Pensri Kosuwon

Reactogenicity and immunogenicity of reduced antigen content diphtheria–tetanus–acellular pertussis vaccine (dTpa) administered as a booster to 4–6 year-old children primed with four doses of whole-cell pertussis vaccine

A trial to compare the reactogenicity and immunogenicity of a reduced antigen content diphtheria-tetanus-acellular pertussis (dTpa) vaccine with diphtheria-tetanus-whole-cell pertussis (DTPw) vaccine was conducted in Thailand. Three hundred and thirty children aged 4-6 years, primed with four doses of DTPw, received a single injection of either dTpa or DTPw. There was a significantly lower incidence of local and general reactions following dTpa than DTPw (P<0.001). One month after vaccination, 99.4 and 100% of all subjects had protective anti-diphtheria and -tetanus titers, respectively. The vaccine response rate to pertussis antigens was similar in both groups, with 96.9% versus 92.5% for anti-pertussis toxin (PT), 96.9% versus 97.5% for anti-filamentous hemagglutinin (FHA) and 95.1% versus 90.8% for anti-pertactin (PRN) in the dTpa and DTPw groups, respectively. For anti-BPT, the vaccine response in the dTpa group was 29.6% versus 94.4% for DTPw. In conclusion, the dTpa vaccine was as immunogenic and significantly better tolerated than DTPw. The new dTpa vaccine could improve coverage for routine booster vaccination in children and provide a good replacement for DTP vaccines at 4-6 years of age.

Sixteen Years of Global Experience with the First Refrigerator-Stable Varicella Vaccine (Varilrix™)

Without vaccination, chickenpox (varicella) will affect almost every person in the world during their lifetime. The burden of disease due to varicella is often unrecognized. Varilrix™ is a varicella vaccine derived from the Oka strain of varicella virus. The vaccine, as a frozen formulation, was licensed for use in 1984 and was the first commercially available varicella vaccine. It subsequently became the first refrigerator-stable varicella vaccine; its development commenced in 1991 and it has been licensed for use since 1994. Varilrix™ is indicated for use in high-risk groups, potentially immunocompromised individuals, and healthy subjects in many countries. This article reviews data from extensive worldwide experience with the refrigerator-stable version of the vaccine, including information derived from its use in over 10 000 individuals participating in clinical trials investigating its immunogenicity, efficacy, effectiveness, and safety, as well as postmarketing data including its use in universal mass vaccination programs. Sixteen years of clinical and postmarketing experience with the same formulation represents the longest and most extensive experience with a refrigerator-stable varicella vaccine worldwide. Varilrix™, in conjunction with the trivalent measles-mumps-rubella vaccine Priorix™, has also been the basis for clinical development of the tetravalent measles-mumps-rubella-varicella vaccine (Priorix-Tetra™).

Relative Efficacy of AS03-Adjuvanted Pandemic Influenza A(H1N1) Vaccine in Children: Results of a Controlled, Randomized Efficacy Trial

Abstract Background. The vaccine efficacy (VE) of 1 or 2 doses of AS03-adjuvanted influenza A(H1N1) vaccine relative to that of 2 doses of nonadjuvanted influenza A(H1N1) vaccine in children 6 months to <10 years of age in a multinational study conducted during 2010–2011. Methods. A total of 6145 children were randomly assigned at a ratio of 1:1:1 to receive 2 injections 21 days apart of A/California/7/2009(H1N1)-AS03 vaccine at dose 1 and saline placebo at dose 2, 2 doses 21 days apart of A/California/7/2009(H1N1)-AS03 vaccine (the Ad2 group), or 2 doses 21 days apart of nonadjuvanted A/California/7/2009(H1N1) vaccine (the NAd2 group). Active surveillance for influenza-like illnesses continued from days 14 to 385. Nose and throat samples obtained during influenza-like illnesses were tested for A/California/7/2009(H1N1), using reverse-transcriptase polymerase chain reaction. Immunogenicity, reactogenicity, and safety were assessed. Results. There were 23 cases of confirmed 2009 pandemic influenza A(H1N1) (A[H1N1]pdm09) infection for the primary relative VE analysis. The VE in the Ad2 group relative to that in the NAd2 group was 76.8% (95% confidence interval, 18.5%–93.4%). The benefit of the AS03 adjuvant was demonstrated in terms of the greater immunogenicity observed in the Ad2 group, compared with the NAd2 group. Conclusion. The 4–8-fold antigen-sparing adjuvanted pandemic influenza vaccine demonstrated superior and clinically important prevention of A(H1N1)pdm09 infection, compared with nonadjuvanted vaccine, with no observed increase in medically attended or serious adverse events. These data support the use of adjuvanted influenza vaccines during influenza pandemics. Clinical Trials Registration. NCT01051661.