Children show protected immunity from pandemic flu vaccine one year later
News release from NETSCC, HTA
31 January 2012
Results of a follow-up trial have shown that children who received two doses of the H1N1 pandemic influenza vaccine split-virion containing AS03B adjuvant showed lasting protection from the flu one year later.
This is according to research published by the National Institute for Health Research Health Technology Assessment (NIHR HTA) programme.
In 2009 the UK Government purchased two pandemic influenza vaccines, a non-adjuvanted whole virion vaccine and an adjuvanted (AS03B) split-virion vaccine. Children in the UK were offered the adjuvanted H1N1 pandemic influenza vaccine in the 2009/10 influenza season. As the pandemic influenza virus continued to circulate in 2010/11, clinicians and parents wanted to know whether these children were still protected and how they responded to this virus.
In a previous study researchers, led by Professor Andrew Pollard of the University of Oxford, followed up on children aged six months to 12 years who had received the 2009 vaccine and compared the two pandemic influenza vaccines. The study showed that the AS03B adjuvant split-virion vaccine produced a marked immune response, particularly in the children under three years old, although it resulted in more injection-site reactions and fever.
This follow-up trial measured antibody levels one year after vaccination. Nearly all children who received two doses of the split-virion AS03B adjuvant H1N1 pandemic influenza vaccine had antibody levels deemed protective one year later. Children who received two doses of non-adjuvanted whole-virion vaccine had lower antibody levels, but many were still above the protective thresholds.
In addition, redness and injection-site symptoms graded as severe were reported more frequently in children under 5 years old who had previously received the split-virion, than in those who had been given the whole-virion vaccine.
When children were given a single dose of the 2010/11 vaccine they showed a marked response to the H1N1 component of the vaccine they had received one year earlier. This showed in both vaccines given in 2009. It was also generally well tolerated, although provoked a feverish response in 13-18 per cent of children under five years old.
Professor Pollard commented; “The inclusion of the AS03B adjuvant has resulted in an antigen-sparing vaccine producing a marked antibody response, which persists a year after vaccination. Although antibody persistence beyond one year remains unknown, in these children, administration of the vaccine containing the pandemic strain as one component, boosted the antibody titre and was well tolerated”.
Approximately 323 children aged six months to 12 years were enrolled in this follow-up study and 318 were included in the analysis of continued immunity. At the first visit, a blood sample was taken to assess persistence of immunity. A single dose of trivalent seasonal influenza vaccine was given by intra-muscular injection and a second blood sample was taken three weeks later. A diary card was used to record the following information daily for the first seven days after vaccination; axillary temperature, injection site reactions, systemic symptoms and anti-pyretic medication.
Notes for editors
1. The National Institute for Health Research Health Technology Assessment (NIHR HTA) Programme funds research about the effectiveness, costs, and broader impact of health technologies for those who use, manage and provide care in the NHS. It is the largest NIHR programme and publishes the results of its research in the Health Technology Assessment journal, with over 600 issues published to date. The journal’s 2011 Impact Factor (4.255) ranked it in the top 10% of medical and health-related journals. All issues are available for download, free of charge, from the website. The HTA Programme is funded by the NIHR, with contributions from the CSO in Scotland, NISCHR in Wales, and the HSC R&D Division, Public Health Agency in Northern Ireland. www.hta.ac.uk.
2. The National Institute for Health Research (NIHR) is funded by the Department of Health to improve the health and wealth of the nation through research. Since its establishment in April 2006, the NIHR has transformed research in the NHS. It has increased the volume of applied health research for the benefit of patients and the public, driven faster translation of basic science discoveries into tangible benefits for patients and the economy, and developed and supported the people who conduct and contribute to applied health research. The NIHR plays a key role in the Government’s strategy for economic growth, attracting investment by the life-sciences industries through its world-class infrastructure for health research. Together, the NIHR people, programmes, centres of excellence and systems represent the most integrated health research system in the world. For further information, visit the NIHR website (www.nihr.ac.uk).
Paul Davey, Programme Manager (Communications)
Telephone: 02380 595 4309, Email: P.A.Davey@southampton.ac.uk