Recent years have seen important steps forward in CMV research, both in the UK and around the world, with studies planned or underway across the entire spectrum of the infection, from diagnosis and screening, through to transmission, treatment and prevention. Yet important gaps in our understanding still exist and the UK is very much at the forefront
of finding the answers.
Identifying and treating CMV infection
Much of the research in the UK has focussed on diagnosis and treatment. Hearing loss at birth is one of the most common symptoms of CMV. Yet some CMV babies who fail their newborn hearing screen are not diagnosed with CMV in time to start antiviral treatment, which must happen in the first month of life in order to limit further deterioration of hearing.
To address this issue, a series of studies in the UK (BEST1 and BEST2) has explored the benefits and feasibility of integrating testing for CMV within the existing newborn hearing screening programme. Results from these studies have shown that testing for CMV is both acceptable to 97 per cent of parents, and feasible in ‘real life’ practice.31 Newborn hearing screeners felt confident in performing the tests and were able to screen around eight out of every ten babies referred for further hearing assessment.32
Research in this area is emerging in ever more innovative directions, including development of an easy to use test to diagnose CMV that uses nanotechnology – a high tech yet low cost device that could enable even more babies to be tested and diagnosed.
Educating pregnant women about CMV can reduce infection in pregnancy
The picture on CMV treatment for newborns is evolving rapidly. A US/UK collaboration reporting in 2013 published evidence on the benefits and risks of oral antiviral medicines and showed that longer treatment could result
in improved outcomes compared to shorter treatment.33 In addition, further research is now underway that will explore the benefits of oral antiviral treatment for children with sensorineural hearing loss and congenital CMV up to the age of 4 years. This could mean that more children have the option of treatment, which is especially important for those who develop hearing problems later on.
Where to next?
Research has come a long way in recent years, yet some important knowledge gaps remain.
Research has come a long way in recent years, yet some important knowledge gaps remain. Currently several early studies are looking at new approaches in treatment, such as immunoglobulins and antiviral medicines,34,35,36 as well as the ways of reducing transmission from an infected mother to her unborn child.34 Clearly, while some of this research appears promising, we need results from larger randomised studies to confirm initial findings.
In addition, we need to know more about the overall impact of this infection and where we should focus our efforts in combating it. The Life Study—the largest ever UK-wide cohort study of babies and young children—will look at the burden of disease of congenital CMV and assess which women get infected or re-infected.We also need to know which babies with infection at birth are more likely to have long-term disease, can we predict those destined for hearing loss? And do babies with less severe symptoms of disease receive the same benefits from treatment as those who do not?
We know that, ultimately, preventing CMV depends on developing a vaccine. There is a clear need for more clinical trials of potential vaccine candidates.
So while we wait for the answers to these questions, our focus should be on two things: diagnosis and education.
First, we have shown that babies who are at risk of CMV-related hearing loss can be tested for CMV quickly and easily within the NHS. We now need a larger-scale implementation study to fully assess the potential costs and savings, so that NHS commissioners have the information they need to make decisions about improving neonatal pathways.
Second, there exists a substantial body of international evidence showing that educating pregnant women about CMV can reduce infection in pregnancy. We know education works, we now need to explore how CMV education can most effectively be delivered within the NHS.
Professor Mike Sharland
Professor of Paediatric Infectious Diseases,
St George’s University Hospitals NHS Foundation Trust