Carol McLay, DrPH, MPH, RN, CIC, FAPIC, FSHEA, 2025 APIC President

(Photo credit: APIC)

In the face of a growing measles outbreak and renewed public skepticism fueled by conflicting government messages, Infection Control Today^® (ICT®) sat down with Carol McLay, DrPH, MPH, RN, CIC, FAPIC, FSHEA, 2025 president of the Association for Professionals in Infection Control and Epidemiology (APIC), discusses the evidence behind measles vaccine safety, the dangers of misinformation, and the vital role infection preventionists (IPs) play in protecting public health and rebuilding trust in vaccination programs.

ICT: What evidence supports the safety and efficacy of the measles vaccine, and how thoroughly has it been tested?

Carol McLay, DrPH, MPH, RN, CIC, FAPIC, FSHEA: The measles vaccine, usually given as part of the MMR vaccine (measles, mumps, rubella), is one of the most effective and well-studied vaccines we have. Two doses offer about 97% protection against measles, and a single dose provides around 93%. In fact, widespread vaccination helped eliminate measles transmission in the US by the year 2000. Globally, the World Health Organization (WHO) estimates that measles vaccination efforts have prevented over 60 million deaths between 2000 and 2023. That’s an astonishing number and a powerful reminder of what infection prevention efforts can achieve.

When it comes to safety, the record is just as strong. The vaccine has been safely given to hundreds of millions of people around the world. Decades of careful monitoring and peer-reviewed studies show it is overwhelmingly safe. Most side effects are mild, such as a sore arm, a low-grade fever, or a rash. In rare cases, young children might have a febrile-related seizure, but these are temporary and do not cause long-term harm.

What about autism? It’s understandable that people still have concerns, but the science is very clear: There is no link between the MMR vaccine and autism. The 1998 study that raised that fear has been thoroughly discredited and retracted, and countless studies since then that have included millions of children have found no association.

The evidence is solid, but it’s also okay to have questions. For those of us in infection prevention, our role isn’t just to share the data; it is to listen, respond with respect, and help people feel confident and cared for when making decisions about their health.

ICT: Can you speak to vaccine misinformation’s impact on measles outbreaks and public health more broadly?

CM: It is easy to say that false information has fueled measles outbreaks. There is truth to that. But the deeper issue is trust. Many of the people who now question vaccines are not simply misinformed. They are reacting to real experiences, disappointments, and fears related to the health care system; those emotions matter.

Over the past few decades, vaccination rates have declined in certain communities where trust in public health and health care has eroded. When measles vaccination coverage drops below the level needed for community protection, around 95%, we start to see outbreaks. That is exactly what is happening in the US today. People who are unvaccinated are not always making decisions based on a lack of intelligence or care for others. In many cases, they have had experiences that left them feeling unheard, dismissed, or judged. And once trust is broken, simply providing more facts is not enough to rebuild it.

The result is that diseases like measles, which was once eliminated in the US, are coming back. These outbreaks put lives at risk, especially among infants, immunocompromised individuals, and others who cannot be vaccinated. But pointing fingers or labeling people does not change minds. What will help is building relationships, listening, and creating space for honest questions and concerns.

As IPs, we are in a unique position. We can be trusted voices within our organizations and communities. Instead of focusing only on correcting beliefs, we can engage in conversations that start with empathy and respect. If we truly want to rebuild confidence in vaccines, we must show that we care about people and listen to their stories, values, and fears.

ICT: What are the short- and long-term consequences of undermining public trust in vaccination programs? How concerned are you by public statements from government officials that question the safety of vaccines, particularly the measles vaccine?

CM: Eroding public trust in vaccination programs has immediate and long-lasting consequences. In the short term, lowered vaccination rates can lead to outbreaks of vaccine-preventable diseases, increased hospitalizations, and unnecessary deaths. Measles, in particular, is extremely contagious and can spread rapidly in communities with even small declines in coverage. For example, measles requires approximately 95% vaccine coverage to prevent sustained transmission.
Long-term effects include the reestablishment of endemic transmission for diseases once eliminated or controlled. There is also a risk of weakening public health infrastructure, as mistrust in vaccination often extends to other public health recommendations. When public figures or government officials question the safety or necessity of vaccines without evidence, it exacerbates these problems. Recent statements by public officials casting doubt on the safety of the measles vaccine, despite its proven track record, are particularly concerning. Such remarks not only misinform the public but also give undue credibility to fringe views, making it harder for health professionals to promote evidence-based guidance. This is deeply concerning.

ICT: How would you assess the CDC’s handling of the current measles outbreak? Has it truly been “brought under control?

CM: While the CDC’s technical response to the measles outbreak has been strong, mobilizing field teams, issuing clinical guidance, and supporting vaccination efforts, its ability to lead has been undermined by political interference and limited capacity. Mixed messaging from Health and Human Services (HHS) leadership has weakened the CDC’s public health voice at a time when clarity is essential. Most alarming is the directive for the CDC to revisit the thoroughly discredited claim that vaccines are linked to autism. This is a dangerous waste of time and resources that diverts attention from urgent public health threats and lends credibility to a long-debunked myth. These actions threaten to confuse the public, erode vaccine confidence, and compromise the CDC’s ability to lead with evidence when it matters most.

The measles outbreak in North America remains active and continues to grow. Case numbers are rising steadily, and without significant improvements in vaccination coverage, the virus is expected to spread further into additional US communities with low immunization rates. Current projections suggest that transmission could continue for up to a year if these gaps are not addressed.

This outbreak is not contained within national borders. The WHO has confirmed that measles cases in Mexico are directly linked to the outbreak in Texas, highlighting ongoing cross-border transmission. Genetic sequencing indicates that the strain circulating in Texas and Mexico is the same as the one driving a large outbreak in Ontario, Canada, which has now surpassed 600 cases. This suggests that a single measles strain is actively circulating across North America, raising serious concerns about regional spread.

Despite this, Secretary Robert F. Kennedy, Jr has publicly claimed on several occasions that the outbreak is slowing, stating that the case growth in Texas has “flattened” or “plateaued.” However, these statements are not supported by epidemiologic data or by assessments from public health authorities. Reports from state health departments and the CDC show that case numbers continue to rise steadily, with no clear evidence of a sustained decline.

This disconnect between political messaging and the actual trajectory of the outbreak underscores the need for clear, evidence-based communication. Public confidence in outbreak response relies on transparency, consistency, and alignment between leadership and public health data.

ICT: What role do IPs play in managing outbreaks like measles in health care settings and communities?

CM: IPs are essential to managing measles outbreaks in health care settings and the community. Within hospitals and clinics, IPs are responsible for identifying suspected measles cases, initiating airborne precautions, and coordinating the isolation of infected patients to prevent transmission. They also verify health care worker immunity, arrange postexposure prophylaxis when needed, and monitor exposed individuals for signs of infection.

Beyond the clinical environment, IPs collaborate with public health departments on contact tracing, community education, and vaccination initiatives. They play a central role in outbreak response planning and communication, often serving as trusted messengers who can explain risks and recommendations clearly to diverse audiences. Their work not only helps contain outbreaks but also builds long-term resilience through education and policy advocacy.

ICT: How can health care professionals and organizations like APIC rebuild and maintain public trust in science-based vaccination guidance?

CM: Rebuilding public trust in vaccines requires more than accurate information; it demands consistent, compassionate communication and a commitment to meeting people where they are. Health care professionals, especially IPs, are uniquely positioned to lead this effort. They are often the most trusted messengers in their organizations and communities, and their relationships with patients and staff provide opportunities to foster confidence in science-backed guidance through respectful, honest conversations.

Organizations like the APIC play a vital role in this work. APIC provides the training, tools, and national platform IPs must lead with credibility and clarity. Through evidence-based education, policy advocacy, certification programs, and thought leadership, APIC equips professionals with the resources to speak confidently and consistently about vaccine safety and effectiveness.

APIC also helps bridge the gap between public health institutions and the public by supporting partnerships with community leaders, tailoring messaging for different populations, and amplifying the voices of frontline professionals trusted within their local contexts.

Trust is not rebuilt with a single message or campaign; it is earned over time through transparency, humility, and a visible commitment to protecting people’s health. APIC and its members are leading that work every day, not only by responding to outbreaks but also by promoting a culture of prevention, accountability, and care.