Immunogenicity of a human rotavirus vaccine (RIX4414) after storage at 37 °C for seven days.

AIM: The lyophilized formulation of the human rotavirus vaccine, RIX4414 (RotarixTM), is recommended to be stored at 2°C-8°C for optimal immunogenicity. In some settings with inadequate infrastructure for vaccine storage, unforeseen circumstances may cause cold chain breakage, resulting in the vaccine to be left at ambient temperatures. This study evaluated the heat stability of lyophilized RIX4414 vaccine in terms of immunogenicity when stored at tropical room temperature (37 °C) for 7 days before reconstitution. RESULTS: There was no statistically significant difference detected between RIX4414 vaccine stored at 2 °C-8 °C (Group RIX4414_control, n = 171) and that stored at 37 °C for 7 days (Group RIX4414_37 °C, n = 47) in terms of seroconversion rate and vaccine take. The anti-rotavirus IgA seroconversion rate 2 months post-Dose 2 was 84.7% (95% CI: 78.1%-90%) and 87.8% (95% CI: 73.8%-95.9%) in Groups RIX4414_control and RIX4414_37 °C, respectively. None of the 25 infants in placebo group seroconverted. The vaccine take in the respective vaccine groups were 88% (95% CI: 82.1%-92.5%) and 93.5% (95% CI: 82.1%-98.6%) and Geometric Mean Concentrations (GMCs) were 134.4 U/mL (95% CI: 104.5-172.9) and 163.7 U/mL (95% CI: 98.9-271.1). METHODS: Healthy infants aged 6-12 weeks, received two oral doses of either the RIX4414 vaccine stored at 2 °C-8 °C, RIX4414 vaccine stored at 37 °C for 7 days or placebo, according to a 0, 2 month schedule. Seroconversion rates in terms of anti-rotavirus IgA antibody levels (cut off: ≥ 20 U/mL by ELISA), anti-rotavirus IgA antibody GMCs and vaccine take were calculated 2 months post-Dose 2. CONCLUSION: Lyophilized RIX4414 vaccine stored at 37°C for 7 days before reconstitution has similar immunogenicity as the vaccine stored at 2 °C-8 °C. These results supported the use of RIX4414 in settings where the vaccine might be exposed to higher than the recommended storage temperatures.

An update of paediatric intussusception incidence in Singapore: 1997-2007, 11 years of intussusception surveillance.

INTRODUCTION: Understanding baseline epidemiology of intussusception (IS) in different geographical settings is important for the safety assessment of rotavirus vaccines. This paper presents IS surveillance data from Singapore between 1997 and 2007, including the period between November 2005 and December 2007 when rotavirus vaccines (primarily Rotarix) were available to newborns in Singapore. MATERIALS AND METHODS: Case ascertainment, collection, analyses and presentation of IS data was done as per recommendations of the Brighton Collaboration Working Group. For estimating the IS incidence rate in infants, live births for the years of the study were used as denominators, while for incidence in children age <2 years, the expected numbers of infant deaths occurring between 1 and 2 years of age was deducted from the combined live births for the 2 years, to obtain the denominator. RESULTS: The incidence of IS among children aged <1 year throughout this 10-year period was higher than the incidence of IS in children between 1 and 2 years of age. In 2005, 2006 and 2007, the incidence of IS per 100,000 was 39.9, 26.4 and 35.6 in children aged <1 year and 26.2, 23.8 and 28.7 in children <2 years. CONCLUSION: This IS surveillance study provides reassuring preliminary evidence that there is no increase in the incidence of IS in Singapore after the introduction of rotavirus vaccines (including Rotarix) in Singapore.

Women and vaccinations: From smallpox to the future, a tribute to a partnership benefiting humanity for over 200 years.

Vaccines were first developed in England over 200 years ago and have made a significant positive impact on human society since. Not often realized is the intimate relationship shared between vaccines and women. Women were key to the initial development of vaccines; some were even advocating the concept of protection against infectious disease through prior asymptomatic infection (by variolation) before the publication of the report of the first successful smallpox vaccination in 1798. Since that milestone, women have been important partners in the development of vaccines and advocates for their widespread introduction. Modern vaccine development would not be possible without the altruistic informed consent granted by many women for the participation of themselves or their children in vaccine clinical trials all over the world. Vaccines have rewarded women handsomely in return. Individual women benefit in many ways ranging from safer pregnancies to preventing cancers to attractive, unblemished skin. Some vaccines are even specifically designed to prevent diseases primarily affecting women such as cervical cancer. Vaccines also have offered societal benefits to women. These include better maternal health and fostering an environment more amenable to effective family planning. With these advances, women become more empowered and have access to better economic opportunities. The challenge of meeting the millennium development goals specifically targeted for women will be facilitated by vaccines. A better realization by women of the benefits of this partnership secured over the past 200 years will enable them to reap fully the rewards of the future.

Immunogenicity, reactogenicity and safety of human rotavirus vaccine (RIX4414) in Indian infants.

AIM: This study was undertaken to assess the immunogenicity, reactogenicity and safety of two doses of an oral live-attenuated human rotavirus vaccine, strain RIX4414 (Rotarix()) in an Indian setting. RESULTS: The seroconversion rate observed one month post-dose 2 in the RIX4414 group 58.3% [95% CI: 48.7; 67.4] was significantly higher when compared to the placebo group 6.3%; [95% CI: 2.5; 12.5]. The reactogenicity and safety profile was similar for both groups. PATIENTS AND METHODS: Healthy infants (N = 363), approximately eight weeks of age were enrolled to receive two doses of RIX4414 vaccine (n = 182) or placebo (n = 181) separated by one month. To assess the immune response, blood samples were taken before vaccination and one month post-dose 2 of RIX4414/placebo. Solicited symptoms were collected for eight-days post each dose and safety data was collected throughout the study. CONCLUSIONS: Two doses of RIX4414 (Rotarix()) were immunogenic, had a good safety profile and were well-tolerated when administered to healthy Indian infants. CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov; NCT00289172; eTrack 103792.

Immunogenicity, reactogenicity and safety of a diphtheria-tetanus-acellular pertussis-inactivated polio and Haemophilus influenzae type b vaccine in a placebo-controlled rotavirus vaccine study.

INTRODUCTION: In recent years, acellular pertussis combination vaccines have facilitated compliance with and coverage of the national immunisation programme in Singapore. This phase-II study (Rota-007) evaluated the immunogenicity, reactogenicity and safety of a DTPa-IPV/Hib combined vaccine when co-administered with a rotavirus vaccine. MATERIALS AND METHODS: A total of 2464 children aged 3 months were vaccinated with DTPa-IPV/Hib together with a randomised 1:3 ratio of either placebo (n=653) or 1 of 3 different formulations of a rotavirus vaccine. Blood samples were collected for immunogenicity analysis 1 month after the third DTPa-IPV/Hib vaccine dose in a subset of subjects (n = 640). Local and general reactogenicity and unsolicited adverse events were recorded during the follow-up after each vaccination. RESULTS: Serological analysis showed >95% response for all antigens in the co-administered DTPa-IPV/Hib vaccine, with no difference between the rotavirus vaccine and placebo groups. No differences in adverse events and reactogenicity were reported in the rotavirus vaccine and placebo groups. Only 0.2% of the subjects reported Grade 3 adverse events. Three subjects (from the vaccine groups) died during the study, which were assessed by the investigators as unrelated to vaccination. No deaths were reported in the placebo group. CONCLUSION: The combined DTPa- IPV/Hib vaccine is safe, well tolerated and highly immunogenic when given alone or coadministered with the rotavirus vaccine for infants in Singapore.

The epidemiology of paediatric intussusception in Singapore: 1997 to 2004.

INTRODUCTION: The world's first rotavirus vaccine, Rotashield or RRV-TV, was registered in the US in 1998, but withdrawn within a year because of an observed association with intussusception (IS). Surveillance for IS has consequently become important in safety monitoring of new-generation rotavirus vaccines during development. Post-marketing surveillance is also important, and requires the availability of local baseline epidemiology data on IS. MATERIALS AND METHODS: An eight-year study of IS in children under 2 years of age in Singapore was performed by retrospective review of admissions to KK Women's and Children's Hospital, the main paediatric hospital, from 1997 to 2001, followed by prospective surveillance of all hospitals from 2001 to 2004, using the case definition of the Brighton Collaboration Intussusception Working Group. RESULTS: The average IS incidence was 60 per 100,000 in under-ones, and 32 per 100,000 in under-twos, with a downward trend between 1999 and 2004. Ninety-two per cent of subjects were aged below one year, with 51% aged 6 months to 11 months. The mean age at which IS occurred increased from 6.4 months to 12.5 months over the study period. The male-to-female ratio was 1.3:1. No trend in IS numbers was observed over different months of the year. CONCLUSION: IS in Singapore shows no seasonality, but has demonstrated a trend of decreasing incidence in recent years. While highest in the first year of life, the risk of IS is increasing in the second year of life. Males have a slightly higher risk.

Evaluation of RIX4414, a live, attenuated rotavirus vaccine, in a randomized, double-blind, placebo-controlled phase 2 trial involving 2464 Singaporean infants.

BACKGROUND: At present, no rotavirus vaccine is commercially available for use worldwide. Hence, a live, attenuated monovalent vaccine was developed with human strain RIX4414 (G1P1A P[8] specificity). Vaccination trials involving infants are ongoing in developed and developing countries. METHODS: This study was a randomized, double-blind, placebo-controlled trial conducted at pediatric hospitals and polyclinics in Singapore for the evaluation of the immunogenicity, reactogenicity, and efficacy of 2 oral doses of RIX4414. In total, 2464 healthy infants (who were 11-17 weeks old when the first dose was administered, which is in accordance with the local immunization schedule) were enrolled to receive RIX4414 at 3 concentrations of virus (10(4.7), 10(5.2), or 10(6.1) focus-forming units) or placebo at 1-month intervals, concomitantly with routinely administered infant vaccines. RESULTS: The RIX4414 vaccine was highly immunogenic, and virtually all vaccine recipients (98%-100%) experienced "vaccine take" (i.e., a combined immunogenicity end point based on seroconversion and/or shedding of RIX4414 in postvaccination stool samples) after receipt of 2 doses at all 3 dosage levels. Depending on the virus concentration, the anti-rotavirus IgA seroconversion rate varied from 76% (95% confidence interval [CI], 68%-83%) to 91% (95% CI, 85%-95%). Two doses of RIX4414 were well tolerated, with no increase in high fever, severe diarrhea, or vomiting after either dose or with increased viral concentration, compared with placebo. There was no observed interference with routine vaccinations of infants when RIX4414 was coadministered. The calculated efficacy of RIX4414 against rotavirus gastroenteritis was 82% (P = .046); however, this result was considered to be of limited conclusive value because of the low number of rotavirus gastroenteritis episodes identified during the follow-up period. CONCLUSIONS: The live, attenuated rotavirus vaccine (RIX4414) was well tolerated and highly immunogenic in Singaporean infants. The immunogenicity of routinely administered infant vaccines was not impaired by concomitant administration of RIX4414 vaccine.

Comparative study of the reactogenicity of a three-component acellular pertussis vaccine and whole-cell pertussis vaccine administered to healthy Singaporean infants.

The objective of this study was to assess and compare the reactogenicity of GlaxoSmithKline (GSK) Biologicals' diphtheria-tetanus-tricomponent acellular pertussis vaccine (DTPa) and the locally used combined diphtheria-tetanus-whole-cell pertussis vaccine (DTPw) as a primary vaccination course in healthy infants at the age of 3, 4 and 5 months. A phase IV, single-blinded, randomized comparative clinical study involved one hundred and eighty healthy infants with two study groups in a 2:1 ratio to receive either DTPa or DTPw vaccine which were administered intramuscularly at the right anterior-lateral aspect of the thigh. The incidence and intensity of local solicited symptoms such as pain, redness and swelling at injection site and general solicited symptoms such as fever and fussiness were evaluated. Serious adverse events were followed for one month after each vaccination. The overall incidence of local and general symptoms was significantly higher in the group receiving locally used DTPw vaccine as compared to the group receiving GSK DTPa vaccine. Solicited local symptoms, pain (47.4% vs 15.1%), redness (95.9% vs 84.9%) and swelling (46.2% vs 18.5%), were reported more frequently in the group receiving DTPw vaccine than in the group receiving DTPa vaccine. Fever (> or = 37.5 degrees C) (52% vs 14.6%) and fussiness (60.8% vs 33.6%) were also more commonly reported in the DTPw group. There were six serious adverse events reported (4 with DTPw and 2 with DTPa). None of them related to the study vaccines, as considered by the investigators. Thus it was found that GSK Biologicals' DTPa vaccine was significantly less reactogenic as compared to the locally used DTPw vaccine manufactured by Commonwealth Serum Laboratories when administered as a 3-dose primary vaccination course to healthy infants at the age of 3, 4 and 5 months in Singapore.

Active immunization against hepatitis A in dialysis patients.

BACKGROUND: This study investigated the feasibility, immunogenicity, and reactogenicity of hepatitis A vaccination in end-stage renal failure patients who were on chronic intermittent haemodialysis. METHODS: Forty-three subjects were vaccinated with an inactivated hepatitis A vaccine according to a 0-, 1-, and 6-month immunization schedule. Two groups were established who received the vaccine either intramuscularly (group A, n=30) or subcutaneously (group B, n=13). RESULTS: All patients in group A and 12/13 in group B developed antibodies against hepatitis A. The geometric mean titres (GMT) were high and similar to those observed in healthy subjects. There was a tendency to higher GMT in the group who received the vaccine subcutaneously. No clinically significant adverse events were observed, and the liver enzyme profile showed no abnormalities. CONCLUSIONS: We showed that hepatitis A vaccination of dialysis patients is feasible, well tolerated and immunogenic and that the vaccine can be given subcutaneously in those patients where intramuscular administration is contra-indicated.