Serological testing before zoster vaccination is recommended for some people

It is not necessary to have serological evidence of immunity to varicella-zoster virus (VZV) or a history of previous varicella infection before routine administration of zoster vaccine. 

However, serological testing before zoster vaccination is recommended if the person receiving the vaccine:

• has HIV (see People with HIV in Contraindications and precautions)
• has an uncertain level of immunocompromise and there is potential risk for adverse events identified in pre-vaccination screening (see People with mild to moderate immunocompromising conditions)

People who are immunosuppressed and have negative VZV IgG should not receive Zostavax. See also Contraindications and precautions.

The interpretation of serology for varicella (chickenpox) is difficult, as there is no serological correlate of protection, but a positive result indicates past exposure (from either natural infection or vaccination) and more than 97% of  people in Australia are seropositive to VZV by 30 years of age,¹⁵ even if they cannot recall having varicella at a younger age. In some small studies, high-dose VZV-containing vaccine (comparable to Zostavax) was given to healthy VZV-seronegative adults and previously infected adults. The limited data suggest that the vaccine was well tolerated and immunogenic in seronegative people,^16,17 If an individual does not have evidence of previous VZV natural infection and is seronegative, very severe outcomes may occur in immunocompromised individuals.¹⁸ A cautious approach with detailed individual clinical assessment is required prior to administration of the Zostavax vaccine.