National serosurvey of cytomegalovirus in Australia

Fifty-seven per cent of Australians are seropositive for CMV, with over half of seropositive individuals being infected by one year of age.

What’s known?

• Cytomegalovirus (CMV) infections are common and usually asymptomatic in otherwise healthy children and adults.
• CMV has a worldwide distribution, infecting between 40% and 90% of adults, leading to lifelong latent infection.
• Following the implementation of universal rubella immunization programs, CMV has become a common cause of intrauterine infection, with between 0.3 and 2.4% of neonates becoming infected in different countries.
• There are several promising candidate vaccines against CMV in various stages of preclinical and clinical testing, including recombinant vaccines, live attenuated vaccines, and chimeric vaccines.
• The potential benefits of a CMV vaccine would include reduced transmission to pregnant women and less CMV disease due to primary infection or reactivation in organ transplant recipients and the immunosuppressed.

What’s new?

• This study aimed to determine the seroprevalence of CMV in Australia in relation to age and sex.
• A total of 3,593 serum samples were tested for CMV seroprevalence as part of the National Centre for Immunization Research and Surveillance of Vaccine Preventable Diseases (NCIRS) serosurveillance program from people between 1 and 59 years of age.
• The seroprevalence of CMV in the population tested was 57% (95% CI, 55.2 to 58.6%), with an overall association identified between seroprevalence and increasing age.
• For the groups of children aged 1 to 2 and 3 to 4 years, the recorded seroprevalences were 38% (95% CI, 32.2 to 44.3%) and 39% (95% CI, 34.0 to 44.5%), respectively.
• There was little overall difference in seroprevalence between males and females (51% and 54% seropositive, respectively).
• For women, a significant rise in CMV seroprevalence occurred between the group aged 30 to 34 years and that aged 35 to 39 years, which may be explained by motherhood and the fact that women in these age groups have close contact with young children, who may act as a vehicle for transmission.
• The authors suggest that, for a universal vaccination program to have maximal impact, the vaccine would need to be delivered to infants and have a long duration of protective efficacy. If the duration was only brief, a vaccine given just before pregnancy would be advised, or, if the vaccine had a medium duration of efficacy (5 years), regular boosters could be given throughout childbearing years.