Two vaccines against herpes zoster (shingles) are licensed in the United States and recommended by the Advisory Committee on Immunization Practices (ACIP) — and they are handled very differently. Early reports suggest providers were mixing them up.
Two vaccines, two sets of rules
| Shingrix (GlaxoSmithKline) | Zostavax (Merck) | |
|---|---|---|
| Type | recombinant, adjuvanted — RZV, licensed October 2017 | live attenuated virus — ZVL, licensed 2006 |
| Comes as | two components: a vial of freeze-dried varicella zoster virus glycoprotein E antigen, and a vial of AS01B adjuvant suspension | a vial of freeze-dried vaccine and a vial of sterile water diluent |
| Storage | refrigerated, 2°C–8°C (36°F–46°F); discard any component, or the mixed vaccine, if frozen | frozen, −50°C to −15°C (−58°F to +5°F); diluent at room temperature or refrigerated; don't freeze the mixed vaccine |
| Mixing | dissolve the antigen in the adjuvant (0.5 mL dose) | dissolve the vaccine in the diluent (0.65 mL dose) |
| After mixing | use at once, or refrigerate and use within 6 hours | mix as soon as it leaves the freezer, give at once, discard after 30 minutes |
| Route | into the muscle (intramuscular) | under the skin (subcutaneous) |
| Doses | 2 — the second 2 to 6 months after the first | 1 |
| FDA-approved for | adults 50 and older | adults 50 and older |
| ACIP recommends for | immunocompetent adults 50 and older, including people who already had Zostavax — and preferred over Zostavax | immunocompetent adults 60 and older |
Zostavax may be kept refrigerated for up to 72 hours before mixing; if it isn't used within 72 hours of leaving the freezer, it should be thrown away.
What went wrong
In the first four months of monitoring Shingrix, October 20, 2017, to February 20, 2018, the Vaccine Adverse Event Reporting System (VAERS) received 155 reports about it. 13 (8%) described an administration error, some more than one.
- 9 reports: Shingrix was injected under the skin instead of into the muscle; eight of these described injection-site reactions such as pain, redness and itching.
- One of the nine also involved a patient aged 48 — too young.
- Two described patients given the information sheet for Zostavax instead, and not told to come back for the second dose.
- The other 4:
- Shingrix given instead of the intended chickenpox vaccine (Varivax), to a person of unreported age;
- Shingrix given after being wrongly frozen;
- Shingrix given to a person aged 39;
- only the adjuvant given, never mixed with the antigen.
| Where the errors happened | Reports |
|---|---|
| Pharmacies | 9 |
| Providers' offices | 2 |
| Unknown | 2 |
CDC also received 13 public inquiries about Shingrix errors or how to avoid them: injecting under the skin (5), mixing (5), the wrong interval or schedule (2) and giving previously frozen vaccine (1).
Why it matters
Passive reports and inquiries can't show why the errors happened, but early monitoring suggests providers may be confusing the procedures and storage of the older and newer vaccines. Failing to mix the two components — and giving only one — also seems to be happening, as it has with other vaccines that need mixing.
- Shingrix given correctly, into the muscle, already causes high rates of local and whole-body reactions; injecting it under the skin can make these more likely.
- Some errors could also make the vaccine less effective.
To prevent errors, providers should know each vaccine's prescribing information, storage requirements, preparation steps and ACIP recommendations.
Sources
Based on Shimabukuro TT, Miller ER, Strikas RA, Hibbs BF, Dooling K, Goud R, Cano MV, "Notes from the Field: Vaccine Administration Errors Involving Recombinant Zoster Vaccine — United States, 2017–2018," MMWR volume 67, number 20, Centers for Disease Control and Prevention; a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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