Short- and long-term impact of vaccination against cytomegalovirus: a modeling study

BACKGROUND

Infection with cytomegalovirus (CMV) is highly prevalent worldwide and can cause severe disease in immunocompromised persons and congenitally infected infants. The disease burden caused by congenital CMV infection is high, especially in resource-limited countries. Vaccines are currently under development for various target groups.

METHODS

We evaluated the impact of vaccination strategies and hygiene intervention using transmission models. Model parameters were estimated from a cross-sectional serological population study (n=5179) and a retrospective birth cohort (n=31,484), providing information on the age- and sex-specific CMV prevalence and on the birth prevalence of congenital CMV (cCMV).

RESULTS

The analyses show that vertical transmission and infectious reactivation are the main drivers of transmission. Vaccination strategies aimed at reducing transmission from mother to child (vaccinating pregnant women or women of reproductive age) can yield substantial reductions of cCMV in 20 years (31.7-71.4% if 70% of women are effectively vaccinated). Alternatively, hygiene intervention aimed at preventing CMV infection and re-infection of women of reproductive age from young children is expected to reduce cCMV by less than 2%. The effects of large-scale vaccination on CMV prevalence can be substantial, owing to the moderate transmissibility of CMV at the population level. However, as CMV causes lifelong infection, the timescale on which reductions in CMV prevalence are expected is in the order of several decades. Elimination of CMV infection in the long run is only feasible for a vaccine with a long duration of protection and high vaccination coverage.

CONCLUSIONS

Vaccination is an effective intervention to reduce the birth prevalence of cCMV. Population-level reductions in CMV prevalence can only be achieved on a long timescale. Our results stress the value of vaccinating pregnant women and women of childbearing age and provide support for the development of CMV vaccines and early planning of vaccination scenarios and rollouts.

Bacterial colonization of handheld devices in a tertiary care setting: a hygiene intervention study

Background

Tablet computers are increasingly being used in hospital patient care and are often colonized with important human pathogens, while the impact of disinfection interventions remains controversial.

Method

In a prospective hygiene intervention study we consecutively sampled tablet computers exclusively used in a high-resource general internal medicine tertiary care setting with high routine hygiene measures. Our aim was to examine the change in colonizing bacteria on tablet computers before and after the introduction of a mandatory twice daily tablet disinfection intervention. Microbial identification was performed by conventional culture, and the association of bacterial colonization with the intervention was investigated using logistic regression.

Results

In a total of 168 samples we identified colonizing bacteria in 149 (89%) of samples. While the most commonly identified species were normal skin bacteria, Staphylococcus aureus found in 18 (11%) of samples was the most frequent potential pathogen. We did not detect any Enterococci or Enterobacteriaceae. The disinfection intervention was associated with substantially less overall bacterial colonization (odds ratio 0.16; 95%-CI 0.04–0.56), while specific colonization with Staphylococcus aureus was only slightly decreased (odds ratio 0.46; 95%-CI 0.16–1.29).

Conclusion

Our results indicate that a twice daily disinfection can still substantially reduce bacterial colonization of in-hospital tablet computers used in a high-resource and high hygiene setting.