Use of pre-travel vaccine-preventable disease serology as a screening tool to identify patients in need of pre-travel vaccination: a retrospective audit.

Background: Vaccination is a safe and effective public health intervention that not only protects individual travellers from vaccine-preventable diseases (VPDs), but prevents them from becoming a source of disease in their destination and on their return. Obtaining an accurate vaccination history from travellers during a pre-travel review can be difficult; serology may be used to identify patients who are non-immune to specific diseases in order to guide vaccination requirements. Clinically relevant data about the usefulness of serology in this setting are lacking. We performed a retrospective audit of pre-travel VPD serology requested by practitioners of a busy community-based travel clinic.

Methods: All serological results for measles, mumps, rubella, varicella zoster virus, hepatitis A and B requested over a 5-year period were extracted and analysed. Results were stratified by gender and year of birth and compared using Stata.

Results: Four thousand four hundred and fifty-one serological assays from 1445 individual were assessed. Overall, 47% of patients tested had at least one negative serological result. High rates of seropositivity for measles, mumps and rubella were seen in those born prior to 1966 but >10% of travellers born after 1966 lacked serological evidence of protection against these diseases. Hepatitis A and B serological results revealed broadly lower rates of immunity in our community likely reflecting the absence of these vaccines from historical vaccine protocols.

Conclusions: Serology can be a useful tool in the identification of non-immune travellers to enable targeted vaccination prior to travel. We recommend that travel health clinicians assess patients' vaccination and infection histories, and strongly consider serology or vaccination where there is doubt about immunity. This will help protect the traveller and prevent importation of disease into destination or home communities.