but they should also actively work to build mutual trust [47].

Nimble tactics also influenced PHAs’ effectiveness. To increase their reach within their jurisdiction, PHAs adopted multilingual health messages [14,15,66]. They also utilized appropriate terminology in their messages [67] and offered advice using culturally fitting strategies [54,68]. PHAs featured diverse personalities as subjects or spokespersons on their social media channels, such as social media influencers [14,40,69], celebrities [70,71], medical personnel [72], political leaders [73], or victims sharing personal experiences [42,72]. Another tactic was “attribution of responsibility,” which negatively labelled non-conforming members of the public [67,74]. At other times, PHAs sometimes opted for “ethical disengagement” [10] as a means of enhancing the effectiveness of its messages. PHAs also collaborated by sharing one another’s health messages [25,51]. The tactics implemented by PHAs enabled them to disseminate their messages to various special populations and target audiences.

In-house social media policies providing guidelines have been shown to influence the characteristics and effectiveness of health messages shared by PHAs during pandemics [49,75]. Policy frameworks for PHAs were helpful in setting goals and strategies, as well as identifying the target audience for its social media health communication. Twenty-nine studies discussed 17 guidelines that PHAs followed to create and share health messages on social media. Among these guidelines, the most prominent focused on emphasizing the transmission of health messages [17,26,69], fostering public interaction and engagement [10,37], and expressing empathy to those directly affected by pandemics [27,29]. PHAs were also encouraged to put risks into proper perspective [12,68], promote transparency of information and efforts [49,65], and be timely [38]. Utilizing multiple social media platforms was found to be valuable in effectively reaching a larger audience [18], while members of the public could be recognized as advocates and partners in the co-creation and dissemination of health messages [49,55]. If necessary, PHAs could discontinue further interaction with any member of the public [10,26]. However, Chen et al. [46] noted that adhering strictly to guidelines without flexibility could hinder effective social media messaging for PHAs.

Nine studies shed light on the impact that the personnel in charge of PHAs’ social media accounts could have on the effectiveness of health messages shared during pandemics. Possessing expertise in areas such as journalism, public information management, or public health was associated with enhanced quality of PHAs’ social media health messages [26,75,76]. These professionals demonstrated a greater aptitude for employing appropriate strategies to develop and distribute content on behalf of PHAs. However, disclosing the identity of these individuals could be detrimental if they have had a negative past with the public [24]. Alongside the personnel’s ability to perform their jobs, emphasis was placed on providing them with the necessary digital tools and equipment [75].

Topical Issues Addressed

Sixty-two selected papers (85%) examined variables related to the general message topics of PHAs. There was considerable diversity in how PHAs framed their social media health messages during pandemics [63,77]. The 6 categories within the subject of messages comprised education, government efforts, collaboration, news updates, misinformation, and supplementary messages.

Education dealt with PHAs’ health messages that aimed to raise public awareness about the risks associated with pandemics [46,53,78]. These messages offered specific insights into disease mechanisms, as well as preventive and safety measures that individuals should adopt [44,79,80]. Public consciousness was heightened regarding pandemic epidemiology, accompanied by recommendations on preventive strategies to prevent both community and hospital transmission [63,72]. This educational approach successfully captured public attention. Topics addressed included the use of personal protective equipment [24,52,63], vaccination and vaccine hesitancy [55,72], lockdowns, isolation, and physical distancing [45,51,73], personal sanitation [68,77], routine immunological testing [41,66], and contact tracing [29,73].

Government efforts to implement public health policies, enhance healthcare delivery, initiate or sponsor epidemiological studies, announce significant scientific breakthroughs, and modify the usual social and economic order comprise another category of health messages [27,29,52,53,59,67,68,77,81−83]. The extent to which this information was communicated impacted the effectiveness of these messages. Regular updates on government actions provided the public with incremental knowledge, offering reassurance during the uncertainties of pandemics [29,71]. These messages reflected the preparedness of governments at all levels [76]. Consequently, the public was eager to discuss and share these messages with other social media users [52,81]. Health messages of this nature maintained high public engagement throughout all stages of a pandemic [27,81,84].

PHAs’ health messages also encouraged active public collaboration in efforts to combat pandemics by soliciting philanthropic donations of personal resources, including time, skills, and funds [50,79,81]. Utilizing local and international collaborations provided the solidarity PHAs needed to drive their narratives [12,44,68]. Other messages expressed appreciation to donors and contributors [37,82], with special mentions for healthcare workers [78,83], and construction workers [29]. PHAs’ tendency to acknowledge the concerted efforts of the public during pandemics influenced the effectiveness of their health messages, as people were more likely to like and share the messages [27].

News updates were identified as another prominent feature of PHAs’ social media health messages [14,78]. These messages aim to inform the public about the changing pandemic indices by providing real-time information on morbidity and mortality cases, as well as other related data [27,56,64] and the latest updates on hospital services [76,82]. Health messages often came in various forms, such as broadcasts of press conferences [37,63,76,81,85]. Framing health messages as news enables the public to gain situational awareness of a pandemic as it unfolds. However, not all PHAs utilized this approach, which may hinder the effectiveness of their health messages within their jurisdiction [76].

PHAs also shared health messages on their social media accounts to combat the spread of misinformation and fake news that incited panic among social media users [18,26,64,86]. They raised the public’s awareness on how to avoid falling for misinformation [14,37] and corrected false information when necessary [10,87]. However, in many cases, inaccurate information from unverifiable sources was disseminated more widely by irresponsible social media users than the accurate health messages provided by PHAs [88]. In some instances, even reliable government sources inadvertently shared incorrect information [12]. The dedication of PHAs to addressing uncertainties and clarifying inaccurate health information played a major role in the effectiveness of their social media messaging during pandemics.

Finally, PHAs also posted messages unrelated to the ongoing pandemic [15,67,83]. Often, PHAs were slow to respond at the beginning of a pandemic, as evidenced by the predominance of non-pandemic messages in their social media communications [48,62,67,88]. However, when compared to messages not related to the pandemic, those addressing the pandemic were read by more people, and readers spent more time engaging with them [37,48,62]. It remains unclear why PHAs hesitated to increase their pandemic-related messaging in response to the public’s growing information needs during outbreaks. It appears that PHAs may be uncertain about what information to share at the onset of pandemics [83].

Structure and Style of Messaging

Fifty-five papers (75%) examined variables that focused on the structure, style, and supplementary elements of the messages of PHAs. The 3 resulting sub-themes were the dialogic tools, media richness, and message tone of PHAs.

Dialogic tools refer to elements incorporated into social media health messages that facilitate engagement and interaction between the sender and the audience [27]. The presence of dialogic tools in PHAs’ health messages influenced the effectiveness of those messages. Hashtags and hyperlinks were the most commonly used dialogic tools by PHAs [39,41,62]. For example, the use of hashtags was associated with higher levels of public engagement while the opposite was true for hyperlinks [15,53]. When both were combined in a post, public engagement levels increased [76]. Health messages featuring multiple dialogic features tended to garner more engagement than those with a single feature [46]. Higher-level PHAs often used hyperlinks to direct their audience to their own websites for more information [41], but state-level PHAs preferred to send their audience to the websites of federal-level PHAs and other reputable organizations [42]. Although PHAs used dialogic tools in various ways, they generally used such tools to collaborate, which in turn reinforced one another’s messages [25,56,63,89]. This approach effectively demonstrated the coherence of the views of different PHAs on the same issue. Other dialogic tools used less frequently by PHAs included the @ mention function, question and exclamation marks, live chats, reply, forward, and quote functions [46,52,53,76,87]. These tools were effective to varying degrees in generating public engagement with health messages. The public’s perception of the effectiveness of health messages is related to the degree to which 2-way communication is accommodated [60,90]. Two-way communication benefitted the public by promoting consensus building and mutual trust [10,27].

Media richness refers to the ability of a message to generate shared meanings and facilitate smooth interactions between the sender and receiver of the message [46]. Generally, health messages with high media richness were less likely to engage users on text-oriented platforms like Twitter and Sina Weibo [46]. However, combining images with plain text can increase public attention [56]. Infographics and pictures were the commonest media enrichment tools used by PHAs [56,68,70]. The current pandemic phase at the time of infographic development influenced their design and layout [91]. Factors such as the choice of background colors, the language used, and the personality presented in the image were all subtle but influential elements of graphics and pictures incorporated into PHAs’ health messages [40,92]. Higher-level PHAs further enriched their health messages (e.g., by using videos) more frequently than lower-level PHAs [92]. As with infographics, PHAs had different options for creative video styles to adopt for their health messages, ranging from animations to live-action videos [63,89]. More creative videos were more effective. Factors such as video duration, tone, and title length significantly influence the effectiveness of health messages in generating public engagement [14,63,84]. However, engagement levels with videos were lower than with plain text on text-oriented social media platforms such as Twitter [15], WeChat [82], and Sina Weibo [46].

The choice of message tone was another sub-theme. As the language used on social media tends to be more similar to spoken communication rather than written, the effectiveness of PHAs’ health messages was related to the extent to which the messages exhibited a conversational tone [38,39,47]. PHAs, however, typically adopted either an authoritative formal tone or an interactive informal tone [47,54]. PHAs were more likely to use a formal tone in their social media messaging when emphasizing guidelines, instructions, and warnings [68]. Although the public often perceived PHAs’ formality negatively as mere grandstanding, certain situations, such as addressing misinformation, made the formal stance non-negotiable [10,18]. Conversely, when informality, cordiality, and humor were incorporated into health messages, public engagement increased with more views and reactions [69]. In the same vein, PHAs may choose to convey positive, negative, or both tones in their messaging. Positive messages tend to focus on solutions, while negative messages can dampen public morale [56,72]. The more positive a health message is, the more engaging it becomes. Message tone also involves communicating emotion-laden cues to which the public responds [67,84]. The emotional valence of PHAs’ health messages influences their effectiveness in triggering public sentiments, emotional support, diffusion, and engagement [58,67,84,93].

Diversity of Platforms and Audience Profile

Fifty selected papers (68%) examined variables related to the reach of PHAs’ health messages to the public, with an emphasis on the subscribers and followers of the social media accounts of PHAs. This theme was consolidated from 2 sub-themes: community and platforms.

During pandemics, the followership of PHAs’ social media channels consistently increased as people sought health messages from authentic sources [18,26,42,57,62]. Higher-level PHAs with broader jurisdictional coverage tended to attract more followers than lower-level PHAs [48]. PHAs established social media accounts on platforms where their target audience was most likely to be found [83,91]. The geographic location of a PHA played a role in distinguishing its audience characteristics from those of other PHAs [10,14,42]. However, each PHA had to contend with diverse audience profiles in terms of demographic features [17,38,39,57,63,64]. PHAs tailored their health messages to specific target audience profiles and social media channels [40,49,56,70,94]. The engagement patterns of the audience also tended to influence subsequent messaging from PHAs [44,48,63,95].

Accessibility to social media platforms within a PHA’s jurisdiction encourages users to engage with the PHA’s social media channels. The most popular social media accounts for PHAs were found on Facebook, followed by Twitter, across various regions and countries, including Anglophone Africa [14], the USA [42,48,57,65,71], Italy [27,70], Canada [38,39,62], New Zealand [27], the United Kingdom [27,71], Denmark, Norway, and Sweden [10], Singapore [71], and for the WHO [55,65]. Twitter provided the most connections to PHAs’ social media accounts in India [73]. Sina Weibo was the most popular in China, followed by TikTok [46,53,82,84]. Despite YouTube’s ubiquity, few users connected with PHAs’ social media accounts on the platform [14,63,89]. Channel popularity did not always correlate with PHA usage. For example, while a large Facebook following prompted health communication by PHAs in Singapore and Macao [49,81], the less popular Twitter was more frequently used by PHAs in the USA [49,57,78,88] and Africa [14]. Nevertheless, PHAs often used multiple platforms to share their health messages [56,85], as each social media platform exhibited unique characteristics [15,81,94] and [14] supported public engagement differently [41,85,94].

Timeliness and Relevance

Forty-nine selected papers (67%) investigated variables associated with the relevance of health messages from PHAs at the time of delivery. This theme encompassed 2 sub-themes: pandemic milestones and phases, as well as message frequency.

PHAs recognized certain milestones or new developments during a pandemic, such as the announcement of a PHEIC, during which health information demand is highest [37,45]. Notwithstanding, while some PHAs posted the preponderance of their pandemic-related health messages around these landmark events [52,60,70,94], others shared a disproportionately small volume of information [42]. When PHAs trended together with pandemic-related events, their health messages were highly effective in attracting public engagement [43,62,71] and generating diverse emotional reactions from the public [67]. Conversely, Madvig et al. [26] and Lwin et al. [29] reported no consistent relationship between PHAs’ health message volume during landmark pandemic-related events and the level of public engagement.

The pandemic phase during which PHAs shared health messages could influence the effectiveness of messaging [81]. Pandemics can be segmented into phases based on the disease progression in the community. However, there was no shared basis for this segmentation in the literature, and the number of phases was presented as 5 [15,29,37], 4 [51,59,81,83] or 3 [65]. Ahmed et al. [79] and Radwan and Mousa [68] restricted the segmentation to the lockdown period only. PHAs’ pandemic-related health messages varied with pandemic phases, irrespective of the segmentation type adopted [15,83]. The volume of messages and the range of topical issues addressed were lowest during the prodromal phase, but rose significantly when the first pandemic cases were reported [14,15,59,63,81,83,88]. However, despite the higher volume of messages, certain population groups were often not targeted [96]. Batova [24] attributed this apparent oversight to PHAs’ limited knowledge about pandemics during the early stages of an outbreak.

Early messaging from PHAs following an outbreak was helpful in guiding the public [41,62], although such messaging was often delayed until a sharp increase in cases occurred [14,76,78]. Frequently, the content of these health messages did not meet the public’s information needs [59,80,83], which evolved with the different phases of the pandemic [29]. There were instances when the messaging from PHAs did not align with the rate of disease spread, rendering the messages less relevant to the audience [88,97]. Within the same pandemic phase, individual PHAs shared health messages on topics they deemed appropriate [79] or established common ground with other PHAs [51]. The posting of conflicting messages from different PHAs was widespread during the early phases of pandemics, but coherence and collaboration gradually became more evident as pandemics progressed [77]. With social media, PHAs could communicate at the public’s most preferred times of the day [64,76,98], resulting in a wider reach for well-timed communication strategies. Similarly, maintaining a regular frequency of health messaging [37,56] allowed the public to build trust and confidence in the activities of PHAs.

Content Credibility and Reliability

Forty-five selected papers (62%) investigated variables related to the credibility and reliability of health messages conveyed by PHAs. Within these studies, 3 sub-themes were identified: congruence, transparency, and consistency of the messages.

Congruence refers to the extent to which PHAs display consistency in content and context within their pandemic-related health messages. This is particularly crucial for PHAs operating within the same jurisdiction or catering to the same audience. Incongruence among PHAs is not uncommon during pandemics, as situations continually evolve [65,77,91]. Instances of incongruence have been observed in message volume, the selection of topics addressed, and the timeliness of addressing issues by different PHAs [14,27,40,47,65,79,89,95−98]. For example, PHAs’ health messages addressed misinformation differently during the COVID-19 pandemic [71]. Incongruence can lead to varying levels of public emotional diffusion across PHAs [93]. Dissonance among PHAs negatively affects the public’s response to conflicting health messages, while congruence has the opposite effect [77]. Sharing health messages with similar themes at comparable times and frequencies, as well as referencing one another, indicated coordination and collaboration among PHAs [25,51].

Health messages from PHAs could be perceived to be insufficiently transparent and objective [74,91]. The transparency of PHAs was called into question when they faced a deficit in public trust, as evidenced by fear-inducing health messages that suggested hidden motives related to financial gain, corruption, conspiracy [24,58,60,85] or political interference [26]. Health messages that are perceived as non-transparent often prompt public responses calling for PHAs to be more forthright. However, message transparency could be hindered by the public’s level of scientific literacy [72]. The public frequently associates transparency with the jurisdictional level of PHAs [50,53]. Nevertheless, PHAs at all levels have the potential to exhibit transparency, which can influence the effectiveness of their pandemic-related health messages [98].

The consistency of opinions expressed in PHAs’ pandemic-related health messages was another influential factor. Perceived inconsistency diminished the relevance of PHAs’ health messages to the public [18,24,26,39,77]. Inconsistency and ambiguity in PHAs’ communication of pandemic-related risks arose when successive health messages continually shifted, leading to public anger and criticism [18,24,77,86]. This caused some individuals to become more anxious, while others downplayed the risks [48]. Since PHAs’ health messages did not consistently address the public’s concerns, the resulting demand-supply mismatch undermined the effectiveness of their health messages [37,47,59,80,83].

Contribution to Theory and Practice

The grounding of public health communication science and practice in social media theory is still in its early stages. This literature review discovered that only 22 studies (30%) employed a theoretical approach or framework for critical data analysis. Thirteen distinct theoretical frameworks were utilized, with the CERC model being the most prominent. The variety of theories applied indicates that they are still being tested in health communication research. This finding supports the arguments made by Hannawa et al. [99] and Hannawa et al. [100], who posited that empirical research in health communication lacked theoretical rigor and a clear epistemological approach, which are 2 essential components for framing practical solutions in the field.

Only 1 study, by Vijaykumar et al. [49], discussed a framework. This framework, risk amplification through media spread (RAMS), was conceptualized as a potential tool to guide future public health communication activities of PHAs during pandemics. However, the framework was designed for the entire health communication spectrum, not social media only. Liu and Kim [67] called for further investigation into viable communication frameworks during pandemics. Pandemics and their associated effects typically last longer than most crises, which tend to be acute and have a more limited geographical spread. Conversely, Vijaykumar et al. [49] emphasized the importance of evaluating the ways in which social media efforts impact societal behavior during pandemics. It is not enough for PHAs to simply post health messages on social media; the influence on societal behavior should also be monitored and measured. This literature review proposes a conceptual model (Figure 4) that could serve as a foundation for additional research into social media health communication by PHAs during a pandemic.

Research Gaps: Directions for Future Research

Each successive pandemic of the 21st century has increasingly exposed the gaps in social media health messaging by PHAs [14]. The year 2003 marked the beginning of the social media revolution as we know it today [3]. SARS, the first pandemic recorded in the social media era [2], occurred the same year [36]. This scoping review found no evidence that any PHA used social media platforms for relevant communication during SARS. As social media was still in its infancy [3], PHAs would not have considered it as an option for their public health communication. The next pandemic, H1N1 [5,7], presented a different narrative. Three studies [49,67,75] revealed that PHAs utilized their social media channels to communicate pertinent health messages about the pandemic. However, these studies focused solely on the USA. By the time of the most recent pandemic, COVID-19, studies have covered 42 countries to varying extents (Table 3). Consequently, there is a gap in knowledge about the situation in many countries during a pandemic. Likewise, there are gaps in understanding how social media platforms can be effectively used. This literature review identified 7 social media platforms that were used for study purposes. However, there are over a hundred other social media platforms where the public gathers and health communication circulates. PHAs cannot afford to overlook such platforms.