As the United States faces its largest measles outbreak in three decades, one of the nation’s most storied public health voices has largely fallen silent on social media.
A new exploratory analysis suggests that the Centers for Disease Control and Prevention (CDC) dramatically scaled back its social media posts during the first seven months of 2025, creating what researchers call a “health communication void.” That empty space was quickly filled by news media and, in some cases, less-credible voices.
The study, published in Vaccine, examined measles and measles, mumps, and rubella (MMR) vaccine-related posts from official CDC accounts on Facebook, Instagram, and X, alongside posts from major news outlets. From January 1 to August 1, 2025, the CDC posted just 10 times about measles across the three platforms. In contrast, the agency averaged nearly 46 measles-related posts during the same period in each of the previous four years, despite far fewer measles cases during that timeframe.
Steep drop in communication amid unprecedented outbreak
The drop-off was especially striking given the scale of the outbreak. By October 2025, more than 1,600 measles cases had been reported across 42 states, making it the highest annual case count since 2000, when measles was declared eliminated in the United States. By August 8, US cases had reached 1,356 cases, according to data from the Pan American Health Organization.
What’s more, none of the CDC’s 2025 social media posts supported MMR vaccination, the most effective way to prevent measles infection. (In the 2021 and 2024 timeframe, 82% of posts encouraged immunization or catch-up vaccination.) When the words “vaccine” or “immunization” were included in the CDC’s 2025 posts, it was to describe response efforts to the outbreak and not to encourage vaccination.
Most of the CDC’s 2025 measles posts were clustered in a brief window in late February and early March, following the measles-related death of a child in West Texas. The posts were largely reactive and text-heavy, often amplifying statements from US Health and Human Services Secretary Robert F. Kennedy Jr., rather than directing audiences to CDC vaccine resources.
Historically, most CDC measles posts linked to authoritative guidance on the agency’s website; in 2025, only half did.
News media, other voices left to fill the void
As the CDC’s voice diminished during the 2025 outbreak, news media stepped in. The researchers identified more than 1,000 measles-related social media posts from 25 major news outlets over the same period. Coverage spiked around key moments during the outbreak, including the first reported death, case surges in West Texas, and the declaration of the largest outbreak in 30 years.
But news coverage, the authors caution, is not the same as public health communication. News organizations operate in an attention economy, in which urgency and conflict (more than straightforward, science-supported information) draw in readers. Health agencies must also compete for readers, but that goal is second to encouraging the public to engage in specific health behaviors like vaccination.
Professional medical organizations, including the American Academy of Pediatrics (AAP), the American Medical Association (AMA), and the American Academy of Family Physicians (AAFP), increased their social media activity later in the outbreak, but their combined audience remained a fraction of the CDC’s audience. Across Facebook, Instagram, and X, the AAP, AMA, and AAFP have approximately 2.5 million followers, compared with the CDC’s 12 million followers.
The CDC’s silence also created room for anti-science organizations to fill the void. Children’s Health Defense (CHD), an organization that had been deplatformed from Facebook and Instagram for spreading mis- and disinformation, posted 101 times on X during the outbreak. Its posts focused largely on the alleged dangers of the MMR vaccine while simultaneously downplaying the seriousness of the outbreak. CHD’s social media presence isn’t insignificant; it has approximately three times as many followers on X as the AAP does.
The study’s authors argue that silence from trusted public health institutions carries real risks. In polarized environments like social media, information gaps are rarely left empty, and political and science-skeptical voices have room to attain agenda-setting power. If mainstream media are allowed to set the agenda, measles becomes just another headline rather than a preventable disease that demands public attention and action.
To help prevent this, the authors encourage the CDC to continue posting evidence-based health campaigns, especially those that promote proactive health measures, such as immunization.
