In fall 2025, several pharmacies reported that they were unable to provide COVID-19 vaccines without a physician prescription due to policy barriers linked to recent actions by the Food and Drug Administration and the Centers for Disease Control and Prevention. Pharmacies have long played a central role in COVID-19 vaccine access: at the start of the pandemic, pharmacies administered over 90% of these vaccines. Thus, maintaining these new barriers would have severely limit access. 

While measures have been taken to resolve pharmacy access issues, broader vaccine availability via providers at non-pharmacy sites of care remains a critical consideration. This issue is particularly relevant for vaccines only covered under Medicare Part D, such as herpes zoster. 

Background 

Within the United States, Medicare vaccine coverage is divided between Part B and Part D, resulting in two distinct benefit structures. Medicare Part B, administered as a medical benefit, covers vaccines such as influenza, pneumococcal, hepatitis B, and COVID-19, which can be billed by medical providers via standard medical claim processes, as well as pharmacy providers via roster and centralized billing. In contrast, Medicare Part D, administered as a pharmacy benefit, covers all other adult vaccines recommended by the Advisory Committee on Immunization Practices, including those to prevent shingles and respiratory syncytial infections, with claims processed exclusively through pharmacy billing systems (i.e., point of sale). 

This division in Medicare coverage of vaccines reflects historical program design: prior to the implementation of Part D in 2006, coverage for vaccines under Part B was directly determined by Congress’. Part D covered all commercially available vaccines that were not previously covered by Part B. From 2006 to 2020, Congress did not modify vaccine coverage, retaining the bifurcated coverage, resulting in novel vaccines (e.g., herpes zoster) being added and covered via Part D, but not Part B. In 2020, Congress again modified the Part B vaccine benefit, adding COVID-19 vaccines. 

For providers, this dual structure can create administrative complexity, particularly for Part D covered vaccines, as physician offices may need to use separate billing workflows, contract with specialized billing vendors, or refer patients to pharmacies, which may impact care coordination, patient access, and ultimately vaccine uptake.  

Analysis 

To characterize the extent to which these barriers have inhibited non-pharmacy providers from billing for Part D covered vaccines, Avalere Health reviewed Medicare Part D Prescription Drug Event (PDE) data for herpes zoster vaccinations in 2020–2022. Specifically, Avalere Health reviewed pharmacy service type codes, which indicate the type of pharmacy that dispensed the prescription, as recorded on the PDE.  Avalere Health evaluated the proportion of claims not dispensed through community/retail channels to measure drug volume through non-pharmacy provider types (e.g., medical offices). Specifically, Avalere Health reviewed the number of claims with pharmacy type code “other” (99) which is assumed to be inclusive of medical office claims.  

Findings 

At a national level, fewer than 5% of paid herpes zoster vaccination claims in Medicare Part D were from other-pharmacy provider types (Table 1). 

Table 1.  Percentage of Paid Herpes Zoster Vaccine Claims from Other Providers (i.e., Pharmacy Type Code: Other [99]), by Year 

These findings align with previously published research, including a report from the Medicare Payment Advisory Commission which found that in 2019 “the vast majority of vaccines covered under Part D are administered in retail or community pharmacies. In 2019, more than 95% of vaccines were furnished in those settings.” 

Conclusion
Medicare beneficiaries primarily access herpes zoster vaccine in pharmacy settings. For the time period assessed, there were a limited proportion of claims billed with the “other” pharmacy type code, meaning few medical providers administered herpes zoster vaccine in the medical office setting. A key explanation for this conclusion is that herpes zoster is only covered under Part D, and medical offices have difficulty billing the pharmacy benefit.  

Methodology 

Avalere Health used 100% Medicare PDE data accessed Medicare fee-for-service beneficiaries from 2018 to 2022 to analyze herpes zoster vaccine administration under Part D; data from 2020–2022 are reported above. For each year, Avalere Health compared the number of claims paid to other pharmacy using the pharmacy service type code variable (value=99), to the total annual paid claims across all pharmacy service type codes (e.g., retail/ community, compounding, home infusion, institutional, long-term care, mail order, managed care organization, specialty).