Shingles, also known as herpes zoster, results from a reactivation of latent varicella-zoster virus (VZV, chickenpox) and usually occurs decades after primary infection.1 Rates of chickenpox infection in the United States have been very low since the advent of VZV vaccination in 1995; however, many individuals who were infected prior to the vaccine being made available are still at risk of developing shingles.2 Ninety-nine percent of people 40 years and older have been infected with wild-type VZV in the United States and are thus at risk of developing shingles, underscoring the importance of vaccination.3,4

Although the coronavirus disease 2019 (COVID- 19) pandemic has changed how health care services are provided, ensuring immunization services are maintained is essential to public health.5 The CDC recommends that routine vaccinations not be delayed and be given according to the Advisory Committee on Immunization Practices (ACIP) immunization schedule as long as there are no contraindications.5 In this article, we discuss counseling pearls and considerations for the shingles vaccine, such as navigating insurance coverage, managing adverse events, and handling a missed dose in the series.

ACIP-RECOMMENDED SHINGLES VACCINE
Until recently, 2 vaccines were available in the United States to protect against shingles: a live, attenuated vaccine (Zostavax, Merck) and an adjuvanted, nonlive recombinant vaccine (Shingrix, GlaxoSmithKline).6-8 As of July 1, 2020, Zostavax is no longer manufactured in the United States (although any remaining supply may be used until the vaccine expires on or before November 18, 2020).6 Shingrix is now the vaccination recommended by the ACIP for immunocompetent patients aged 50 years or older (including those with chronic health conditions such as renal failure, diabetes mellitus, rheumatoid arthritis, or chronic pulmonary disease) regardless of whether they have had shingles in the past.6,9 The vaccine is administered as a 2-dose series by intramuscular injection, spaced 2 to 6 months apart.1 Vaccination administration can be delayed in patients who are experiencing an acute episode of shingles.9 Patients who are prescribed low-dose immunosuppressive therapy (that is, prednisone < 20 mg/day or its equivalent) can still receive Shingrix.9

SHINGRIX VACCINE EFFICACY
Although shingles can occur at any age, it is most common in people 50 years or older because of age-related decline in the functionality of T-cell–mediated immunity to VZV, which, when functioning appropriately, prevents viral reactivation.10 Because of the waning immune response, it is important that patients in this population receive Shingrix to prevent VZV reactivation and subsequent shingles, as well as complications such as postherpetic neuralgia (PHN), encephalitis, hearing and vision loss, and death.1,11

The Shingrix vaccine contains VZV antigen glycoprotein E that is essential for viral replication and viral spread from cell to cell; it is also a primary target of the VZV immune response.12 The antigen is combined with the ASO1B adjuvant system because this system promotes a strong CD4 T-cell and humoral immune response against recombinant proteins, leading to a stronger and sustained immune response.12 The vaccine provides over 90% protection against shingles and associated PHN, with no significant variation in efficacy based on age. (In comparison, Zostavax is only about 51.3% effective and has shown decreasing effectiveness with age—that is, the effectiveness of the vaccine decreases more rapidly over time in older patients).12,13

Patients should be informed that although Shingrix is over 90% effective, there is still a small chance they may develop shingles after receiving the vaccine.1 Vaccination should still be encouraged, however, as it will still reduce the risk and associated complications should shingles develop.

ADVERSE EVENTS WITH SHINGRIX
Overall, the majority of adverse events (AEs) with the Shingrix vaccine are mild to moderate in severity. About 1 in 6 people will experience a severe AE that prohibits them from participating in normal daily activities.14 The most commonly reported AEs were a sore arm and redness and swelling at the injection site.14 Other AEs include fatigue, muscle pain, headache, shivering, fever, stomach pain, and nausea.15 Although no specific studies have evaluated analgesic coadministration with Shingrix, we would extrapolate from other vaccinations; ibuprofen or acetaminophen can be recommended to reduce pain and discomfort.14 In clinical trials, the median duration of AEs was 2 to 3 days, and patients should be counseled on this time line.15 Patients also should be counseled on the importance of the second dose for enhanced immunogenicity regardless if they experience an AE. If a patient has a reaction to the first dose, it does not necessarily mean they will have a reaction to the second dose.14

IF A PATIENT MISSES A DOSE
If a patient misses the second dose of Shingrix (that is, if more than 6 months has passed since the first dose), the vaccine series does not need to be restarted; however, the second dose should be administered as soon as possible.9 Patients should be advised that Zostavax and Shingrix are not interchangeable. If a patient was started on the series with 1 vaccine, they should continue with that same vaccine. However, given that Zostavax is no longer being manufactured in the United States, patients who received Zostavax in the past should receive Shingrix for their subsequent doses.9

SHINGLES VACCINE AND REDUCED STROKE RISK
Evidence suggests an increased risk of acute ischemic stroke following shingles. The risk seems to be highest within the first year following a shingles episode.16 A possible explanation for the increased risk is that shingles causes inflammation and subsequent remodeling of the vasculature, leading to stroke.16 Zostavax may reduce the incidence of stroke, according to results from a study presented at the International Stroke Conference 2020 in Los Angeles, California.17 The study involved Medicare fee-for-service beneficiaries 66 years or older who had received Zostavax between 2008 and 2014 and had not experienced a stroke (n = 1,382,051) and individuals who had not received the vaccine, matched on the basis of a comprehensive list of variables (n = 1,382,051). With a median follow-up of 3.9 years, those who received Zostavax experienced lower stroke incident rates per 1000 person-years than those who had not received the vaccine (all stroke events, 7.8 vs 8.45; acute ischemic stroke, 5.40 vs 6.53; hemorrhagic stroke, 0.73 vs 0.82; P <.001). Although the reduced incidence of stroke associated with Zostavax appeared to be greater among those aged 66 to 79 years than those 80 years or older, the incidence rate remained consistent across sex and race.17 Of note, Zostavax was studied because it was the only vaccine available during this time period.

SHINGLES VACCINE AND COVID-19
The COVID-19 pandemic has led to a dramatic decrease in routine primary care visits and vaccine rates among all age groups due to stay-at-home orders.5 Adult immunization is imperative to reducing hospitalizations caused by vaccinepreventable diseases, especially when the health care system is already burdened by the pandemic.5 With COVID-19 more severely affecting older populations who are also more at risk for herpes zoster, the vaccine can help prevent shingles and shingles-related complications that could result in hospitalization.1,18 Patients should be screened for shingles vaccination based on age and counseled on the importance of returning within 6 months for their second dose.

INSURANCE COVERAGE AND SHINGRIX VACCINE AVAILABILITY
The Shingrix vaccine is covered by most health insurance providers, including Medicare Part D and Medicare Advantage Plan Part C.19 GlaxoSmithKline, the manufacturer of Shingrix, also offers an assistance program for patients who do not have third-party coverage or who have spent at least $600 in prescription drug costs through their Medicare Part D Prescription Drug Plan and meet criteria for assistance.20

Health care providers should always be aware of back orders prior to offering the vaccine to their patients. Prior manufacturer back orders of Shingrix have led to delays in vaccination for some patients; however, this has since been resolved.21  
 
ALEXANDRA HANRETTY, PHARMD, is a clinical pharmacy specialist in infectious diseases at Cooper University Health Care in Camden, New Jersey.

LUCIA ROSE, PHARMD, is a clinical pharmacy specialist in infectious diseases at Cooper University Health Care in Camden, New Jersey.



REFERENCES
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