Editor’s note: Dr. Jerome Adams, who served as US surgeon general in the first Trump administration, is a distinguished professor in pharmacy practice and public health at Purdue University.
The ongoing measles outbreak has reached three states and serves as a stark reminder of the vital role that herd immunity plays in safeguarding our communities. Originating in Gaines County, Texas, the outbreak has now resulted in 321 reported cases, with 38 hospitalizations and two deaths, including a school-age child who was unvaccinated.
The initial epicenter within a Texas Mennonite community highlights how declining vaccination rates can lead to rapid disease transmission. While some may believe that abstaining from vaccination keeps them healthier or more resistant to diseases, the reality is that their “immunity” has, until now, been borrowed from their vaccinated neighbors. This collective shield, known as herd immunity, is not automatic or enduring; it has been built over decades through high vaccination rates.
Unfortunately, this protection is now eroding due to rising vaccine skepticism.
Herd immunity works by ensuring that a high enough portion of the population is vaccinated so that highly contagious diseases like measles can’t find a vulnerable “host” to spread to. This strategy protects those who cannot receive vaccines for medical reasons — and even those who refuse them for personal beliefs. However, as vaccine skepticism grows, many who have unwittingly benefited from herd immunity in the past are now at greater risk — ironically, from themselves.
A significant driver of current skepticism has been Robert F. Kennedy Jr. and the nonprofit organization he led, Children’s Health Defense, which has spread vaccine mistrust and misinformation for years.
Ironically — or perhaps inevitably — now that Kennedy is secretary of the US Department of Health and Human Services, he faces the largest measles outbreak in Texas and the first child death from measles in over 20 years. Recently, at President Donald Trump’s first Cabinet meeting, Kennedy acknowledged the death but seemed to dismiss the outbreak as “not unusual,” drawing widespread criticism.
Now, as the outbreak spirals, he has reversed course, declaring measles a top HHS priority. In a subsequent Fox News op-ed, Kennedy wrote, “Measles outbreak is a call to action for all of us,” emphasizing how vaccinations contribute to community immunity. This marked a dramatic shift from his past rhetoric, as he is now being forced to confront the consequences of the very skepticism he helped foster.
This moment is critical for both Kennedy and the nation. As I have previously stated, his tenure will not be defined by his work on nutrition or chronic disease (no matter how commendable) but by how he responds to an inexorably increasing number of vaccine-preventable disease outbreaks.
As Kennedy himself has acknowledged, the resurgence of measles “must serve as a wake-up call.” The disease was declared eliminated in the US in 2000, thanks to decades of high vaccination rates. But since then, growing vaccine hesitancy, driven in part by disinformation campaigns, has led to declining immunization rates and renewed outbreaks. The US Centers for Disease Control and Prevention reports that in some communities, childhood vaccination rates have dropped below the 95% threshold needed to maintain herd immunity. The result? Vulnerable populations — including infants, immunocompromised individuals and those who opt out of vaccines — are now at greater risk than ever before.
The tragic death of a child should in and of itself be enough to remind us of the serious implications of measles outbreaks. Although it’s true, as Kennedy points out, that most individuals who contract measles will not die from it, we also cannot overlook the alarming reality that 1 in 10 confirmed cases during this outbreak has required hospitalization. This statistic underscores the fact that even non-fatal cases can lead to severe health complications, including pneumonia, encephalitis, pregnancy-related issues and potential lifelong health challenges.
However, what makes measles particularly dangerous is its extreme contagiousness; many experts describe it as the most contagious virus known. It spreads through airborne particles and can linger in the air for hours. In an unvaccinated community, one infected person can spread measles to up to 90% of those around them. This is why even small declines in vaccination rates can lead to major outbreaks, with hospitalizations and deaths to follow. The Texas situation is proof that when herd immunity erodes, it’s not a matter of if, but when, these outbreaks will follow.
The challenge for Kennedy is not just responding to this particular outbreak but reversing the tide of vaccine skepticism that has grown, in part, because of his own past activism. A true leader must be willing to acknowledge mistakes — even if unintended — and correct course. If he is serious about tackling measles, Kennedy must take concrete steps to promote vaccine uptake, even in areas and times when there isn’t an active outbreak. Such measures include launching aggressive public education campaigns, ensuring vaccine access, and working with state and local officials to restore trust in immunization programs. And like his predecessors, he must consistently and unequivocally state his commitment to vaccines.
Ultimately, both Kennedy and much of unvaccinated America are receiving a crash course on the topic of herd immunity. The ability of a minority to remain unvaccinated has always depended on the decisions of a vast majority to protect them. Now, as we confront more outbreaks, one lesson is clear: Community immunity is not just a personal choice, it is a collective responsibility. Kennedy’s legacy will be defined not by what he has said in the past but by what he does now. He will be remembered either as the vaccine skeptic who turned vaccine champion or as the man at the helm of HHS when America made measles great again. For the sake of our public health, and our children, we should all hope it’s the former, not the latter.