Vaccine myopia: adult vaccination also needs attention

I read with interest the call by Menzies and colleagues1 for revitalised efforts to vaccinate a higher proportion of the adult Australian population against common infectious diseases. At present, the aim of the adult component of the National Immunisation Program is to protect against Streptococcus pneumoniae and the two viruses that cause influenza and herpes zoster — all prevalent pathogens in our environment.

In addition to infections derived in Australia, adults are more likely than children to be the focus of imported cases of infection. Exposure of adults to, for instance, tropical infectious diseases, including those transmitted by biting insects (ie, dengue, yellow fever, chikungunya and Zika viruses, malaria, etc), will be far greater than that of juveniles. This is because adults have more reason to travel overseas and typically undertake more trips than children do.2

Vaccine uptake among travellers is mixed, and there are groups that are not sufficiently vaccinated, including people who travel overseas to visit friends and relatives (VFR). These so-called VFR travellers are more likely to consider themselves at low personal risk or threat when travelling to their country of origin, stemming from a sense of familiarity with the destination country and its infectious disease risks.3 Cultural beliefs and language barriers are also important factors associated with suboptimal uptake of pre-travel advice among VFR travellers.

While infants accompany their parents for holidays and to visit family abroad, intercontinental travel for business and educational opportunities is largely restricted to adults.4 For typical short stay business trips, rather than for holidays lasting an extended period, it is tempting to neglect being up to date with vaccinations.2 In this instance, for the busy business flyer — often a last-minute traveller — the risk aversion to illness may be suppressed by avoidance of the perceived hassle of immunisation.

Travel acts as a vector for spread of infection and many outbreaks are imported into Australia through overseas trips; nevertheless, travellers frequently neglect to seek pre-travel health advice.5 Improving rates of travel vaccination, especially in adults, is one area of focus that may help infectious disease control efforts nationally.