Be alert with varicella vaccines

Varicella vaccine practice alert website image

PDL has recently received several incident reports where the incorrect varicella vaccine has been prescribed and/or supplied. Prescribing software programs have variations on how the vaccines are described, potentially leading to confusion for prescribers and pharmacists.

Most reports indicate the intended varicella vaccine is for the prevention of chickenpox however transcription and selection errors have seen herpes zoster (shingles) vaccines provided. PDL is concerned about these errors, especially since PDL’s statistics show incidents involving children are more likely to lead to a regulatory complaint.

Prescriptions intended for a chickenpox vaccine have been generated with the following wordings: ‘Varicella-Zoster Virus Live Attenuated Antigen (OKA Strain) Vaccine Powder’ or ‘Varicella Vaccine Vial’.

PDL encourages all pharmacists to ensure a thorough history is taken to determine the indication and patient’s expectations. Use of an open question, such as “As part of my checking process, please confirm the condition you are preventing with this vaccine”, may clarify the indication. Confirmation with the prescriber may be required when there is doubt about the vaccine’s purpose.

Patient age should not be the sole criteria on which a pharmacist makes a decision about these vaccines as adults may present a prescription for either indication. Adult vaccination against chickenpox may be more likely for unvaccinated adults who are healthcare workers, childhood educators and carers, or those working in long-term care facilities. Consideration should also be given to appropriateness for women of child-bearing age. The CMI recommend women should avoid pregnancy for one month after Varilrix® and three months after Varivax® and Zostavax®. *The Immunisation Handbook states that women of child-bearing age should avoid pregnancy for 28 days after vaccination with any varicella live attenuated vaccine.

Points of commonality and contrast between these vaccines include the following:

  • The volume of the vaccines. Varilrix (chickenpox), Varivax (chickenpox) and Shingrix® (shingles) vaccines are 0.5mL whereas Zostavax (shingles) vaccine has a volume of 0.65mL.
  • Varicella (chickenpox) vaccination requires two doses of the vaccine.
  • For herpes zoster (shingles), the treatment regime requires two doses of the Shingrix vaccine whereas only one dose of Zostavax vaccine is required.
  • Shingrix is approved for use in individuals 50 years and older, and individuals 18 years and over at risk of herpes zoster infection.
  • Zostavax is approved for use in individuals 50 years and older.
  • Live attenuated vaccines such as Zostavax, Varilrix and Varivax have contraindications for patients with current or recent immunocompromising conditions from either a primary or acquired medical condition or treatment. Given the vaccine is likely to be prescribed by active ingredient, ensure the patient does not have a contraindication to the administration of a live attenuated vaccine. Shingrix may be suitable, for shingles only, in such a circumstance. Pharmacists are encouraged to review the Product Information documents for contraindications and precautions to these vaccines.

*Practice Alert updated on 25 August 2022 

For immediate advice and incident support, call PDL on 1300 854 838 to speak with one of our Professional Officers. We are here to support our pharmacist members 24/7, Australia-wide.