Protecting Cancer Patients in an Environment of Vaccine Hesitancy and Refusal

Vaccines offer three types of tools when it comes to cancer. Some, like the vaccines for hepatitis B and human papillomavirus (HPV), prevent cancer. [1] Others, known as therapeutic vaccines, treat cancer. [2][3] Most vaccines, however, fall into the third category of tools, routinely recommended vaccines. Less direct in their effects on cancer, these vaccines may be easier for affected patients and their oncology teams to overlook, yet they offer an insurance without which the path to recovery becomes distinctly more complex.

Routinely recommended vaccines afford antigen-specific protection to the individuals receiving them, while also contributing to a collective protection, known as community or herd immunity. [4] Both of these benefits of vaccination are important to the treatment of and recovery from cancer—and both can be weakened in their effectiveness by vaccine hesitancy or refusal.

Direct Protection: “We hadn’t thought anything worse than cancer could happen to Emily…”
“Praying for Emily” is the story of Emily Whitehead’s recovery from leukemia. [5] Emily was the first pediatric CAR T-cell therapy recipient. Early after Emily’s diagnosis, she was hospitalized with an infection in her legs that almost necessitated amputations. In reflecting on the episode, Emily’s dad, Tom, wrote: “Nearly having Emily’s legs amputated changed our perspective. We hadn’t thought anything worse than cancer could happen to Emily, but the leg infections made us realize cancer introduced many more problems than just the disease.” (p. 47)

While Emily’s experience is anecdotal, it points to the well-known understanding that infections impact rates of morbidity and mortality among cancer patients. [6] Patients are at increased risk of infection due to treatment-related factors, so-called “malignancy-driven” factors, and personal characteristics. [7] Surgical and other procedures, as well as increased use of medical devices, increase opportunities for infection. Likewise, chemotherapy and radiation therapy increase the likelihood for infection resulting from treatment, such as from immune suppression, particularly neutropenia, and physical damage, such as disrupted mucosal surfaces. In addition, some cancerous growths can result in fistulas or obstructions that compromise typically protected environments, and individual characteristics related to age, pre-existing conditions, prior antibiotic use, and nutritional status can all contribute to a patient’s increased risk for infection.

While many infections result from pathogens that are part of the patient’s own microbiome, others reflect seasonal pathogens circulating in the community. Several common culprits are vaccine-preventable, including pneumococcus, zoster, influenza, COVID-19 and hepatitis B. [7] However, as described, pathogen-specific impacts on morbidity and mortality vary based on individual factors related to the patient, type of cancer, and course of treatment. For example, the risk for invasive pneumococcal disease is 39-fold higher in individuals with hematologic malignancies compared with the general population. [8] Likewise, younger cancer survivors are more likely to experience secondary cancers, including those caused by human papillomavirus (HPV) infection. [9] And, in the first year after a diagnosis of cancer, infections are the second most common non-cancer cause of death behind cardiovascular disease, with the most common infection-related causes being pneumonia and influenza. [10]

This increased susceptibility to vaccine-preventable infections demonstrates the importance of antigen-specific protection when available. Unfortunately, at the same time individuals need to rely on immunologic memory for protection, they are often unable to do so because of the effects of the disease and treatment on their immune system, making community immunity an equally important tool for protection.

Collective protection: “I can’t be vaccinated. I depend on you to protect me. Don’t I count?”
Following the measles outbreak that started at Disneyland in California in 2014-2015, Senators Richard Pan, also a pediatrician, and Ben Allen introduced SB277 to remove philosophical exemptions from vaccines in California. During the intense legislative session, testimony was given by Rhett Krawitt, a young child being treated for acute lymphocytic leukemia. Standing on a stool to reach the microphone, Rhett said, “I have leukemia. I can’t be vaccinated. I depend on you to protect me. Don’t I count?” [11]

At the age of 7, Rhett understood all too well the importance of community immunity—his life depended on it. Community immunity refers to the limited ability of a pathogen to spread in a community that has high numbers of immune individuals and low numbers of susceptible individuals. While least direct in its protection, community immunity can at times represent the single opportunity available to protect cancer patients during their most vulnerable periods. While the group most able to affect this protection for cancer patients are the family members and caregivers closest to the patient, each additional concentric circle beyond those individuals provides additional protection. Unfortunately, as vaccine hesitancy has increased, so, too, have rates of vaccine exemptions. [12] And, more exemptions mean higher numbers of susceptibles.

Vaccine exemptions, or legal reasons for not adhering to vaccine mandates, can be one of three types: medical, religious, or philosophical. Of these, the first is based on health; the latter two are based on beliefs. Vaccine exemptions and mandates are assigned by state laws, resulting in a patchwork of vaccine coverage across the U.S. As of spring 2025, five states allow only medical exemptions (CA, CT, ME, NY, and WV). [13] Generally speaking, rates of medical exemptions are low. Conversely, belief-based exemptions occur in pockets of like-minded community members and more closely align with vaccine hesitancy. Studies have shown that those who have belief-based exemptions are at greater risk for vaccine-preventable infections and increase the risk for vaccine-preventable diseases among vaccinated community members as well. [14]

In 2019, the WHO declared vaccine hesitancy one of the top 10 threats to health. COVID-19 arguably worsened this threat, aligned with organized efforts to leverage COVID-19-related concerns against acceptance of all vaccines. [15] In 2025, the Make America Healthy Again (MAHA) movement may further erode vaccine acceptance. [16] So, what will stand between patients like Emily and Rhett and some of the most historically dangerous infections?

Protecting “Emily” and “Rhett” amidst vaccine hesitancy and refusal
Measles is often considered the “canary in the coal mine” when it comes to the return of previously controlled vaccine-preventable diseases because it is the most infectious disease of man. Ninety percent of susceptible people will be infected after exposure to the virus, and susceptible people can be infected simply by entering an enclosed airspace occupied by someone infected with measles up to two hours earlier. Said another way, exposures can occur without ever being physically in the same space with an infected individual.

As of early April 2025, the canary has sounded the alarm in the U.S. Measles cases have been identified in 21 states and New York City. Three people have died in an uncontrolled outbreak that started in Texas. Although the number of confirmed cases in early April was reported to be just over 600, estimates suggest numbers are at least three-fold higher, particularly given that the measles death rate is typically estimated to be about one in 1,000. For context, in 2024, the U.S. had fewer than 300 confirmed cases of measles. [17]

Having an awareness of the current situation regarding vaccines and the diseases they prevent and knowing that cancer patients are at increased risk for infections, what can be done to protect these patients? While many have a role to play in addressing the current environment, that of the oncology team is among the most important for cancer patients. Oncology teams are on the frontlines of treating this high-risk group of patients, have regular opportunities to converse with family members and caregivers, and enjoy an existing trust-based relationship with all involved in the patient’s care. Therefore, specific opportunities exist, including:

1. Ensuring vaccination of patients: Because a patient’s oncology care team may see them more often and because some patients may not have primary care providers [6], consistently assessing whether patients are up to date on vaccines and providing strong recommendations for vaccinations when opportunities exist is one of the best ways to ensure direct, antigen-specific protection for each patient.
2. Promoting the importance of vaccines for family members and caregivers: Because oncology teams discuss protection measures with patients, family members, and caregivers, ensuring that regular contacts of patients understand the importance of vaccination for themselves and others around the patient can decrease the chance for patient exposure, particularly during outbreaks.
3. Addressing vaccine questions or hesitancy: Because of widespread misinformation and low levels of experience with vaccine-preventable diseases, many families have questions about vaccines. Even with limited time or detailed answers to address a family’s concerns, the oncology care team enjoys a level of trust that others may not. As such, even seemingly simple acts, like delivering strong recommendations and providing accurate sources for vaccine information, can ensure that patients and families are positioned to make informed vaccine decisions.
4. Understanding local outbreaks and vaccine coverage rates: Community immunity is defined at the local level, so it is important to know how susceptible a patient’s community is to sustained transmission if a vaccine-preventable disease arrives. Infectious disease and public health colleagues can be good sources of this information, but oncology teams are best positioned to ensure that patients, families, and caregivers are aware of local outbreaks and conditions that could increase the risk for exposure.
5. Advocating for the “Rhett’s” and “Emily’s” among us: Cancer patients benefit from communities that enjoy limited spread of infectious diseases, and oncology care teams are well-positioned to describe this. The detailed understanding and ability to explain the relative risks and benefits for their patients make frontline care providers impactful messengers, particularly when speaking to legislators, media outlets, and the public at large.

As described “with a tremendous sense of sadness” in an American Society for Transplantation and Cellular Therapy position paper about measles, Pergam and colleagues [18] wrote, “despite the innumerable lives saved by vaccines, we once again find it necessary to develop strategies to protect the most vulnerable against a disease that is preventable” (p. e328).

References
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[2] Mukherjee N, Wheeler KM, Svatek RS. Bacillus Calmette-Guerin (BCG) treatment of bladder cancer: a systematic review and commentary on recent publications. Curr Opin Urol. 2019, May; 29(3): 181-188. doi:10.1097/MOU.0000000000000595.
[3] Ferrucci PF, Pala L, Conforti F, Cocorocchio E. Talimogene Laherparepvec (T-VEC): An Intralesional Cancer Immunotherapy for Advanced Melanoma. Cancers. 2021; 13, 1383. doi: 10.3390/cancers13061383.
[4] Ashby B, Best A. Herd Immunity. Current Biology. 2021 Feb 22; 31:R161-R185.
[5] Whitehead T, Whitehead K, Whitehead E, Morton D. Praying for Emily: The Faith, Science, and Miracles that Saved Our Daughter. 2020. Worthy Hachette Book Group, New York.
[6] Kamboj M, Bohlke K, Baptiste DM, Dunleavy K, Fueger A, Jones L, Kelkar AH, Law LY, LeFebver KB, Ljungman P, Miller ED, Meyer LA, Moore HN, Soares HP, Taplitz RA, WOldestsadik ES, Kohn EC. Vaccination of Adults with Cancer: ASCO Guidelines. J Clin Oncol. 2024 Mar 18; 42: 1699-1721.
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[8] Andersen MA, Niemann CU, Rostgaard K, Dalby T, Serrig R, Weinberg DM, Hjalgrim H, Harboe ZB. Differences and Temporal Changes in Risk of Invasive Pneumococcal Disease in Adults with Hematological Malignancies: Results from a Nationwide 16-Year Cohort Study. Clin Infect Dis. 2021; 72(3):463-471.
[9] Ojha RP, Tota JE, Offutt-Powell TN, Klosky JL, Minniear TD, Jackson BE, Gurney JG. Human Papillomavirus-Associated Subsequent Malignancies among Long-Term Survivors of Pediatric and Young Adult Cancers. PLoS ONE. 2013; 8(8): e70349. doi:10.1371/journal.pone.0070349.
[10] Yang P, Zheng Y, Chen J, Ma H, Yu K, Chen Y, Yang Y, Wu B. Immediate Risk of Non-cancer Deaths After a Cancer Diagnosis. BMC Cancer. 2021; 21:963-976. doi: 10.1186/s12885-021-08707-6.
[11] Offit PA. The “Medical Freedom” Movement. 2025 Mar 11. Accessed 4/5/2025: https://pauloffit.substack.com/p/the-medical-freedom-movement
[12] Seither R, Bidemi-Yusuf O, Dramann D, Calhoun K, Mugerwa-Kasujja A, Knighton CL, Kriss JL, Miller R, Peacock G. Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten — United States, 2023-24 School Year. Morbid Mortal Wkly Report. 2024, Oct. 17; 73(41):925-932.
[13] Immunize.org. Exemptions Permitted for State Childcare and School (K–12) Immunization Requirements. 2024 July 11. Accessed 5/5/2025: https://www.immunize.org/official-guidance/state-policies/vaccine-requirements/exemptions-child-school-2024/
[14] Feikin DR, Lezotte DC, Hamman RF, Salmon DA, Chen RT, Hoffman RE. Individual and Community Risks of Measles and Pertussis Associated with Personal Exemptions to Immunization. JAMA. 2000 Dec. 27; 284(24): 3145-3150.
[15] Center for Countering Digital Hate. The Anti-Vaxx Playbook. 2020 Dec. 23. Accessed 4/5/2025: https://counterhate.com/research/the-anti-vaxx-playbook/
[16] Adhikari B, Johnson T, Bartlett M, Abdelmalek M. Measles, Pharma and Mistrust: A Conversation with MAHA Moms and Dr. Paul Offit. Why Should I Trust You? podcast. 2025 Feb 20. Accessed 4/5/2025: https://podcasts.apple.com/us/podcast/measles-pharma-and-mistrust-a-conversation-with-maha/id1788335471?i=1000694301340
[17] Centers for Disease Control and Prevention. Measles Cases and Outbreaks. 2025 Apr 3. Accessed 4/5/2025: https://www.cdc.gov/measles/data-research/index.html.
[18] Pergam SA, Englund JA, Kamboj M, Gans HA, Young JAH, Hill JA, Savani B, Chemaly RF, Dadwal SS, Storek J, Duchin J, Carpenter PA. Preventing Measles in Immunosuppressed Cancer and Hematopoietic Cell Transplantation Patients: A Position Statement by the American Society for Transplantation and Cellular Therapy. Biol Blood Marrow Transplant. 2019; 25:e321-e330.

Featured image: In this photograph, captured inside a clinical setting, a health care provider places a bandage on the injection site of a patient, who just received a vaccine. Photo courtesy: © 2020 – 2025 CDC/Unsplash. Used with permission.

DOI: 10.14229/onco.2025.04.016.001

Author: Charlotte A. Moser, MS¹

¹ Co-Director of the Vaccine Education Center at Children’s Hospital of Philadelphia and the current consumer representative on the CDC’s Advisory Committee on Immunization Practices (ACIP); ORDID ID: https://orcid.org/0000-0003-1940-1536