COVID-19 Vaccine Communications on Instagram and Vaccine Uptake in Young Adults: A Content Assessment and Public Engagement Analysis

In Canada, during the pandemic, young adults (18–29 year-olds) represented one of the least-vaccinated age groups against COVID-19. These low vaccination rates, and high infection rates, left young people vulnerable to severe infections and created a risk for transmission to immunocompromised populations. Given young adults’ unique characteristics, to encourage vaccination among this demographic, public health and government officials must adopt an audience-centred approach to communication. We sought to understand if the vaccine messages from 8 Canadian federal government Instagram accounts met the needs of young adults based two frameworks: Guiding Principles for Crisis Communication (compassion and empathy, conversational tone, transparency, clarity, call to action and correction of misinformation), and the 5C Model for Vaccine Hesitancy (confidence, complacency, constraints, collective responsibility, and risk calculation). Across 159 posts that mentioned COVID-19 vaccines, there was limited incorporation of best practices, suggesting the government’s communication strategy did not meet the needs of young people.


Introduction
The development and rollout of COVID-19 vaccinations has been essential for reducing morbidity and mortality from COVID-19 infections; however, this global vaccination campaign has raised unique concerns contributing to an increase in vaccine hesitancy (Danchin & Buttery, 2021).Vaccine hesitancy is a general reluctance or refusal to get vaccinated despite having access to safe and effective vaccines (MacDonald, 2015).Some commonly cited reasons for COVID-19 vaccine hesitancy included the speed of vaccine development (Danchin & Buttery, 2021;Statistics Canada, 2021), the novel mRNA technology used in some COVID-19 vaccines (Adams et al., 2021;Danchin & Buttery, 2021;Dolgin, 2021), and the risk of rare but serious side-effects (Danchin & Buttery, 2021).
In Canada, young adults represented one of the most hesitant subgroups for COVID-19 vaccinations (Public Health Agency of Canada, 2022b).For optimal protection against COVID-19, remaining up-to-date with booster doses has been strongly recommended, however, during the third and fourth waves, young adults made up most of the cases (Public Health Agency of Canada, 2022a) and two-dose (86%) and threedose (35%) vaccine coverage was lowest among 18 to 29 yearolds compared to all other adult age groups (Public Health Agency of Canada, 2022b).This low coverage is a cause for concern, as these vaccines are essential for preventing severe illness, hospitalization, and death among elderly and immunocompromised populations (Wünsch et al., 2022).To protect these groups from life-threatening COVID-19 infections, vaccine campaigns require a high uptake, even among young, healthy individuals (McDermott, 2021).This concept, known as herd immunity, refers to the public vaccination threshold needed to reach population-level protection against a virus, and is a very important public health target to strive toward (McDermott, 2021).
To address vaccine hesitancy and improve vaccine uptake in young adults, government officials must tailor their communications and build public trust through effective communication strategies (The Organization for Economic Cooperation and Development [OECD], 2021).During the pandemic, the Canadian Federal Government was responsible for key public health decisions like vaccine approval, procurement, and distribution.The responsibility to transparently communicate about these decisions, which is a key guiding principle of crisis communication (Centers for Disease Control and Prevention, 2018;Mackay et al., 2022aMackay et al., , 2022b)), fell on government officials-including political party leaders, members of the official opposition, government organizations and public health officials.These federal actors communicated in the form of press briefings, news releases and interviews (Lowe et al., 2022), as well as leveraging social media (Kada et al., 2022;MacKay et al., 2022c) platforms to deliver information.
In times of crisis, public health officials and political actors should be working together to build the public's trust and confidence in public health and policy decisions (Hunter, 2016).Elected and public health officials have a joint responsibility to keep their constituents healthy, so to maximize success and improve the public's health, a strong and coordinated partnership between these groups during crises is necessary (Hunter, 2016).Therefore, in the context of the COVID-19 pandemic, it is important to understand whether the Canadian Federal Government's approach to communicating about vaccines with the public was effective, including examining their communication for best practices and theory known to demonstrate trustworthiness and impact vaccine decision making.

Communication Strategies to Address Vaccine Hesitancy
When communicating about vaccines during a pandemic, federal actors should adhere to crisis communication best practices and meet the needs of vaccine-hesitant individuals (MacDonald, 2015).Two theoretical frameworks -Guiding Principles for Crisis Communication, and the 5Cs Model for Vaccine Hesitancycan be used to address young adults' hesitancies and could ultimately enhance COVID-19 vaccine uptake (Andrews et al., 2020;Henderson et al., 2020;MacKay, Colangeli, Thaivalappil, et al., 2022b;World Health Organization, 2017).
Effective crisis communication is audience-centred and coordinated among officials (Andrews et al., 2020;Henderson et al., 2020); puts the health of the community first (Henry, 2018); provides honest, timely and accurate information (Henry, 2018); reflects the values and needs of communities in co-created messages (World Health Organization, 2017); and ultimately creates and maintains public trust (Henderson et al., 2020).An extensive literature review on best practices for crisis communication on social media has identified the following guiding principles for crisis communication: call to action, clarity, compassion and empathy, conversational tone, correction of misinformation and transparency (Table 1) (MacKay, Colangeli, Thaivalappil, et al., 2022b;MacKay et al., 2021).This consolidated list of guiding principles was informed by key public health sources including the WHO, Public Health Agency of Canada (PHAC) and Centres for Disease Control (CDC) Crisis and Emergency Risk Communication (CERC) guide (Centers for Disease Control and Prevention, 2018).The guiding principles have been used to evaluate social media crisis communications and exhibit a framework for best practices (MacKay et al., 2022b;MacKay et al., 2021).
The "5Cs" model of vaccine hesitancy was designed to understand the predictors of vaccine hesitancy and acceptance (Betsch et al., 2018).The model condenses several psychological antecedents of vaccine hesitancy into the following five predictors: confidence, complacency, constraints, risk calculation and collective responsibility (Betsch et al., 2018) (Table 2).In general, hesitant individuals exhibit all or some of the 5Cs (Betsch et al., 2018) and public health messages to promote the uptake of vaccines should address these factors (Public Health Agency of Statistics Canada, 2021).As such, some studies have aimed to identify the impacts of the 5Cs on decisions to get vaccinated among various groups (Machida et al., 2021;Thier et al., 2022;Wismans et al., 2021), suggesting that COVID-19 vaccine communication must be tailored meet the varying needs of target audiences.

Audience-Centred Vaccine Communication
While these frameworks cover some best practices for vaccine and crisis communication, there is no one-size-fits-all approach to vaccine communication.Instead, the success of a vaccine communication campaign is dependent on whether the needs of the target audience have been met (Brunson et al., 2021;Pent ¸a & Bȃban, 2018).The National Academies of Science, Engineering and Medicine's (NASEM) guidance document on COVID-19 vaccines highlights the importance of trust-building messages designed based on the needs of the target audience, recommending that data from qualitative studies be used to develop audience-centred messages (Brunson et al., 2021).Therefore, the specific needs and priorities of young adults should be incorporated into messages to encourage them to get vaccinated.
Although there is limited research on communicating about vaccines effectively with young adults, a recent study on the 5C preferences of young adults found that collective responsibility and confidence were primary factors that influenced vaccine intention in this age group (Wismans et al., 2021).In addition, young adults have exhibited hesitancies to get vaccinated due to a low perceived risk from the virus (i.e., complacency), and as such communication that target complacency can shift perspectives (Adams et al., 2021).
In addition to previous literature, one must also consider the unique characteristics of the life-stage of their target audience.Young adults, for instance, are in a highly malleable period of growth and development.During this phase, they are faced with social comparison, and their decision making is highly influenced by their peers (Halpern-Felsher et al., 2016).However, by this age, young adults have reached a level of maturity in terms of decision making and have the ability to recognize and weigh the risks associated with decisions (Halpern-Felsher et al., 2016).This life stage is marked with an increase in medical autonomy (Halpern-Felsher et al., 2016), which makes this group an important one to target with health education campaginsincluding topics like vaccination.

Reaching Young Adults through Instagram
Young adults are a dominant user group on social media and in 2020 it was estimated that of the 51% of Canadians that use Instagram, most fall within the 18-34-year-old age group (Gruzd & Mai, 2020).Such platforms provide federal actors with the opportunity to reach a wide audience with their public health messages, and the World Health Organization (WHO) recognizes social media as a mode for facilitating Factors that negatively affect conveniencelike cost, distance, time, and language barriers -can prevent individuals from getting vaccinated • Address barriers to vaccinations and provide solutions to avoid them Include information about psychological barriers (i.e. needle fear) and physical barriers (i.e.limited access to clinics) Risk calculation An individual's ability to compare the risks of vaccinations to the risks of infection and make the decision to get vaccinated.Misinformation and disinformation can greatly reduce willingness to vaccinate • Compare and contrast information about the disease and potential vaccine side effects • Provide information for people to determine risk Provide links to gather further information about vaccines communication, generating awareness, correcting misinformation, and engaging the public during a crisis (World Health Organization, 2017).Previous studies have looked at health seeking behaviour, finding that social networking sites were among the most used online platforms for health seeking behaviour (Lim et al., 2022;Neely et al., 2021;Zhao & Zhang, 2017).The young adult age group is particularly active in seeking health advice on social media (Lim et al., 2022;Prybutok & Ryan, 2015), which make it a good channel for communicating about public health topics like vaccines.Furthermore, a study on university-aged adults found social media platforms as their primary source of COVID-19 information (Chesser et al., 2020).And another study examining young people's interactions on social media during the pandemic found that this age group is most likely to amplify messages that include scientific COVID-19 content with their followers (Volkmer, 2021).These platforms have been widely used during the pandemic to share crisis information with the public (Malik et al., 2021;Neely et al., 2021;Wukich, 2020) and have become a means for evaluating crisis communication and the public's response (MacKay et al., 2022c).Instagram provides the opportunity for the public to engage with posts using the like and comment functions.The like function serves as a measure of positive attitudes towards a post's content, with more post likes representing a more positive attitude (Peter et al., 2014).The comments on a post represent the emotional response of followers and can be used to understand crisis message acceptance and the overall effectiveness of a crisis message (Coombs & Holladay, 2014).A positive sentiment in the comment section is a signal of acceptance of the message whereas a negative sentiment is indicative of a lack of acceptance of the post message (Coombs & Holladay, 2014).
While Instagram engagement demographic data is not publicly available, the known high use by young adults on this platform, along with previous study findings about young adult health seeking behaviour on social media (Chesser et al., 2020;Coombs & Holladay, 2014;Lim et al., 2022;Peter et al., 2014;Volkmer, 2021), strengthens the argument for leveraging social media as a channel for reaching young people with public health information.As such, to meet crisis communication best-practices, government and public health officials must consider their audience based on the platform's primary user group.
The aim of this research was to evaluate the quality and content of COVID-19 vaccine information posted on eight key Canadian federal government Instagram accounts over the first two years of the pandemic, and to answer the following questions:

Inclusion Criteria
Instagram posts that were shared on or after December 31, 2019the date that COVID-19 was first identified in Wuhan, Chinauntil December 31, 2021the height of the Omicron wave, and third-dose rollout in Canadain English, and explicitly mentioned or referred to COVID-19 vaccines (e.g., "get your shot"), were collected from official Canadian federal government, federal public health, and major federal politician accounts.These accounts included: Prime Minister and Liberal Party Leader, @JustinPTrudeau (Justin Trudeau); Conservative Party of Canada Leader, @ErinOTooleMP (Erin O'Toole); New Democratic Party Leader, @JagmeetSingh (Jagmeet Singh); Minister of Health, @PattyHajdu (Patty Hajdu); Green Party Leader, @AnnamiePaul (Annamie Paul); Health Canada's official account, @HealthyCdns (Healthy Canadians); Statistics Canada's official account, @Statcan_eng (StatsCan); and the Canadian Institute for Health Research's official account, @CIHR_IRSC (CIHR).Included politicians held their positions during the data collection period, and if their term ended before the final day of data collection, their successor's Instagram accounts were searched.However, none of the succeeding officials posted about COVID-19 vaccines during their term.Videos, stories, and Instagram Reels were excluded due to the differences in how the receivers interact with the content, how stories and reels are differently displayed (e.g., not directly in the Instagram feed), and their expiration after 24 hours.

Data Collection
Each individual post was given a unique identification label and researchers followed these steps: (1) capture a screenshot of the post image, (2) record a copy of the image caption, (3) record the number of likes and comments (post engagement), and (4) record the date it was posted.Comments and account replies were collected using the online program, Phantom-Buster, which has a feature to automatically scrape Instagram comments from public posts (Phantombuster, Paris, France).Comments were subsequently cleaned to remove duplicates and potential bot comments using Microsoft Excel version 16.62 (Microsoft, Redmond, United States).

Content Analysis
Data analysis was conducted using a qualitative descriptive methodology in which the guiding principles (Table 1) and 5Cs (Table 2) were used to assess the quality and content of crisis communication on Instagram.For a post image or caption to be coded with one of the guiding principles or 5Cs, it had to include at least one of the key features noted in Tables 1 and 2. Images and captions were coded separately to distinguish between the construct use across the two different communication mediums.
After codebook training, two health communication researchers independently coded 10% of the dataset for the guiding principles and 5Cs using NVivo 12 Plus (QSR International, Doncaster, Australia), which is a software that allows qualitative data to be aggregated and analyzed by the researcher.The overall kappa of .67 was found, which shows moderate agreement for inter-coder reliability (McHugh, 2012).Any conflicting codes were resolved through discussion to reach a consensus.The remaining posts were then coded in-tandem by the two researchers and disputes were immediately resolved through discussion.Low kappa was driven by the variables with very sample sizes (i.e.Little to no instances of the guiding principle or 5C in the data) for a number of variables, such as transparency, correction of misinformation, and constraints.

Sentiment Analysis
A sentiment analysis of the comments for each post was conducted using SentiStrength (SentiStrength, n. d.).This program assigns a positive, negative, or neutral sentiment based on the subject matter in each comment (SentiStrength, n. d.).This overall sentiment was found based on a scoring system, which assigns a score to various words and expressions in a text passage (SentiStrength, n. d.).SentiStrength's predefined parameters score common words on a scale of very negative emotion (À5) to very positive emotion (+5) (SentiStrength, n. d.); the program also assigns a neutral sentiment (À1 or +1) to various words.The program then assigns an overall trinary sentiment score of net positive (1), negative (À1) or neutral (0) to the text passage, based on the sum of individual scores of the words found within it.Some of the words' pre-assigned sentiment scores were modified after testing to ensure increased accuracy.Words that had their pre-assigned sentiment scores changed from negative (score of À2 to À5) to neutral (À1) included: death, dying, emergency, ill, infect, isolate, risk, and sick as these words were often used to talk about COVID-19 but not always in a negative context (MacKay et al., 2022c;Thelwall et al., 2010).For example, text that states, "without vaccines, many deaths will occur," speaks positively about vaccines, however, would score negatively in term of sentiment.According to the SentiStrength developer, in highly specific events, especially as one related to health, words may need to be changed to have a neutral score to not falsely influence sentiment (Thelwall et al., 2010).Finally, the program's spelling correction list, booster word list, negating word list, emoticon list, and standard settings were applied.

Engagement Analysis
The average engagement rate for each account was calculated using equation (1) (Le, 2021).Engagement rate shows the interaction of followers with the content each account shares.

Total likesþtotal comments total posts
Number of followers *100 (1)

Data Analysis
Data were collated so that each post was labeled based on its source (i.e., account name) and number of guiding principles and 5Cs used.Engagement metrics (i.e., total number of likes, comments, followers) were collected from each post and included Instagram account.Further, from each account the total number of posts, and total number of comments and their corresponding sentiment scores were reported.

Guiding Principles
In the Instagram post captions, crisis communication guiding principles were used 299 times across all sources (Table 3).Conversational tone was used the most frequently (n = 136), followed by compassion and empathy (n = 57), and clarity (n = 45).Justin Trudeau used the guiding principles most frequently (n = 89) followed by Patty Hajdu (n = 79) and Healthy Canadians (n = 63).Guiding principles were included in 135 post images (Table 4).Of these principles, call to action was the most frequently used (n = 73) followed by conversational tone (n = 23), clarity (n = 22), transparency (n = 15), and correction of misinformation (n = 2).Compassion and empathy were not used in any images.

5C Use Across Accounts
The frequency of addressing the 5Cs of vaccine hesitancy was relatively low across all federal accounts (Table 5).In the post captions, the most frequently addressed factors were collective responsibility (n = 65), confidence (n = 27) and complacency (n = 15).Healthy Canadians utilized the 5Cs the most frequently in their captions (n = 43) followed by Justin Trudeau (n = 28) and Patty Hajdu (n = 25).
In the post images the 5Cs were addressed 99 times across all sources (Table 6).The most frequently addressed predictor was risk calculation (n = 59) followed by confidence (n = 20) and collective responsibility (n = 11).The account Patty Hajdu utilized the 5Cs the most (n = 27), followed by Healthy Canadians (n = 24) and StatsCan (n = 15).

Sentiment
The most frequent overall sentiment among the comments for the federal government's COVID-19 posts was neutral (46.9%,Table 7).Positive comments made up the second largest proportion of total comments (30.7%) followed by negative comments (22.4%).The greatest proportion of positive comments was seen for Annamie Paul's posts (37.1%).The greatest proportion of negative comments was observed for Jagmeet Singh's posts (28.5%).

Discussion
The main findings from our research suggest that COVID-19 vaccine Instagram communication shared by eight key Canadian federal government did not effectively incorporate the

Limited Use of Guiding Principles in COVID-19 Vaccine Messages
The guiding principles for crisis communication aim to build and maintain trust across the population which is important to   improve vaccine acceptance (Andrews et al., 2020;Henderson et al., 2020;MacKay, Colangeli, Thaivalappil, et al., 2022b).However, there was an overall limited use of guiding principles across the Instagram accounts evaluated.Recently published research has determined that throughout the pandemic, online mis-and disinformation has been a driver for COVID-19 vaccine hesitancy and refusal (Garett & Young, 2021;Pierri et al., 2022), demonstrating the need for public access to accurate and trustworthy sources.As a severely underused guiding principle across federal Instagram accounts, correction of misinformation is an essential strategy for reducing COVID-19 vaccine hesitancy among young audiences (Henry, 2018;MacKay, Colangeli, Thaivalappil, et al., 2022b).
Considering additional barriers to vaccine uptake among young adults, transparency and clarity about the development and safety of vaccines is key for encouraging young adults to get vaccinated (Adams et al., 2021), however this principle was one of the least used communication strategies (n = 29).Finally, creating and maintaining trust in crisis communication requires a consistent and unified approach (Andrews et al., 2020;Henderson et al., 2020).The results from our study suggest a consistent messaging approach was not used with respect to the 5Cs and guiding principles.While these guiding principles are important for all crisis communication (MacKay, Colangeli, Thaivalappil, et al., 2022b), utilizing them in Instagram posts is critical for building and maintaining trust, especially among young adults who are active on Instagram (Gruzd & Mai, 2020) and have exhibited some of the most hesitant attitudes towards COVID-19 vaccines (Public Health Agency of Statistics Canada, 2021;Szilagyi et al., 2021).

5Cs Not Widely Incorporated Across Instagram Posts
The limited acknowledgement of the 5Cs across the federal COVID-19 vaccine Instagram communications is concerning as such omissions can fuel vaccine hesitancy (Betsch et al., 2018).While the research is limited on vaccine communication strategies among young adults, this demographic's priorities can be assigned to the various 5C categories to provide evidence-based communication that address the causes of hesitancy.Communication about vaccines with young adults should prioritize confidence, collective responsibility and complacency above the other 5Cs (Adams et al., 2021;MacDougall et al., 2015;Wismans et al., 2021).However, our results found that federal accounts heavily prioritized collective responsibility above all others (n = 65).Finally, some research also suggests that logistical constraints may lead to low vaccine uptake (MacDougall et al., 2015), however crisis information to overcome this was rarely provided (n = 5).
Young adults have had some of the lowest COVID-19 vaccination rates across Canada (Public Health Agency of Canada, 2022b), thus addressing their specific concerns is very important.This age group uses Instagram more than any other adult demographic (Gruzd & Mai, 2020) and federal accounts can leverage the 5Cs by applying them more widely (vs.only using 1 or 2 constructs) to tailor their messages specifically towards this group to improve COVID-19 vaccine uptake (Goodyear & Armour, 2019).

Variable Engagement and Neutral Sentiment Across Instagram Posts
While demographic information surrounding post engagement is not publicly available, in general, engagement and sentiment are important metrics used to understand the acceptance of public health messages, and specifically a willingness to get vaccinated against COVID-19.Previous research has identified positive sentiment as being associated with message uptake, compliance with public health measures and the overall success of crisis communication efforts (Coombs & Holladay, 2014).Thus, neutral comments may suggest that the commenters did not have a strong willingness to be vaccinated.
While engagement rate for individual accounts varied (Table 8), the overall engagement rate for the COVID-19 vaccine communications was .40%-where a post engagement rate between 1% and 5% is considered good, and an engagement below 1% is considered low (Sehl & Tien, 2023).For young people, engagement through "follows" and "likes" serves as a form of social validation (Goodyear & Armour, 2019).The more likes a post receives, the greater the uptake of the information (Coombs & Holladay, 2014;Peter et al., 2014), and the higher the perceived social validity of the post (Goodyear & Armour, 2019).Thus, interactions across the studied Instagram accounts are good indicators of the acceptance, or lack of acceptance, from Instagram usersmost of whom are young people.

Limitations
Several limitations were identified.First, sentiment analysis software is unable to identify sarcastic remarks and may incorrectly assign a sentiment score.There is also potential for political agendas and biases to skew public sentiment and attitudes towards communication from politicians.Another limitation across social media research is the limited publiclyavailable information about user groups and those interacting with the communications including age, gender, ethnicity, or nationality.The moderate intercoder agreement for the initial coding sessions can be considered a limitation, which could be explained by the small dataset and 11 distinct codes used.Finally, manual data collection by an English-speaking research team limited the number of accounts that could be studied-including posts from French Canadians-leaving gaps in understanding about COVID-19 communication from local and provincial leaders and public health organizations.

Future Research Directions
Future research could include a focus group study with young adults to further our understanding about effective vaccine communications with this demographic.The unique nature of the COVID-19 pandemic and the current popularity of social media platforms like Instagram have created a gap in understanding about best practices for public health communications, especially for young adults.Thus, an increased understanding about optimizing public health communications on this platform is important for future public health crises.Additional social media studies utilizing artificial intelligence and machine learning models could also be used to analyze the content of larger datasets and identify themes as they relate to the 5C model or guiding principles for crisis communication (Kumar et al., 2022).

Conclusions and Research Implications
In general, COVID-19 vaccine Instagram posts from Canadian federal actors underused best practices for vaccine communications including guiding principles for crisis communication and the 5Cs model for vaccine hesitancy.As a platform used prominently by young adultsa demographic that has exhibited vaccine hesitancy-Instagram gives federal actors an opportunity to cater to the needs and concerns of this population.One communication strategy is utilizing the guiding principles for crisis communication in the Instagram post captions, which provide a framework for building and maintaining public trust.However, findings suggest that these principles were rarely used across accounts.Furthermore, young adults have unique needs and reasons towards their COVID-19 vaccine hesitancy and addressing the 5Cs of vaccine hesitancy when developing messaging can be effective.However, this approach was not widely used by the federal accounts.
Going forward, federal actors should adopt a unified approach to vaccine communications across political party lines, and comprehensively address the 5Cs and guiding principles as they relate to the needs of a young adult audience.Addressing the specific priorities of young adults on Instagram-including discussions about confidence in the safety of vaccines, and possible risks of getting severely ill from a virus-could help increase positive sentiment and vaccine uptake.These best practices should be considered during future communication campaigns to improve engagement with the Instagram posts, uptake of the public health recommendations, and ultimately the health of Canadians.

Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
All materials used to inform this research are cited in this manuscript.DOIs and other persistent identifiers are available in the reference list.
Did this study include a pre-registration plan for data collection and/or analysis?If yes, did you include a link to the pre-registration plan in the manuscript?If yes, were deviations from the preregistration plan clearly indicated in the manuscript?
No, this study did not include a pre-registration plan for data collection or analysis.
1. To what extent have Canadian federal government Instagram accounts incorporated guiding principles for crisis communication into their COVID-19 vaccine posts? 2. To what extent have Canadian federal government Instagram accounts addressed the 5Cs for vaccine hesitancy into their COVID-19 vaccine posts? 3. To what extent did the COVID-19 vaccine posts meet the needs of young adult audiences?4. What was the overall public sentiment within the comments of included Instagram posts? 5. What was the overall public engagement with included Instagram posts?

Table 1 .
Guiding Principles for Crisis Communication Definitions, Adapted From MacKay et al., 2022c.known or unknown about the current situation; includes sharing public attitudes, engagement, responses, and uptake; honest about what is known and uncertainties surrounding the crisis; Discloses information about research, development, approval, procurement, sources of funding

Table 2 .
5C Model for Vaccine Hesitancy Definitions and Examples From the Dataset, Adapted From Betsch et al. (2018).
Individuals may have a greater willingness to get vaccinated to protect others in their community, including vulnerable populations • Discuss societal impacts of getting vaccinated beyond personal health • Mention the protection of vulnerable populations Discuss vaccinations to stop the virus and get back to normal life Complacency Individuals who consider themselves to be at a low risk for vaccine-preventable diseases tend to become complacent in terms of getting vaccinated • Mention severity and/or susceptibility of a vaccinepreventable disease • May provide case counts and information about deaths Mention of individual risk to self, loved ones and friends Confidence Low confidence in the safety and efficacy of vaccine and associated policy makes individuals less likely to get vaccinated • Outline the safety and efficacy of vaccines • Provide data about vaccine research and development, rigorous testing, and approvals process Address and debunk conspiracy theories Constraints

Table 3 .
Frequency of Use of Crisis Communication Guiding Principles Across Federal Instagram Post Captions.

Table 4 .
Frequency of Use of Crisis Communication Guiding Principles Across Federal Instagram Post Images.
a Percentage calculated as a proportion of total COVID-19 vaccine posts made by each account.

Table 5 .
Frequency of Use of 5Cs of Vaccine Hesitancy Model Across Federal Instagram Post Captions.

Table 6 .
Frequency of Use of 5Cs of Vaccine Hesitancy Model Across Federal Instagram Post Images.
a Percentage calculated as a proportion of total COVID-19 vaccine posts made by each account.

Table 7 .
Frequency of Use of 5Cs of Vaccine Hesitancy Model Across Federal Instagram Post Captions.