A county health department’s transition to intradermal administration
- A community health department quickly adapted Centers for Disease Control and Prevention guidance during the Mpox outbreak by switching to intradermal vaccine administration and training nurses efficiently.
- Collaboration among public health programs streamlined processes, improved safety, and expanded vaccine access, ultimately strengthening public health outcomes.
ON JUNE 27, 2022, the Lake County Health Department (LCHD) announced the first probable case of mpox virus (clade II) in Lake County, Illinois. On August 1, 2022, the state of Illinois issued a Gubernatorial Disaster Proclamation after Illinois reported the third highest number of mpox cases in the United States—520 as of the Proclamation date.
In anticipation of rising case numbers, LCHD planned a weekly community vaccine clinic to provide the smallpox/mpox (JYNNEOS) vaccine to individuals at risk of exposure, including, but not limited to, gay, bisexual, and other men who have sex with men (MSM) with multiple recent sexual partners; those whose sexual partners meet those criteria; and those with a known or suspected exposure to mpox as defined by the Advisory Committee on Immunization Practices (ACIP).
Vaccine shortage and response
Vaccination plays an important preventive role in curbing the spread of mpox. However, as described by U.S. Senator Patty Murray, 2022 vaccine supplies were limited due to the finite central stockpile quantities, challenges in initial mass procurement, and distribution delays.
The traditional route for administration of the JYNNEOS vaccine is subcutaneous (0.5 mL suspension; 0.5 x108 to 3.95 x108 infectious units Modified Vaccinia Ankara – Bavarian Nordic virus/0.5 mL suspension). However, on August 9, 2022, in response to the vaccine shortage, the Food and Drug Administration (FDA) authorized the use of an intradermal route of vaccine administration (0.1 mL suspension; one-fifth of the subcutaneous dose) under an Emergency Use Authorization (EUA).
Although the adjusted vaccine effectiveness for intradermal (ID) administration is about 10% lower than subcutaneous (SQ) (80.3% for ID vs 88.9% for SQ), the confidence intervals and effectiveness estimates overlapped. Based on this, Dalton and colleagues concluded that the intradermal route provided a similar level of protection in the context of the outbreak. According to Frey and colleagues and the Centers for Disease Control (CDC), intradermal administration allows for more vaccinations per vial without compromising the effectiveness of the vaccine.
Nurses’ role in clinic implementation
After the initial reports of mpox cases in the United States and weeks before FDA authorization, LCHD planning efforts for a community clinic began with vaccination outreach targeting individuals at risk of acquiring the infection. The public health physician wrote standing orders, under the Illinois General Assembly Public Health Standing Order Act, for administering vaccines in the clinic. Preemptive preparation for vaccine administration as a public health intervention allowed for immediate action upon receipt of FDA authorization.
LCHD implemented intradermal vaccine administration on August 11, just 2 days after FDA authorization. Key skills of nurses and programmatic staff within the LCHD communicable disease, immunization, sexually transmitted infections (STI), and tuberculosis programs aided the rapid and successful transition to intradermal administration.
Because of their extensive experience in planning and organizing COVID-19 mass vaccination clinics, the immunization nurse coordinator led those efforts for an mpox clinic. This involved creating job aids, patient screening forms, medical record documentation, a process for addressing medical concerns before and after vaccination, and developing and coordinating vaccinator training. The immunization team entered documentation into LCHD’s electronic health record, which transmitted to the state registry.
The tuberculosis nurse team, with their experience administering intradermal tuberculin skin tests, helped develop vaccinator training for public health nurses, based on CDC and Immunization Action Coalition guidance. Public health flex nurses and vaccinators from the Medical Reserve Corps assisted with vaccination efforts and began training. In addition, the Emergency Response Team provided plans for obtaining daily supplies, selecting and setting up the vaccination site, determining clinic capacity, and offering just-in-time training for support clinic staff (greeters, traffic, and medical observers), such as directing traffic to the clinic site and guiding the flow of patients within the clinic, providing educational materials, assisting with paperwork, and monitoring patients for adverse reactions.
The nonclinical STI team (consisting of case managers and health educators) leveraged their strong working relationships with vulnerable populations and previously established social media networks for outreach and information sharing about the vaccination clinics. The tuberculosis and STI public health clinics urgently scheduled anyone identified as a close contact to someone with confirmed mpox. Public health nurses vaccinated these patients under the public health physician’s standing orders. In addition, STI clinic staff contacted all patients who met ACIP criteria for a risk of mpox exposure to inform them of vaccine availability.
The specialized skills of public health nurses—such as culturally sensitive interviewing, health education tailored to varying literacy levels, patient communication, resource navigation, and planning and implementation of public health interventions—aided in optimizing limited vaccine supplies and ensuring successful intradermal administration. When patients vaccinated with the first dose expressed concerns about scarring from intradermal administration, STI staff shared this feedback with the nurses assisting in the clinic. This led to offering alternative vaccination injection sites, such as the back. (See Scarring: A serious concern.)
Scarring: A serious concern
Although vaccine adverse reactions reported to the Lake County Health Department (LCHD) were minor (for example, localized erythema), sexually transmitted infection staff noted that some patients experienced scarring from intradermal vaccinations, which appeared more prominently in patients with darker skin tones. In this patient population, already subject to social stigma, the presence of a scar may identify an individual’s vaccination status, potentially leading to unintentional disclosure and exposing them to judgment, discrimination, or breaches of privacy within their social networks.
Visible scars can lead a person to feel self-conscious, uncomfortable, and dissatisfied with their appearance, which may perpetuate low self-esteem. Additionally, the potential for long-lasting or visible marks may deter some from seeking vaccination, particularly if they perceive the cosmetic consequences to outweigh the benefits of protection. These concerns have broad public health implications, as perceptions of the intradermal route as disfiguring or stigmatizing may reduce vaccine acceptability and undermine confidence, particularly in vaccine-hesitant or historically underserved communities.
LCHD public health nurses navigated these concerns. Their role extended beyond vaccine administration to include patient education, reassurance, and advocacy. Nurses provided clear, empathetic communication about what to expect after intradermal vaccination, acknowledged concerns about scarring without minimizing them, and offered strategies for scar care when appropriate.
Frey and colleagues found that more than one-third of individuals experience injection site discoloration that remains 6 months after receiving an intradermal injection. With an adequate vaccine supply, the Centers for Disease Control and Prevention now recommends the preferential use of the standard subcutaneous regimen, with intradermal listed as the alternative. This update alleviates the scarring concerns.
During the clinics, tuberculosis nurses oversaw just-in-time training, answered staff questions, supervised vaccinators, and helped troubleshoot administration errors as they arose. When demand for the vaccine decreased and supplies increased, the long-term sustainable plan included STI nurses continuing to provide mpox vaccinations to vulnerable patients seen in their clinic or referring them to a preferred pharmacy.
Maximizing vaccine doses
An issue identified during the first clinic involved difficulty drawing five full doses from each vial. Although each vial contained sufficient vaccine for either one 0.5 mL subcutaneous dose or five 0.1 mL intradermal doses, some vaccinators initially struggled to obtain five complete intradermal doses per vial because of the drawing technique and syringe.
An immunization coordinator with experience drawing vaccines for the COVID-19 clinics helped troubleshoot the issue and found that using low-pressure syringes allowed for successfully drawing five doses. This discovery optimized the doses of the limited supply. On August 22, 2022, LCHD shared this information with the state health department, which supported LCHD’s presentation of findings on a call with other state and local jurisdictions planning community vaccine clinics.
Between August 11 and September 1, 2022, with the assistance of skilled public health nurses, 298 patients received the vaccine across four LCHD clinics. All nurses showed progressive improvement in intradermal administration accuracy and dose drawing efficiency. At the first clinic, nurses administered 101 doses—49.5% (n=50) intradermal, 43.6% (n=44) subcutaneous, and 6.9% (n=7) intradermal administration errors. If two attempts at intradermal administration proved unsuccessful, nurses gave a complete subcutaneous dose in the arm. Initially, nurses drew four doses from each vial. In total, 66 vials were consumed, or approximately 1.5 doses per vial.
By the second clinic, outcomes had improved: 59 doses were administered—91.5% (n=54) intradermal, 3.4% (n=2) subcutaneous, and 5.1% (n=3) intradermal administration errors. Efficiency rose, with eight vials yielding five doses each, leading to an average of 3.7 doses per vial and a total of 16 vials used. In the third and fourth clinics, nurses administered nearly all doses intradermally (100% and 94.8%, respectively) with over 4.6 doses drawn per vial. From the first to the fourth clinic, the proportion of intradermal doses increased by 91.5%, and dose drawing efficiency improved by 220%, demonstrating substantial improvement in both accuracy and resource utilization. (See Intradermal administration improvement.)
Intradermal administration improvement
The Lake County Health Department community clinics demonstrated improvement in efficiency and accuracy of intradermal (ID) administration of the JYNNEOS vaccine from the first clinic (August 11, 2022) to the final clinic (September 1, 2022).
administered
* Vaccine Adverse Event Reporting System (VAERS) reports completed in the August 11 clinic were for incorrect administration of ID injections (absence of wheal) in two attempts, requiring subcutaneous (SQ) administration of the vaccine. VAERS reports for the August 18 and September 1 clinics were for administration errors with the first ID dose.
Future research
Although Lake County has had a substantial decrease in mpox cases since 2022, with a significant drop from 10 cases in 2022 to only five from 2023 to 2025, this can’t be attributed to the impact of vaccines alone. Vaccines served as one of several preventive tools aimed at slowing the outbreak. According to a study by Clay and colleagues, behavior modifications may have led the charge in slowing the national outbreak initially, while the use of vaccinations may have helped reduce its duration.
Further investigation of intradermal vaccine administration may serve as a key emergency preparedness strategy when communities face limited vaccine supply. A meta-analysis by Schnyder and colleagues demonstrated that intradermal influenza and rabies vaccines offer protection comparable to conventional administration routes. However, research remains limited on the efficacy of dose-sparing intradermal administration of other vaccines, such as those against Ebola and Japanese encephalitis. A meta-analysis of safety and immunogenicity data across a diverse population may allow for a better understanding of the role of intradermal vaccinations in combatting mpox and add to support of the overall use of this administration route in emergency responses.
Challenges and solutions
The implementation of the mpox vaccination clinic and transition to intradermal administration presented several challenges, each offering valuable lessons that will inform future interventions. For example, onsite practical training of vaccinators in the intradermal method initially proved challenging for nurses, many of whom had little or no experience with the technique, particularly in inserting the needle at the correct angle and depth to create a proper wheal. Tuberculosis nurses remained on-site as a resource to share their expertise and troubleshoot concerns as they arose.
Ensuring patient privacy in the clinic proved challenging. Patients sat together in a shared check-in and waiting area, and privacy screens weren’t used during vaccination unless clothing removal was necessary. Given the sensitivity surrounding vaccine administration and the stigma associated with the mpox vaccine, plans for future clinics should prioritize the addition of privacy measures to protect patient confidentiality.
Language barriers also posed a challenge. Several patients spoke primarily Spanish, but the clinic had only one Spanish-speaking staff member. In response, community clinics now include additional Spanish-speaking staff to aid patient communication.
The clinic experienced difficulty tracking vaccine administration and waste when a second dose was needed after an unsuccessful first intradermal attempt. To streamline operations and enhance oversight, in the future, the clinic can establish a process for promptly reporting and documenting a repeated dose. For example, clinics can designate a staff member to report administration errors in a standardized incident log and to the Vaccine Adverse Event Reporting System.
The transition from subcutaneous to intradermal vaccine administration significantly slowed the vaccination process, as nurses unfamiliar with the technique required more time per patient. Staffing additional nurses may help maintain efficiency and minimize patient wait times when transitioning from subcutaneous to intradermal administration.
A nurse-led model
As one of the first community vaccination providers to administer JYNNEOS intradermally, LCHD had the opportunity to provide vaccines to patients from neighboring areas without access to the vaccine, extending its impact beyond county lines. LCHD staff shared their insights on national and state calls with the Illinois Department of Health, providing critical information for local, state, and national vaccination strategies.
Although the number of clade II mpox cases reported in the United States has declined substantially—from a peak of over 11,000 cases per month in 2022 to 200 or fewer cases per month from 2024 to date—the risk of mpox transmission hasn’t been eliminated. With an ongoing outbreak of a deadlier strain of mpox (clade I) in Central and East Africa, spread to Western parts of Europe, and a report of the first case in California in November 2024, vaccination efforts for those at highest risk have become even more important. In recent months, the United States has reported an increasing number of clade I mpox cases, with more than 20 cases identified as of June 1, 2026. LCHD’s mpox clinics provide a nurse-led model that others can apply in prevention and response efforts for emerging diseases.
Amy Zun is a medical student at the University of Chicago Pritzker School of Medicine in Chicago, Illinois. Yves Helou is a crisis epidemiologist at Lake County Health Department (LCHD) and Community Health Center in Waukegan, Illinois. Denise Flores is a communicable disease and immunization coordinator at LCHD and Community Health Center. Dhiya Bakr is a retired tuberculosis program coordinator at LCHD and Community Health Center. Valerie Johansen is a program coordinator at LCHD and Community Health Center. Patricia Corn is an emergency response coordinator at LCHD and Community Health Center. Emily Young is a communications manager at LCHD and Community Health Center. Sara Zamor is an associate director of prevention at LCHD and Community Health Center. Lisa Kritz is director of prevention at LCHD and Community Health Center. Connie Austin is a state public health veterinarian at the Illinois Department of Public Health in Springfield. Sana Ahmed is a medical epidemiologist at LCHD and Community Health Center.
American Nurse Journal. 2026; 21(8). Doi: 10.51256/ANJ082614
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Key words: Mpox, vaccines, public health
