Optimizing Vaccine Response in Immunocompromised Patients: A Pharmacist’s Guide to Drug-Vaccine Interactions

As one of the most accessible health care professionals, community pharmacists play a significant role in identifying factors that may affect vaccine safety, effectiveness, and timing. Although vaccines remain among the most effective public health interventions, certain medications can alter the immune response to vaccination, potentially reducing protection or necessitating adjustments to vaccine schedules. Among the most important drug classes pharmacists should recognize are immunosuppressants, corticosteroids, B-cell–depleting therapies, and some antiviral agents. Understanding these interactions allows pharmacists to provide confident recommendations to their patients.^1-3

Immunosuppressive Therapies: Vaccinate Before Initiating Therapy

Many immunosuppressive medications, such as conventional disease-modifying antirheumatic drugs, biologics, chemotherapy agents, and transplant-related immunosuppressants, can diminish the immune system’s ability to mount an adequate response to vaccination.^1,3 The degree of immune suppression varies depending on the medication, dose, and duration of therapy, all of which pharmacists are extensively educated on during their training.¹

In general, inactivated vaccines are considered safe in immunocompromised patients, but their effectiveness may be reduced.² Patients vaccinated during periods of significant immunosuppression may generate lower antibody titers and may not achieve the same level of protection as immunocompetent individuals.^1,2 Consequently, when feasible, vaccines should be administered before the initiation of immunosuppressive therapy.^1-3 The CDC recommends that, ideally, both live and nonlive vaccines be administered at least 2 weeks before the start of immunosuppressive treatment.¹ If vaccination occurs during intensive immunosuppressive therapy, revaccination may be considered after immune function has recovered or improved, depending on the clinical situation and the specific vaccine involved.¹ Community pharmacists are well positioned to identify patients who may benefit from vaccine assessment before beginning immunosuppressive treatment, especially with the recent increase in the use of biologics to treat conditions such as arthritis, gastrointestinal disorders, and skin disorders.^2,3

Corticosteroids: Dose and Duration Matter

Corticosteroids are among the most prescribed medications that can affect vaccine response. However, not all corticosteroid use results in clinically significant immunosuppression.¹ According to CDC guidance, high-dose systemic corticosteroid therapy is generally defined as the equivalent of at least 20 mg of prednisone daily (or 2 mg/kg/day for patients weighing less than 10 kg) for 14 days or longer.¹ Such therapy may suppress immune function sufficiently to raise concerns regarding both vaccine safety and efficacy, particularly with live vaccines.^1,3 Patients receiving high-dose systemic corticosteroids should generally defer live vaccines until at least 1 month after discontinuation of therapy, whereas inactivated vaccines can be delayed if possible or given before the initiation of therapy.¹

Importantly, lower-dose corticosteroid regimens, short-term courses lasting less than 14 days, inhaled corticosteroids, topical preparations, and intra-articular injections are generally not considered contraindications to vaccination.¹ This is a common misconception among health care providers in all settings and often leads to missed vaccination opportunities. Pharmacists should therefore carefully assess the route, dose, and duration of corticosteroid therapy before making or avoiding vaccine recommendations.

B-Cell–Depleting Therapies: A Unique Challenge

Some of the most clinically significant drug-vaccine interactions involve B-cell–depleting therapies such as rituximab (Rituxan; Genentech, Inc), ocrelizumab (Ocrevus; Genentech, Inc), and other anti-CD20 monoclonal antibodies. This is because these agents target B lymphocytes, which are essential for antibody production and long-term humoral immunity.^1,2 Because B-cell depletion can persist for months after treatment, vaccine-induced antibody responses may be substantially impaired.^4,5 Data from multiple studies have demonstrated reduced serologic responses to influenza, pneumococcal, COVID-19, and other vaccines in patients receiving anti-CD20 therapies.^4-6

The CDC recommends administering nonlive vaccines at least 2 weeks before initiating anti–B-cell therapy if possible.¹ For patients already receiving treatment, vaccination is often delayed until immune recovery occurs. Current CDC guidance suggests waiting at least 6 months after anti–B-cell therapy before administering nonlive vaccines.¹ Most patients receiving B-cell–depleting therapies should avoid live vaccines shortly before, during, and for several months after treatment due to concerns regarding safety and inadequate immune responses.²

Antiviral Medications: A Consideration for Live Vaccines

Although antivirals generally do not directly impair the immune system, certain agents can interfere with the replication of live attenuated vaccine viruses, thereby reducing vaccine effectiveness.¹ The most notable example involves antiviral medications active against influenza viruses, including oseltamivir (Tamiflu; Genentech, Inc), zanamivir (Relenza; GlaxoSmithKline), peramivir (Rapivab; BioCryst Pharmaceuticals, Inc), and baloxavir marboxil (Xofluza; Genentech USA, Inc). These medications can inhibit the replication of influenza vaccine live, intranasal (FluMist; MedImmune, LLC), a live attenuated influenza vaccine (LAIV), potentially preventing an adequate immune response.¹ CDC guidance recommends avoiding LAIV administration within 48 hours after stopping oseltamivir or zanamivir, within 5 days after peramivir, and within 17 days after baloxavir.¹ Additionally, if antiviral treatment is started shortly after LAIV administration, revaccination with an appropriate inactivated influenza vaccine may be necessary.¹ Although there are specific recommendations for LAIV timing, the efficacy of any live vaccine may be affected by antivirals.

This interaction highlights the importance of reviewing recent medication use when patients present for vaccination. Pharmacists administering influenza vaccines should routinely inquire about recent antiviral therapy to ensure optimal vaccine effectiveness.¹

The Pharmacist’s Role

Medication-related reductions in vaccine response are increasingly relevant as more patients receive biologic therapies, immunosuppressants, and specialty medications. Community pharmacists are uniquely positioned to identify these potential interactions during medication reconciliation, immunization screening, and patient counseling.^3,7

By recognizing how immunosuppressants, corticosteroids, B-cell depleting therapies, and certain antivirals affect vaccine response and timing, pharmacists can help ensure patients receive vaccines at the most appropriate time to maximize protection. Proactive communication with prescribers and patients remains essential, particularly when vaccination opportunities exist before the initiation of immune-modifying therapies.^1,7 As the immunization landscape continues to evolve and more patients look to pharmacists as the vaccine experts, pharmacists must remain vigilant and informed regarding drug-vaccine interactions to support safe and effective vaccination practices for all patients.

REFERENCES

1. Altered immunocompetence. CDC. June 26, 2024. Accessed June 22, 2026. https://www.cdc.gov/vaccines/hcp/imz-best-practices/altered-immunocompetence.html

2. Furer V, Rondaan C, Heijstek MW, et al. 2019 update of EULAR recommendations for vaccination in adult patients with autoimmune inflammatory rheumatic diseases. Ann Rheum Dis. 2020;79(1):39-52. doi:10.1136/annrheumdis-2019-215882

3. Rubin LG, Levin MJ, Ljungman P, et al; Infectious Diseases Society of America. 2013 IDSA clinical practice guideline for vaccination of the immunocompromised host. Clin Infect Dis. 2014;58(3):309-318. doi:10.1093/cid/cit816

4. Eisenberg RA, Jawad AF, Boyer J, et al. Rituximab-treated patients have a poor response to influenza vaccination. J Clin Immunol. 2013;33(2):388-396. doi:10.1007/s10875-012-9813-x

5. Hua C, Barnetche T, Combe B, Morel J. Effect of methotrexate, anti-tumor necrosis factor α, and rituximab on the immune response to influenza and pneumococcal vaccines in patients with rheumatoid arthritis: a systematic review and meta-analysis. Arthritis Care Res (Hoboken). 2014;66(7):1016-1026. doi:10.1002/acr.22246

6. van Assen S, Holvast A, Benne CA, et al. Humoral responses after influenza vaccination are severely reduced in patients with rheumatoid arthritis treated with rituximab. Arthritis Rheum. 2010;62(1):75-81. doi:10.1002/art.25033

7. Curtis JR, Johnson SR, Anthony DD, et al. American College of Rheumatology guidance for COVID-19 vaccination in patients with rheumatic and musculoskeletal diseases: version 5. Arthritis Rheumatol. 2023;75(1):E1-E16. doi:10.1002/art.42372