Individual, corporate and organizational use of social media is increasing. It is estimated that by 2015, the number of individuals and corporations who have social networking accounts will reach over three billion [10]. Sixty-five percent of adult internet users in the U.S. use social networking sites [11]. Technorati currently registers over 1.2 million blogs [12]. Thirteen percent of internet users have a Twitter account [13]. A study among Fortune 500 companies reported that 60% of corporations had Twitter accounts and 56% had Facebook profiles [14]. Among Forbes 200 largest charities, use of at least one form of social media increased from 75% in 2007 to 97% in 2009 [15]. In public health, the Centers for Disease Control and Prevention is actively using social media [16]. However, there is a lack of data on social media adoption within broader public health settings, particularly state public health departments (SHDs).

Posting on social media sites averaged once per day (Table ​(Table3,3, Table ​Table4).4). Twitter re-tweets constituted 22.5% of all tweets; only 1.5% of tweets were in response to a tweet made by a follower. The SHD was the primary author of nearly all Facebook posts (89.5%). Just over a quarter (26.9%) of Facebook posts were an auto-feed, meaning that the content was originally posted on a third-party API (e.g., HootSweet). The majority (86%) of Facebook posts received no comments and 45.1% of Facebook posts had no likes (Table ​(Table33).

The majority of Twitter tweets (79.7%) were health related, 14.1% were non-health related, and for 6.2%, the information was not adequate to determine the topic area. The health-related tweets focused on general areas of staying healthy (39.7%), diseases and conditions (26.2%), environmental health (8%), injury, violence, and safety (5.4%), emergency preparedness and response (4.6%), other diverse areas (16.1%). Specifically, the most common topics were nutrition (11.4%), heart disease (7.3%), cancer (7.3%), environmental health (6.5%), tobacco use (6.5%), flu, (5.4%) and emergency preparedness and response (3.8%).

The majority of Facebook posts (88.3%) were health-related. Non-health posts had no common threads and included topics such as deaths of prominent officials, business awards, office hours, and job openings. Of the health-related posts, 77.8% were factual health-related information, 6.8% were about services offered, and 15.7% were event announcements. The most common topics were flu (9.5%), environmental health (6.0%), heart disease (5.5%), nutrition (4.5%), tobacco (4.3%), emergency preparation (4.3%), and cancer (3.6%).

Views of photos and videos were limited. The total number of photos posted on Flickr was 167 (mean = 41.75). The ratio of views to photos ranged from 1.55 to 47.65. The mean number of You Tube videos was 30. The mean number of video views was 687 (median = 144), not including an outlier CPR-related video receiving four million views. Over three-fourths of videos (78.3%) received no likes and 70.7% of videos received no comments (Table ​(Table55).

SHD's social media use varied by population density. These findings are in contrast to previous research that found no difference in individual use of social networking sites by urban or rural location [11]. The results are similar to a study that showed rural hospitals used social media less frequently than urban hospitals [20]. Additionally, on a typical day, people living in rural areas are less likely than urban residents to visit a video sharing site [21] and only 9% of Twitter users live in rural areas [22].

Audience reach with social media was limited. Relative to a state's population, the proportion of people who comprised followers, friends, and subscribers was small. An audience member's demographic characteristics, including occupation or professional affiliations, are unknown on social media applications. It is possible that the audience is the general population, or other public health professionals, including SHD employees.

Social media is more than another communication channel. As mentioned previously, there are several ways SHDs can use social media. If utilized effectively, social media has the potential to improve the way public health agencies engage, interact and communicate with its various audiences. Specifically, social media are technologies that facilitate opportunities for engaging with the audience [1] and for creating and maintaining relationships [23]. If public health agencies can use social media to engage their audiences and create relationships, something that has previously been hindered by time and distance restrictions, then they are one step closer to establishing true community-based partnerships to address public health problems.

This study showed that, SHDs are not capitalizing on social media's interactive potential. Their one-way social media communication pattern is similar to the results of an analysis of politicians and government agency Twitter posts that revealed the most common purpose was a one-way sharing of public information [24]. Very few of the audience members were viewing the videos or photos. Using comments and likes as a proxy measure for reading posts, relatively few engaged in reading. A like indicates that a person has at least read a post or watched a video, and while there was a greater proportion of likes than comments received, it is only part of the engagement process. Research shows that if a person likes a product page, they are more likely to buy the brand, recommend the brand to others and share branded content [25]. However, liking the page does not result in purchasing the product. This may be true for public health as well. Liking a page or a post may not equal following behavioral recommendations or participation in public health programs.

There may be a few reasons why SHDs have limited social media interaction. The first may be that there is a mismatch between the content that is posted and audience preferences. SHDs are posting and tweeting about health topics and not about the agency. The health topics may be a reflection of the national health observances that were occurring during February and March, including American Heart Month, National Nutrition month, National School Breakfast Week, and Colorectal Cancer Awareness Month. If the audience is primarily other health professionals, general health content may generate fewer comments. If the audience is the general public, the content may be poorly developed or the topics may be of little interest. The majority of Facebook posts were auto feeds, meaning there was little thought given to matching the content with audience preferences for information. SHDs cannot assume that because they post content on a social media application that people will respond. It is important to communicate information in a way that reflects the audience preferences, stimulates response or discussion, and is tailored to the social media application.

Public health agencies use of social media is in the early adoption stages. Because social media use is becoming so pervasive, it seems prudent for SHDs to strategically consider how to use it to their advantage. To maximize social media's potential, public health agencies should develop a plan for incorporating it within their overall communication strategy. We recommend a framework posted by Bernoff and Li as a starting point [23]. The agency must identify what audience they are trying to reach, how that audience uses social media, what goals and objectives are most appropriate, and which social media applications fit best with the identified goals and objectives.