Vaccination against Respiratory Virus may offer considerable public health benefit to Kenyan children

According to a study in the May 26, issue of the Journal of the American Medical Association (JAMA), vaccination against the RSV virus may offer considerable public health benefit to Kenyan children.

James A. Berkley, F.R.C.P.C.H., of the Kenya Medical Research Institute (KEMRI) and the University of Oxford, and colleagues conducted a study to examine the viruses causing severe pneumonia among infants and children at a rural Kenyan district hospital using comprehensive and sensitive molecular diagnostic techniques. Whilst it is well known that many pneumonias are caused by bacteria such as Streptococcus pneumonia, for which vaccines are available, upto now, much less attention has been given to pneumonia caused by viruses.

Participants were 759 children aged 1 day to 12 years who were admitted to Kilifi District Hospital with severe pneumonia from January 1, 2007 through December 31, 2007. For comparison, infants and children who presented to the hospital with mild upper respiratory tract infection but were not admitted and well infants and children attending for immunization had their nasal wash samples obtained and analyzed for the presence of the respiratory viruses.

Participants were 759 children aged one day to 12 years who were admitted to Kilifi District Hospital with severe pneumonia from January 1, 2007 through December 31, 2007. For comparison, infants and children who presented to the hospital with mild upper respiratory tract infection but were not admitted and well infants and children attending for immunization, had their nasal wash samples obtained and analysed for the presence of respiratory viruses.

The researchers found that Respiratory Syncitial Virus (RSV) was the most commonly detected virus, present in 260 admissions with severe pneumonia (34%) and in 192 of 453 of the infants under year of age (42%). Other respiratory viruses were also detected in 219 admissions (29%), the most common being Human coronavirus 229E (6.7%), Influenza type A (5.8%), Parainfluenza type 3(3.8%), Human adenovirus (3.8%), and Human metapneumovirus (3.0%).

The authors noted that RSV was detected in 5% of the well control participants, compared to 34% in those admitted with severe pneumonia, which suggests that RSV is strongly associated with severe pneumonia, and the commonest identified cause in this setting. These findings offer support that RSV vaccination may offer considerable public health benefit. There was no evidence to suggest that vaccination for other viruses would significantly reduce the burden of pneumonia, since other viruses were as common in the well control participants (22% in those admitted with severe or very severe pneumonia and 23% in well control participants attending for immunisation).

''In summary, our study of the occurence of respiratory viruses in children admitted with clinical syndromes of severe or very severe pneumonia to a rural district hospital in coastal Kenya has identified more than 50% of case participants with a detectable virus in whom RSV was clearly predominant. We estimate that the prevention of RSV-associated severe pneumonia might reduce all-cause clinically severe or very severe pneumonia admissions to the Kilifi District Hospital by one-third. This contrasts with no evidence to suggest a marked effect on such admissions would occur from teh prevention of any other respiratory virus, with the possible exemption of Influenza type A, which may also occur in epidemics. Further molecular-based studies of respiratory virus etiology of severe pneumonia over longer periods and in multiple settings in sub-Saharan Africa are needed,'' the authors conclude.

The leading cause of childhood death in sub-Saharan Africa is pneumonia. ''The main means for controlling disease and death due to pneumonia are infant vaccination and case management. Thus, establishing the contribution to severe disease of individual pathogens and vaccine efficacy in infancy are essential to reducing the burden of disease,'' the authors write.

Editor's note: Please see the attached article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support etc. (JAMA.2010;303(20):2051-2057. Available pre-embargo to the media at www.jamamedia.org)

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Justa Wawira, Head of External Relations

KEMRI-Wellcome Trust Research Programme

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Author contacts for commentary

James A. Berkley, F.R.C.P.C.H., Email: JBerkleykilifi [dot] kemri-wellcome [dot] org

Notes for Editors

The Kenya Medical Research Institute (KEMRI) is a Kenya government parastatal with the responsibility for health research to improve the health of Kenyans. It is one of the most well developed national research institutes in Africa, with a network of centres across Kenya such as the Centre for Geographic Medicine Research Coast (CGMR-C) that is home to the KEMRI-Wellcome Trust Research Programme. The Programme was formally established in 1989 and is a partnership between KEMRI, Oxford University and the Wellcome Trust. It conducts basic, epidemiological and clinical research in parallel, with results feeding directly into local and international health policy, and aims to expand the country's capacity to conduct multi-disciplinary research that is strong, sustainable and internationally competitive. Read more: www.kemri-wellcome.org

The Wellcome Trust is a global charity dedicated to achieving extra ordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust's breadth of support includes public engagement, education and the application of research to improve health. It is independent of both political and commercial interests. Read more: www.wellcome.ac.uk