Immunogenicity and Safety of the AS04-adjuvanted Human Papillomavirus-16/18 Cervical Cancer Vaccine in Malaysian Women Aged 18-35 years: A Randomized Controlled Trial

INTRODUCTION

Cervical cancer is the third most common cancer in women worldwide. The HPV-16/18 AS04- adjuvanted vaccine (Cervarix©) has previously been shown to be highly immunogenic with a clinically acceptable safety profile. This phase IIIb, double-blind, randomized (1:1) and placebo controlled trial (NCT00345878) was designed to evaluate the vaccine immunogenicity against HPV-16 and HPV-18 as well as its safety and reactogenicity in Malaysian women.

METHODS

Healthy women aged 18-35 years received intramuscularly three doses of either the vaccine (HPV group) or aluminium hydroxide (ALU group) at 0, 1, and 6 months. Antibody titers were measured by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 271 eligible subjects were enrolled and 266 subjects completed the study. Initially seronegative subjects in the HPV group showed 100% seroconversion one month post-dose-3 for anti HPV-16 and anti-HPV-18 antibodies with geometric mean titers of 11107.5 (95% CI: 9727.3-12683.4) EL.U/mL and 4273.5 (95% CI: 3771.8-4841.9) EL.U/mL, respectively. Over 96% of subjects in both groups received all three vaccine doses. Solicited local (pain) and general symptoms (myalgia, fatigue, arthralgia and headache) were commonly reported in both HPV and ALU groups. Eight serious adverse events were reported throughout the study (five in the HPV group; three in the ALU group), all considered by investigators to be unrelated to vaccination.

CONCLUSION

The HPV-16/18 AS04-adjuvanted vaccine was immunogenic and generally well tolerated in Malaysian women aged 18-35 years.

Cross-clade immunogenicity and safety of an AS03A-adjuvanted prepandemic H5N1 influenza vaccine in Hong Kong

OBJECTIVE

To present Hong Kong'Äìspecific data from a large Asian population (also involving Thailand, Singapore, and Taiwan) on safety and manufacturing consistency across four AS03(A)-adjuvanted H5N1 vaccine formulations in terms of immune response against the A/Vietnam/1194/2004 strain. Immunogenicity against the heterologous A/Indonesia/05/2005 strain was also assessed. NCT Number: 00449670.

DESIGN

Prospective, observer-blind study.

SETTING

Out-patient clinic of a tertiary hospital in Hong Kong.

PARTICIPANTS

A total of 360 subjects aged 18 to 60 years were randomised into six groups to receive two doses (21 days apart) of the study vaccine.

INTERVENTIONS

One of the four adjuvanted formulations (3.75 microgram H5N1 haemagglutinin [HA]+AS03(A)) of the vaccine (H5N1-AS03(A)) or one of the two non-adjuvanted (3.75 microgram H5N1 [HA]) formulations of the vaccine (H5N1-DIL).

MAIN OUTCOME MEASURES

Blood samples collected before vaccination and 21 days after each vaccine dose were analysed using haemagglutination-inhibition and neutralisation assays. Solicited, unsolicited, and serious adverse events were recorded.

RESULTS

Manufacturing consistency across all four vaccine formulations was demonstrated. After two doses, the AS03(A)-adjuvanted prepandemic influenza vaccine demonstrated high seroprotection rates against the A/Vietnam/1194/2004 strain (95.8%) and good immunogenicity against the heterologous A/Indonesia/05/2005 strain (45.7%), as compared to the non-adjuvanted vaccine (4.6% and 1.5%, respectively). The seroconversion rates induced by the adjuvanted formulations in terms of viral neutralising antibodies against the two strains were much higher than those induced by the non-adjuvanted formulations. There were no safety concerns for any of the adjuvanted vaccine formulations.

CONCLUSIONS

The AS03(A)-adjuvanted H5N1 prepandemic influenza vaccine demonstrated good immunogenicity and an acceptable safety profile in Hong Kong.

Influenza and seasonal influenza vaccination among diabetics in Singapore: knowledge, attitudes and practices

INTRODUCTION

Seasonal influenza vaccination is recommended for diabetics; however, the vaccination uptake rate among diabetics remains low. This study explored the knowledge, attitudes and practices among diabetics in Singapore with regard to influenza and influenza vaccination.

METHODS

A survey was conducted among type 1 and 2 diabetes mellitus patients who attended three management centres of the Diabetic Society of Singapore in January 2007. The pilot-tested questionnaire covered influenza and influenza vaccination in terms of the patient demographics, medical history and knowledge, attitudes and practices.

RESULTS

A total of 307 diabetics participated in the study. Of these, 139 (45.3 percent) claimed to know the difference between influenza and the common cold, while 98 (31.9 percent) and 18 (5.9 percent) participants thought that influenza vaccines protected against all influenza strains and provided lifelong immunity, respectively. 247 (80.4 percent) participants were aware that they were at a moderate or higher risk for influenza-related complications, while 181 (58.9 percent) considered vaccination to be effective in preventing influenza and its complications. Only 94 (30.6 percent) participants were previously vaccinated. Among those unvaccinated, 117 (54.9 percent) did not think vaccination was necessary, while 104 (48.8 percent) had never considered it. As observed from the multivariate analysis, income was a key predictor of influenza vaccination. While 241 (78.5 percent) participants cited healthcare professional advice as the main guiding factor for getting vaccinated, 199 (64.8 percent) had never been advised on influenza vaccination. Of the 108 (35.1 percent) participants who had received previous advice on influenza vaccination, the majority had received it from their healthcare professionals.

CONCLUSION

Uptake of influenza vaccination among diabetics in Singapore is low, and the key predictor is income. Perception and knowledge are the main barriers, and hence, healthcare professionals should educate and encourage vaccination among diabetics.

Reactogenicity and immunogenicity of a live-attenuated refrigerator-stable varicella vaccine (OKA strain) in healthy seronegative subjects age 10 months to 12 years

This study assessed the immunogenicity and reactogenicity of a live-attenuated varicella vaccine (Oka strain), Varilrix in Indonesian children age 10 months to 12 years. A total of 300 seronegative subjects were stratified into three age subgroups (10 months to < 3 years, 3 years to < 7 years and 7 to 12 years) and all received a single-dose of Oka strain varicella vaccine. One solicited local symptom (injection site soreness) was reported during the 43-day post-vaccination follow-up period. Fever (29/295; 10%) was more prevalent than rash (3/295; 1%) but the incidence of grade 3 fever (defined as axillary temperature of >39 degrees C) was infrequent. No grade 3 unsolicited events and no serious adverse events were reported. The vaccine proved to be immunogenic in all age groups; all but one subject seroconverted for anti-varicella antibodies 43-days post-vaccination. This study demonstrated that the live-attenuated varicella vaccine (Oka strain) was well tolerated and immunogenic with no safety issues when administered as a single dose primary vaccination to healthy, seronegative Indonesian subjects age 10 months to 12 years.

Vaccination greatly reduces disease, disability, death and inequity worldwide

In low-income countries, infectious diseases still account for a large proportion of deaths, highlighting health inequities largely caused by economic differences. Vaccination can cut health-care costs and reduce these inequities. Disease control, elimination or eradication can save billions of US dollars for communities and countries. Vaccines have lowered the incidence of hepatocellular carcinoma and will control cervical cancer. Travellers can be protected against "exotic" diseases by appropriate vaccination. Vaccines are considered indispensable against bioterrorism. They can combat resistance to antibiotics in some pathogens. Noncommunicable diseases, such as ischaemic heart disease, could also be reduced by influenza vaccination. Immunization programmes have improved the primary care infrastructure in developing countries, lowered mortality in childhood and empowered women to better plan their families, with consequent health, social and economic benefits. Vaccination helps economic growth everywhere, because of lower morbidity and mortality. The annual return on investment in vaccination has been calculated to be between 12% and 18%. Vaccination leads to increased life expectancy. Long healthy lives are now recognized as a prerequisite for wealth, and wealth promotes health. Vaccines are thus efficient tools to reduce disparities in wealth and inequities in health.

Vaccination greatly reduces disease, disability, death and inequity worldwide

In low-income countries, infectious diseases still account for a large proportion of deaths, highlighting health inequities largely caused by economic differences. Vaccination can cut health-care costs and reduce these inequities. Disease control, elimination or eradication can save billions of US dollars for communities and countries. Vaccines have lowered the incidence of hepatocellular carcinoma and will control cervical cancer. Travellers can be protected against "exotic" diseases by appropriate vaccination. Vaccines are considered indispensable against bioterrorism. They can combat resistance to antibiotics in some pathogens. Noncommunicable diseases, such as ischaemic heart disease, could also be reduced by influenza vaccination. Immunization programmes have improved the primary care infrastructure in developing countries, lowered mortality in childhood and empowered women to better plan their families, with consequent health, social and economic benefits. Vaccination helps economic growth everywhere, because of lower morbidity and mortality. The annual return on investment in vaccination has been calculated to be between 12% and 18%. Vaccination leads to increased life expectancy. Long healthy lives are now recognized as a prerequisite for wealth, and wealth promotes health. Vaccines are thus efficient tools to reduce disparities in wealth and inequities in health.

Immunogenicity and safety of combined diphtheria tetanus whole cell pertussis hepatitis B/ Haemophilus influenzae type b vaccine in Indian infants

OBJECTIVE

To evaluate the immunogenicity of the Hepatitis B and Haemophilus influenzae type b components and the overall safety and reactogenicity of the DTPw-HBV/Hib vaccine when given as primary vaccination to Indian infants.

DESIGN AND METHODS

At 3 centers in India, 225 healthy infants (who had received HBV at birth) received three doses of DTPw-HBV/Hib vaccine at 6, 10 and 14 weeks of age. Serum anti-HBs and anti-PRP antibody levels were measured prior to vaccination and one month post dose 3. Solicited local and general symptoms reported during the 4-day follow-up period and unsolicited adverse event reported during the 30-day follow-up period after each dose were recorded. Serious adverse events were recorded throughout the study.

RESULTS

A total of 219 subjects completed the study. 2.7% and 11.5% of all administered doses led to redness and swelling >20 mm, respectively; only 3.6% of doses were followed by severe pain (cried when limb was moved, spontaneously painful) within 4 days after vaccination. Fever exceeding 39.5C was recorded following only one dose in one subject. The percentage of doses followed by severe solicited general symptoms (symptoms that prevented normal activity) did not exceed 0.8%. Two SAEs were reported, neither of which were considered as related to vaccination. One month post-dose 3, all subjects had seroprotective antiPRP antibody concentrations (> or =0.15 microgram/mL) and 98.6% had concentrations > or =1 microgram/mL; 99% were seropositive for antiHBs (concentrations > or = 3 mIU/mL) and 99% were seroprotected (concentrations > or = 10 mIU/mL).

CONCLUSION

The combination DTPw-HBV/Hib vaccine is immunogenic (for the antigens tested), safe and well tolerated in Indian infants.

Safety and reactogenicity of a low dose diphtheria tetanus acellular pertussis vaccine (Boostrix) in pre-school Indian children

OBJECTIVE

To evaluate the safety and reactogenicity of a reduced-antigen-content combined Diphtheria Tetanus Acellular Pertussis (dTpa) vaccine in Indian preschool children.

METHODS

GlaxoSmithKline Biologicals combination dTpa vaccine was administered as a single booster dose to 347 children aged 46 years in seven centers across India. All children were subsequently followed up for two weeks for safety and reactogenicity assessment.

RESULTS

A total of 345 subjects completed the study and two subjects were lost to follow-up. One serious adverse event (head injury) unrelated to vaccination was reported. Otherwise, all subjects were in good health throughout the study period. Three subjects (0.9%) reported transient general symptoms (such as irritability and drowsiness), which prevented normal activity. Pain at injection site, swelling and redness was reported in 31.1%, 18.2% and 8.9% subjects respectively. Five subjects (1.4%) reported severe pain preventing normal movement. This resolved within 48 hours in all cases. There were no other severe local reactions including large injection site reactions.

CONCLUSION

The reduced antigen content combined dTpa vaccine is safe and well tolerated in Indian pre-school children.

Assessment of nine candidate DTP-vaccines with reduced amount of antigen and/or without adjuvant as a fourth (booster-) dose in the second year of life

BACKGROUND

The incidence of local reactions to diphtheria-, tetanus and acellular pertussis (DTaP-) vaccines in infants and toddlers increases with each subsequent dose, and entire thigh swellings (ETS) have been reported. Lowering the amount of antigen or of adjuvant may decrease the reactogenicity of DTaP while maintaining a protective immune response.

OBJECTIVES

Following priming with three doses of a DTaP vaccine during infancy, the safety, reactogenicity and immunogenicity of nine different candidate DTaP-vaccines with reduced amounts of antigen and/or adjuvant given as fourth (booster) dose were evaluated.

METHODS

Study participants were healthy infants aged 15-27 months at the time of booster vaccination. Each participant had received three doses of a DTaP vaccine (Infanrixtrade mark, GlaxoSmithKline, Rixensart, Belgium; "reference DTaP") at age 3, 4, and 5 months as part of a previous clinical trial. More than 20,000 children were eligible for participation in the current study protocol at the time. In a first phase at a University hospital-based vaccination study center, nine sequential cohorts of 63-119 study subjects received one of nine different candidate vaccines. Patients and study personal were blinded with regard to which vaccine was currently in use. Reactogenicity was solicited from parents using diary cards. Blood was drawn prior to and 4 weeks after vaccination and immediately centrifuged. The serum was stored at -20 degrees C until serology was performed by ELISA tests. As soon as the first candidate vaccine with adequate reactogenicity and immunogenicity profile was identified in the first study phase, a second study phase was initiated in parallel, to evaluate the safety and reactogenicity of the respective candidate vaccine in private practices in large cohorts (1613-2095 study subjects per group).

RESULTS

In the first study phase, DTaP with no aluminum induced the highest frequency of ETS and fever. All other candidate vaccines caused lower rates of local and general reactions than the reference DTaP. As a general rule, vaccines with less antigen induced fewer reactions, although there was no strict dose-response effect and the difference, e.g. between a one-tenth and a one-fifth DTaP dose (DTaP 1/5; DTaP 1/10) was not clinically relevant. Separate injections of Td and aP caused fewer general reactions than the respective TdaP combination and local reactions were higher at the aP than at the Td injection site. Again, as a general rule, reduced amounts of antigen induced lower antibody concentrations, although all vaccines induced "protective" anti-tetanus and anti-diphtheria antibody responses. A total of 92-100% of children showed seroresponses to pertussis antigens even when vaccinated with reduced amounts of the respective pertussis antigen. Elimination of aluminum from DTaP vaccine induced higher anti-tetanus-antibody concentrations and so did a reduction of the amount of diphtheria antigen. Additional examples for antigen interaction were increased antibody concentrations, observed with injection of Td and aP into different limbs. In the second study phase, all three vaccines evaluated (one with a reduced amount of diphtheria antigen, TdaP; one with reduced amounts of all antigens, tdap; and one with a fifth dose of the reference vaccine (DTaP 1/5)) were safe and had an acceptable reactogenicity profile in a total of 4871 study subjects.

CONCLUSIONS

Local reactions due to DTaP booster doses in the second year of life can be reduced by reducing the amount of antigen in the respective vaccine while an adequate immunogenicity is maintained. Aluminum-free vaccines induced ETS and fever most commonly. Any changes in vaccine composition should lead to a full evaluation of the new product.

A short report on highlights of worldwide development of RIX4414: A Singaporean experience

In Singapore, we conducted a phase II randomized, double-blind, placebo-controlled dose ranging study using an attenuated human rotavirus vaccine, RIX4414. Altogether, 2464 healthy infants were recruited. Two oral doses of vaccine at 104.7, 105.2 or 106.1 ffu or placebo were administered with routine immunizations at 3 and 4 months of age. Seroconversion and 'vaccine take' in the vaccine groups 1-month post dose 2 varied from 76 to 91% and 98 to 100% respectively. Vaccine was well tolerated and did not interfere with response of concomitantly administered vaccines.

Immunogenicity and reactogenicity of a reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine as a single-dose booster in Singaporean adults

INTRODUCTION

Older children and adults, susceptible to pertussis because of waning immunity, may serve as a reservoir of infection, leading to severe disease among young unvaccinated infants. Booster diphtheria-tetanus-acellular pertussis (dTpa) vaccination in older age groups is rare in Singapore, one reason being the increase in reactogenicity with each successive dose. The aim of this study was to assess the immunogenicity, safety and reactogenicity of a reduced antigen, combined dTpa vaccine as a single booster dose in healthy adults aged 18 years or older.

METHODS

A total of 150 healthy adults, 18 to 60 years of age, received a single dose of GlaxoSmithKline Biologicals' dTpa vaccine with reduced content for diphtheria and pertussis, with measurement of pre- and post-vaccination antibody titres.

RESULTS

Prior to vaccination, 71.6 percent and 92.6 percent of the subjects had anti-diphtheria and anti-tetanus antibody levels greater than or equal to 0.1 IU/mL, respectively. 46.7 percent, 98.5 percent and 44.4 percent of subjects were seropositive for pertussis toxin (PT), filamentous haemagglutinin (FHA) and pertactin (PRN) antibodies, respectively. One month after vaccination, there was an increase in geometric mean titres from pre-vaccination to post-vaccination blood samples for anti-diphtheria (greater than seven-fold), anti-tetanus (greater than five-fold), anti-PT (greater than 11-fold), anti- FHA (greater than 25-fold) and anti-PRN (greater than 31-fold) antibodies. Solicited grade three local symptoms (pain, redness and swelling) were reported in 14.1 percent, 8.1 percent and 10.4 percent of subjects, respectively. No serious adverse events were reported.

CONCLUSION

In summary, the dTpa vaccine is immunogenic, safe and well-tolerated in Singaporean adults.

A Rotavirus Vaccine for Infants: The Asian Experience

Introduction: Severe rotavirus gastroenteritis in children causes significant morbidity world- wide and substantial deaths in developing countries. Hence, a live attenuated vaccine Rotarix™ was developed with human strain RIX4414 of G1P1A P[8] specificity. RIX4414 trials in infants have begun in developed and developing countries worldwide. An overview of RIX4414 in developed and developing countries and prospects with this vaccine in Asia are presented. Methods: Completed RIX4414 trials have been reviewed. Results: Two oral doses of RIX4414 were well tolerated with a reactogenicity profile similar to placebo. RIX4414 was also highly immunogenic, e.g., in a dose-ranging study conducted in Singapore, 98.8% to100% of infants had a vaccine take after 2 doses. RIX4414 did not affect the immune response of simultaneously administered routine infant vaccines. RIX4414 significantly reduced severe rotavirus gastroen- teritis in settings where multiple serotypes including the emerging G9 type co-circulated. Conclusion: These encouraging results warrant further evaluation of the vaccine worldwide and especially in developing countries with the highest need. Therefore, evaluation of the Rotarix™ vaccine is continuing in large phase III trials in Asia and worldwide. Key words: Asia, Attenuated, Developing countries, Gastroenteritis, RIX4414

A rotavirus vaccine for infants: the Asian experience

INTRODUCTION

Severe rotavirus gastroenteritis in children causes significant morbidity worldwide and substantial deaths in developing countries. Hence, a live attenuated vaccine Rotarix was developed with human strain RIX4414 of G1P1A P[8] specificity. RIX4414 trials in infants have begun in developed and developing countries worldwide. An overview of RIX4414 in developed and developing countries and prospects with this vaccine in Asia are presented.

METHODS

Completed RIX4414 trials have been reviewed.

RESULTS

Two oral doses of RIX4414 were well tolerated with a reactogenicity profile similar to placebo. RIX4414 was also highly immunogenic, e.g., in a dose-ranging study conducted in Singapore, 98.8% to 100% of infants had a vaccine take after 2 doses. RIX4414 did not affect the immune response of simultaneously administered routine infant vaccines. RIX4414 significantly reduced severe rotavirus gastroenteritis in settings where multiple serotypes including the emerging G9 type co-circulated.

CONCLUSION

These encouraging results warrant further evaluation of the vaccine worldwide and especially in developing countries with the highest need. Therefore, evaluation of the Rotarix vaccine is continuing in large phase III trials in Asia and worldwide.

Immunogenicity and reactogenicity of two regimens of diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio and Haemophilus influenzae type b vaccines administered to infants primed at birth with hepatitis B vaccine

An open, randomized study evaluated the immune response and safety of two different regimens of diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type b (DTPa-HBV-IPV-Hib) immunization in infants primed at birth with hepatitis B vaccine. One-half of the 150 healthy, full-term infants received a DTPa HBV-IPV-Hib vaccine at 1 1/2, 3 and 5 months of age; the other received a DTPa-IPV-Hib vaccine at 1 1/2, 3 and 5 months of age with separate HBV vaccine at 1 and 5 months of age. Immune response was similar following the two regimens with 100% of the vaccinees seroprotected for HBV, diphtheria, tetanus, Hib and poliovirus types 2 and 3 diseases after the full vaccination course. One vaccinee in the DTPa HBV-HPV- Hib group failed to respond to the poliovirus type 1 antigen. Response to the three pertussis antigens ranged from 92-97% in the DTPa-IPV-Hib plus separate HBV group and 100% in the DTPa HBV-IPV-Hib group. The most frequently reported post-vaccination symptoms were irritability in the DTPa-IPV-Hib plus separate HBV group (49% of vaccinees) and fever, defined as axillary temperature > or =37.5 degrees C, in the DTPa HBV- IPV-Hib group (50% of vaccinees).

Concomitant administration of varicella vaccine with combined measles, mumps, and rubella vaccine in healthy children aged 12 to 24 months of age

The reactogenicity and immunogenicity of three combined measles, mumps and rubella (MMR) vaccines and one administered with a varicella vaccine was studied in infants. The vaccines were Priorix (designated MeMuRu, Group 1), M-M-R II (Group 2), Triviraten (Group 3) and Priorix + a varicella vaccine, Varilrix (Group 4). Fever was greater in Group 2 (61.3%) compared to Group 1 (48.5%; p = 0.033) or Group 3 (37.1%; p = 0.009). Rash with fever was reported in Group 2 (4.8%) and Group 4 (3.3%), but not for Group 1. Anti-measles, -mumps and -rubella seroconversion was similar for Group 1 (96.1%, 96.1% and 100%, respectively), Group 4 (98% for all three), and Group 2 (91.5%, 93.6% and 97.9%) 60 days post-vaccination. GMTs for measles (3,053.7-3,412.2 mIU/ml), mumps (1,001.5-1,158.8 U/ml) and rubella (68.7-89.1 IU/ml) were similar for Groups 1, 2 and 4 at Day 60. Antibody persistence was noted 2 years post-vaccination. The MeMuRu + varicella combination showed no clinically relevant increase in reactogenicity and should facilitate introduction of a varicella vaccine into national immunization schedules.

Reactogenicity and immunogenicity of a varicella vaccine in healthy seronegative and seropositive subjects

The epidemiology of varicella appears to be changing: an unexplained upward age shift in varicella prevalence and a subsequent dramatic rise in morbidity and mortality among adolescents and adults have highlighted the importance of effective varicella mass vaccination programs. This age shift is being seen in temperate regions but is particularly marked in tropical and sub-tropical regions. To assess the need for serological pre-screening in mass vaccination programs, we performed an open study to compare the reactogenicity and immunogenicity of a varicella vaccine in initially seronegative and seropositive subjects to see whether there was an increase in reactogenicity among initially seropositive subjects. Two hundred and forty-six seronegative and seropositive male and female subjects, aged 9 months to 60 years, received a single dose of a live attenuated varicella virus (Oka-strain) vaccine, Varilrix (GlaxoSmithKline Biologicals, Rixensart, Belgium). Subjects were categorized according to antibody status and age group; serum antibodies were measured before and after vaccination (day 42). The study showed that there was no difference in reactogenicity in initially seropositive vaccinees compared with initially seronegative subjects. The varicella vaccine was found to be safe and well tolerated in all age groups. Ninety-eight percent of initially seropositive and 94.8% of initially seronegative subjects reported no clinical signs or symptoms during the 42-day follow-up period. The vaccine was immunogenic in both groups. The seroconversion rate after 6 weeks in initially seronegative subjects was 94.3%. In 53.0% of initially seropositive subjects of all age classes, a 4-fold rise in antibody titer was observed.

Immunogenicity and adverse effects of live attenuated varicella vaccine (Oka-strain) in children with chronic liver disease

Varicella infection may cause significant morbidity and mortality especially in immunocompromised persons. Children with chronic liver disease who undergo liver transplantation and need long term immunosuppressive therapy are at risk to acquire the infection. Twenty-nine children (aged 1-12 years) with chronic liver disease were enrolled to receive one dose of live attenuated varicella vaccine (Oka-strain). During the 16-week follow-up period, no vaccine-related serious adverse events were reported. Seroconversion rates at 8 weeks post vaccination were 100%. Geometric mean titer (GMT) values and seropositive rates at 16 weeks tended to relate to the clinical severity of liver disease. This study demonstrates that varicella vaccine is safe and Immunogenic in children with chronic liver disease.

Higher anti-hepatitis B response with combined DTPw-HBV vaccine compared with separate administration in healthy infants at 3, 4 and 5 months of age in Slovakia

To help achieve universal infant immunisation against hepatitis B, the World Health Organisation has recommended the development of a combined diphtheria, tetanus and pertussis (DTP) and hepatitis B vaccine (HBV). The advantages come from the fact that DTP coverage is estimated to be over 80% worldwide and a combined DTP-HB vaccine would increase the coverage of HBV. This study was conducted to compare the immunogenicity and reactogenicity of a combined DTP-HB vaccine with separate, concomitant administration of DTP and HBV vaccines. One hundred and twenty infants were randomised in a 1:1 ratio to one of the two vaccination regimens, given as three injections at approximately 3, 4 and 5 months of age. The only difference in immunogenicity between the two regimens was a higher antibody response to hepatitis B in the group given the combined vaccine, possibly as a result of the adjuvant effect of the whole cell pertussis component of the DTP vaccine. Both vaccine regimens were well tolerated.

Effect of climatic factors and population density on varicella zoster virus epidemiology within a tropical country

Blood samples were collected from healthy subjects, aged 9 months-29 years in urban and rural communities from 4 distinct regions in Thailand, to determine the seroprevalence rate of varicella-zoster virus (VZV) antibody and its relationship with demographic, climatic, and socioeconomic factors. The overall seroprevalence rate was 52.8% and increased from 15.5% in the 9-month to 4-year-old group to 75.9% in the 20-29 year-olds. The age-adjusted seroprevalence was significantly higher in the cooler than in the warmer regions. In the warmer regions only, the age-specific seroprevalence was significantly higher in the urban population than in the rural population. In Thailand, climate is the main determinant of VZV seroprevalence. The delayed onset of natural immunity is more marked in warmer climate areas. Population density is a secondary determinant; in the warmer areas, the pattern of adolescent and adult susceptibility was greater in rural than in urban areas.

Age related seroprevalence of antibodies to varicella in India

OBJECTIVE

To determine the age related prevalence of Varicella Zoster Virus (VZV) antibodies in India.

SETTING

This was a cross sectional multicentric study performed in 4 major cities of India: Calcutta (outpatients), Mumbai (outpatients), Lucknow (walk-in patients to a diagnostic laboratory, orphanage and factory workers) and Bangalore (outpatients and walk-in patients to a diagnostic laboratory).

METHODS

A total of 1609 volunteers from birth to 40 years of age were included into the study. IgG antibodies against VZV were determined using commercial kits (ELISA-Enzygnost).

RESULTS

Overall seroprevalence of anti VZV antibodies was 68. 22percnt. The age related seroprevalence rate of anti VZV antibodies was 29percnt in the age group of 1-5 years, 51.1percnt in 5-10 years, 71.7percnt in 11-15 years, 79.8percnt in 16-20 years, 88.1percnt in 21-30 years and 91.1percnt in 31-40 years.

CONCLUSION

A significant proportion of adolescents and adults are susceptible to varicella in India, as in other tropical countries

Seroprevalence of hepatitis A virus and varicella zoster antibodies in a Javanese community (Yogyakarta, Indonesia)

Hepatitis A virus (HAV) cause an acute inflammation of the liver. Varicella-zoster virus (VZV) cause chickenpox (varicella) and herpes zoster. Effective vaccines against hepatitis A and varicella are available for children, adolescents and adults. In order to implement an appropriate vaccination policy, a baseline to assess the potential benefits and sections of the population who would benefit most are required. We investigated seroprevalence of hepatitis A virus and varicella zoster antibodies in a Javanese community. A total of 1,103 subjects were studied. The 600 subjects aged 4 to 9 years were sampled between 23 October and 2 November, 1995. The other subjects were sampled between 12 October and 1 November, 1996. The overall prevalence of anti-HAV in cohort was 28.7%. Anti-HAV seroprevalence rates were below 30% until the age of 15 and below 40% until the age of 25. The anti-varicella seroprevalence showed only in two thirds of seropositive population at the age of 15. The results of the study have implications for vaccination strategies for both hepatitis A and varicella zoster.

Does the concurrent administration of an inactivated hepatitis A vaccine influence the immune response to other travelers vaccines?

BACKGROUND

Travelers seeking protection from hepatitis A also often need protection against other infections, prevalent at their destinations.

METHODS

A total of 396 volunteers received not only a hepatitis A vaccine but also either a vaccine against polio, hepatitis B, diphtheria, tetanus, yellow fever, Japanese encephalitis, typhoid fever or rabies according to their individual needs. We investigated the potential influence of the hepatitis A vaccination on the immune response to the other travelers vaccines that were administered concurrently.

RESULTS

With seroprotection rates of 100% for yellow fever, Japanese encephalitis and rabies immunization and tetanus boosters our data demonstrate that the concurrent administration of hepatitis A vaccine does not compromise the immune response of these vaccines. Also for oral typhoid, hepatitis B and diphtheria vaccination we did not detect a negative influence of concurrent hepatitis A vaccine administration as compared with respective vaccinations when given alone. Prior to vaccination, more than one third of our subjects lacked protective antibody levels against diphtheria and only 44% of initially seronegative travelers seroconverted to an anti-diphtheria titer > or = 0.01 mIU/mL, supporting a need for an additional dose. Furthermore, only two thirds of the vaccinees tested prior to vaccination were protected against polio type 3, and the seroconversion rate following the administration of oral polio vaccine, was lower for viral type 3 (80%), as has been previously demonstrated in settings without concurrent other vaccinations.

CONCLUSION

No negative effect of concurrent travelers vaccinations on the immune response of a hepatitis A vaccine has been detected in a previous report, and, likewise our data suggest no impairment of the antibody response of these travelers vaccines by the concurrent administration of the hepatitis A vaccine.

A randomized comparative trial in order to assess the reactogenicity and immunogenicity of a new measles mumps rubella (MMR) vaccine when given as a first dose at 12-24 months of age

An open, randomized multi-center trial, involving 700 infants, was conducted in order to compare a new measles mumps rubella (MMR) vaccine, SB MMR (containing a Jeryl Lynn derived mumps strain RIT 4385) with a widely used vaccine, Merck MMR, when given to children between 12-24 months. Infants were divided between 2 groups; group 1 received SB MMR while group 2 received Merck MMR. Solicited local and general symptoms were recorded using diary cards and antibody levels were measured using ELISA assays. There was a significantly lower incidence of redness (p < 0.001) and swelling (p = 0.03) observed in group 1 compared with group 2. The incidence of all other solicited local and general symptoms were comparable between groups. In initially seronegative subjects equivalent seroconversion rates and post-vaccination GMTs were observed between groups. In conclusion, these results demonstrate that SB MMR is safe and well tolerated when given to children at this age range, and has an equivalent immunogenic profile compared to the widely used Merck MMR vaccine.

The new DTPw-HBV-Hib combination vaccine can be used at the who schedule with a monovalent dose of hepatitis B vaccine at birth

An open, randomized, clinical trial was conducted in order to assess the reactogenicity and immunogenicity of DTPw-HBV and Haemophilus influenzae type b (Hib) vaccines when given either as a mixed administration or as separate concomitant injections using the WHO schedule at 6, 10 and 14 weeks of age, following a dose of HBV at birth. There were no clinically relevant differences in the immune response to any component between the mixed and separate administrations. In fact the anti-tetanus GMTs were significantly higher (p=0.002) in mixed administration (3.9 IU/ml) compared with the separate administration (1.9 IU/ml). However although all subjects achieved anti-PRP titers > or = 0.15 microg/ml, higher anti-PRP GMTs were seen in the group receiving the separate administration. Importantly, the addition of Hib did not adversely alter the reactogenicity profile of DTPw-HBV. This report which demonstrates that this novel combination can be used in WHO recommended schedule.

Factors influencing the spread of pertussis in households

The objective of this study was to compare the spread of pertussis in children and adults being secondary contacts after household exposure. The study was nested in an efficacy trial of an acellular pertussis vaccine. The spread of the disease was also monitored with respect to gender and antibiotic therapy. A total of 453 index cases, of which 133 were monitored for adult disease, fulfilled the WHO definition of pertussis. They had contacts to 173 unvaccinated children aged 6-47 months, and a total of 101 adults with pertussis were followed. Detection of the bacteria, or a significant increase of specific antibodies confirmed the diagnosis. Secondary spread of the disease was assumed, when a household member coughed for 7 days or more and had laboratory evidence for pertussis. Crude attack rates (AR) were 69% in children and 31% in adults (P < 0.05). AR in children were independent of gender but more women than men (P=0.02) were affected in those households where the index case was a child. Erythromycin treatment of the index case reduced the AR in exposed toddlers from 80% to 57% (P=0.06), and in exposed adults from 40% to 21% (P=0.2). Erythromycin therapy in contacts did not alter the clinical course of the disease significantly.

CONCLUSIONS

In a household study of pertussis, 69% of children and 31% of adults (more women than men) contracted the disease. Erythromycin reduced the number of infections in household contacts, but did not alter the clinical course in those who contracted pertussis.

Immunogenicity and reactogenicity of a Haemophilus influenzae type b tetanus conjugate vaccine when administered separately or mixed with concomitant diphtheria-tetanus-toxoid and acellular pertussis vaccine for primary and for booster immunizations

With an increasing number of new vaccines available for routine childhood immunization, combination vaccines are needed in order to maintain or achieve a high compliance with recommended immunization programmes. In a prospective, randomized, comparative, multi-centre study, 822 healthy infants were enrolled to receive three doses of either a candidate or a commercially available Haemophilus influenzae type b (Hib) vaccine concomitantly with diphtheria-, tetanus- acellular pertussis (DTaP) vaccine. Study subjects were randomly allocated to one of the following groups: (1) separate, or (2) mixed injection of DTaP and candidate Hib vaccine, or (3) separate injection of DTaP and commercial Hib vaccine. One year later the first 189 study subjects received either separate or mixed injections of the same Hib and DTaP vaccines as booster doses. Evaluation of reactogenicity was based on diary cards completed by parents. Immunogenicity was documented by measuring IgG antibody concentrations in serum samples taken before and 4 weeks after primary and booster vaccination. No serious adverse events occurred and most local and systemic reactions were mild to moderate. Booster doses were more reactogenic than primary doses with all groups. Antibody concentrations against pertussis antigens were similar to those seen with DTaP alone. All but one subject had protective antibody concentrations against diphtheria and tetanus. Primary immune response to the Hib vaccine was significantly lower in the group receiving the mixed Hib-DTaP vaccine, however, > or = 95% of vaccinees had anti-Hib antibody concentrations > or = 0.15 microg/ml and there was a marked booster response (> 100-fold) in all groups.

CONCLUSIONS

Mixing DTaP and Hib vaccines for primary immunization caused a decrease in anti-Hib antibody response, although after primary immunization as after booster doses, all subjects showed antibody concentrations considered to be protective for invasive Hib disease. Mixing of the vaccines did not result in increased reactogenicity.

Safety and efficacy of acellular pertussis vaccines: the Mainz study and other recent studies

Following concerns about the safety and reactogenicity profile of diphtheria, tetanus and whole cell pertussis vaccines (DTwP), new and less reactogenic alternatives were developed over the last two decades. The new diphtheria, tetanus and acellular pertussis vaccines (DTaP) no longer consist of the whole bacterial cell but of either extracts or of a few highly purified components. While it soon became clear that DTaP vaccines are significantly less reactogenic than DTwP vaccines, their efficacy was disputed and remained unproven. First studies and epidemiological data from Japan suggested vaccine efficacy rates (VE) of about 80%; however, the first blinded clinical trial from Sweden documented a much lower VE. Worldwide, seven large DTaP efficacy trials have recently been completed. Our own efforts included a large safety trial with 22505 vaccinees and, nested in this setting, a prospective household contact study. Typical WHO-defined pertussis developed in 7 of 112 DTaP vaccinated children following household exposure as compared to 96 cases in 173 children not vaccinated against pertussis. Thus, vaccine efficacy was calculated to be 88.7% (95% CI 76.6 to 94.6). The median duration of spasmodic cough in the few children vaccinated with DTaP who did start coughing was 17 days as compared to 35 days in unvaccinated children. No waning of protection was observed. None of the confounding variables analyzed influenced study results in favour of DTaP. Following administration of more than 67000 DTaP doses, 153 serious adverse events were reported. Eight events were considered possibly related and five were considered related to the study vaccine. According to additional study results from the other trials it can be concluded that DTaP vaccines, like DTwP vaccines, are safe and effective. The choice between DTwP and DTaP should be based on acceptance of the reactogenicity profile, coverage rates achieved, costs and other factors in each individual country.

Reactogenicity and immunogenicity of a booster dose of a combined diphtheria, tetanus, and tricomponent acellular pertussis vaccine at fourteen to twenty-eight months of age

OBJECTIVES

The primary objective was to assess the nature and incidence of adverse events after a fourth dose of a tricomponent acellular pertussis-diphtheriatetanus vaccine given in the second year of life after primary vaccination with the same vaccine at 3, 4, and 5 months of age. A secondary objective was to analyze the immunogeniecity of the booster vaccination.

DESIGN

Of the 5361 children enrolled (aged 14 to 28 months), adverse reactions were specifically solicited from the first 1863 enrollees for the first 4 days after vaccination and then were unsolicited for the remainder of the 4 weeks of follow-up (group 1). In the next 3498 subjects, safety and reactogenicify were entirely unsolicited for this 4-week period (group 2). Immunogenicity was analyzed by means of prebooster and postbooster serum antibody titers for all vaccine components in a random subgroup of 197 children from group 1.

RESULTS

Soliciting symptoms elicited reports of at least one symptom in 1314 of 1809 children in group 1 (72.6%), including 993 (54.9%) with local and 885 (48.9%) with general symptoms during the first 4 days after vaccination. When symptoms were gathered in an unsolicited fashion, only 580 of 3498 children in group 2 (16.6%) had a reported symptom during this time, consisting of 344 (9.8%) local and 319 (9.1%) general symptoms, respectively. An unsolicited symptom, areactive edematous swelling of the whole thigh, occurred in 62 children (1.1%), with 45 and 17 reports in groups 1 and 2, respectively. The vast majority of all reported symptoms were mild to moderate, and all children recovered without sequelae. Fourteen serious adverse events were reported, but none was considered to be related to the vaccination. Immunogenicity analysis showed a vaccine response to pertussis toxin in 99.5% of subjects, to filamentous hemagglutinin in 98.5%, and to pertactin (69 kd outer membrane protein) in 99%. All subjects had postvaccination antibody titers of 0.1 IU/ml or greater against diphtheria and tetanus toxoids.

Booster immunization of low- and non-responders after a standard three dose hepatitis B vaccine schedule--results of a post-marketing surveillance

Seventy-nine low-responders and 83 non-responders after a previous three-dose hepatitis B (HB) vaccine course at 0.1, and 6 months were enrolled to receive additional 20 micrograms recombinant HB vaccine doses every 2 months until all had anti-HBs levels > or = 100 mIU ml-1. After the first booster, 65.4% had anti-HBs levels > or = 100 mIU ml-1, 17.9% were low-responders (10-99 mIU ml-1), and 16.7% remained non-responders (< 10 mIU ml-1). All complying non-responders developed anti-HBs levels > or = 100 mIU ml-1 after the third booster at the latest, whereas all low-responders reached this level after the second booster. Although body mass index affected the response to the first hepatitis B booster, when full compliance to regular revaccination was ensured, all non- and low-responders eventually reached sufficient anti-HBs levels.

Long-term persistence of anti-HAV antibodies following active immunization with hepatitis A vaccine

Seventy-one anti-hepatitis A virus (HAV) negative volunteers were immunized against hepatitis A. An inactivated hepatitis A vaccine (HAVRIX, SmithKline Beecham), derived from tissue cell cultures, at single doses of 720 ELISA units was used following a schedule of vaccinations at month 0.1 and 6. The vaccines were tested for the presence of HAV antibodies 1 month after each vaccination and then after 2, 3, 4 and 5 years. The annual decrease of anti-HAV titres was 25%. Five years after vaccination a protective antibody titre, varying between 20 and 5200 mIU ml-1, could be demonstrated in all 47 retested volunteers with a geometric mean titre (GMT) of 442 mIU ml-1. Levels of anti-HAV-antibodies following active immunization were significantly higher in female volunteers. This could be consistently demonstrated throughout the observation period. Based on these data the antibody persistence was calculated over time. GMTs at protective levels higher than 20 mIU ml-1 can be expected to persist for at least 15 years.

Factors influencing the analysis of secondary prevention of pertussis

The aim of this study was to evaluate factors that influenced the spread of pertussis in secondary contacts after household exposure. The data were acquired during a prospective household-contact study into the efficacy of an acellular vaccine. The spread of the disease was monitored with respect to various case definitions of pertussis, socio-economic factors, household composition, and antibiotic therapy. A total of 453 index cases had contact with 173 unvaccinated children aged from 6 to 47 months. Depending on the clinical case definition, the attack rates (AR) in children with a laboratory-confirmed Bordetella infection increased from 55% for the WHO definition to 69%, when a less stringent definition was used. AR in children were independent of age and gender. The social status of the family had no significant influence on the AR in children. Erythromycin treatment of the index case reduced the AR from 64% to 51% (p = 0.08). These factors should be taken into consideration when studies into the secondary prevention of pertussis by acellular vaccines are initiated.

Acellular pertussis vaccines: the rationale for an efficacy trial in Germany

After concern about the safety of diphtheria-tetanus toxoid-whole cell pertussis vaccines (DTPw), the recommendation to vaccinate children with DTPw was withdrawn in 1974 in the former West Germany. This led pertussis cases to increase to an estimated 100,000 annually. Despite renewal of the vaccination recommendation in 1991, vaccine use remained low. The German health care structure assures regular contact between most children and pediatricians. This enabled the conduct of a large efficacy trial with a diphtheria-tetanus toxoid-acellular pertussis (DTPa) vaccine. Because a placebo-controlled trial was not ethically possible, a prospective household contact study with a blinded clinical follow-up was done. Possible study participants were screened by their pediatrician, who also initiated diagnostic procedures. Clinical follow-up was done by another locally based but independent and blinded physician. Vaccine efficacy was calculated to be 89% (95% confidence interval, 76.6%-94.6%). None of the identified confounding factors biased results in favor of the DTPa vaccine.

Immunogenicity of a recombinant hepatitis B vaccine in adults

OBJECTIVES

To evaluate the immunogenicity and reactogenicity of a recombinant hepatitis B vaccine in health care staff under routine use and unselected conditions and to investigate factors that influence the response to vaccination.

METHODS

This prospective postmarketing surveillance study was performed in unselected health care staff and their relatives (age range, 12-60 years) at 58 hospitals. Overall, 880 subjects were administered a 20-microgram dose of a vaccine at 0, 1, and 6 months according to the prescribing information and under routine hospital practice, and they were tested for antibody to hepatitis B surface antigen after the third dose at the hospitals routine laboratory. The principal outcome measures were antibody to hepatitis B surface antigen titers that were expressed as the seroprotection rate (SPR) (SPR [given as a percentage], > or = 10 mlU/ mL), spontaneously reported adverse events, and geometric mean titers (in milli-international units per milliliter).

RESULTS

The compliance to the 3-dose schedule under routine hospital practice was 98.1%. The immune response was good in all age groups, and the overall SPR was 97.8% at 1 month after the third dose in field conditions with unselected health care workers. The SPR in vaccinees (age range, 40-59 years) was close to 95%. Age (P < .001), smoking (> or = 10 cigarettes per day) (P < .001), Broca index (> 110%) (P < .001), antibody to hepatitis B surface antigen testing (> 8 weeks after the last dose) (P = .03), chronic underlying disease (P = .04), and male gender (P = .04) were factors associated with lower geometric mean titers in routine vaccine use. No serious adverse events were reported.

CONCLUSION

The large immune response that was elicited by this hepatitis B vaccine in adults under daily routine field conditions reflected reality, with a high SPR also found in elderly and other persons with risk factors associated with a lower immune response.

Immunogenicity and reactogenicity of a combined hepatitis A/B candidate vaccine: first results

We evaluated immunogenicity and reactogenicity of an inactivated, combined hepatitis A/B candidate vaccine in 50 seronegative volunteers. Each volunteer received a total of three doses of vaccine (720 EIU HAV and 20 micrograms HBs antigen) according to a 0, 1 and 6 month vaccination schedule. One month after the first injection, the seroconversion rate was 90% (45/50) for anti-HAV and 28% (14/50) for anti-HBs, respectively. After the booster dose, at month 7, the seroconversion rate was as high as 100% (49/49) for anti-HAV and 94% (46/49) for anti-HBs. The geometric mean titres increased with each dose of vaccine administered. Mild, and mostly local side effects were reported in 54% of the volunteers after the first injection and in less than 10% after the third injection. Our results show that this inactivated, candidate hepatitis A/B vaccine is highly immunogenic and well-tolerated.

Immunogenicity of an inactivated hepatitis A vaccine administered according to two different schedules and the interference of other "travellers" vaccines with the immune response

A total of 2036 persons consulting vaccination centers in Germany were vaccinated with an inactivated hepatitis A vaccine (containing 720 ELISA units of antigen) either according to the standard schedule (two vaccinations given 4 weeks apart) or to an abbreviated schedule (two vaccinations given 2 weeks apart) in a controlled clinical study. The abbreviated schedule induced a similar rate of seroconversion and geometric mean antibody titre as compared to the standard schedule. The incidence of reactions reported after vaccination was similar in both groups. When other "travellers" vaccines were given simultaneously neither the immunogenicity nor the reactogenicity of the hepatitis A vaccine were influenced. These findings have considerable practical importance in the prevention of hepatitis A in travellers.

Efficacy of acellular pertussis vaccine in early childhood after household exposure

OBJECTIVE

To evaluate the efficacy of a three-dose primary vaccination with a diphtheria-tetanus tricomponent acellular pertussis vaccine against "typical" pertussis, defined as a spasmodic cough of 21 days or longer with confirmation of Bordetella pertussis infection by culture or serology.

DESIGN

Passive monitoring for suspected first household (index) cases of typical pertussis in six areas in Germany comprising 22,505 children vaccinated with study vaccine at 3, 4, and 5 months of age. Blinded, prospective follow-up of household contacts of index cases for incidence and progression of pertussis.

SETTING

Six areas in Germany with a high incidence of pertussis.

SUBJECTS

Four hundred fifty-three households with index cases comprising 360 evaluable contacts eligible for analysis of vaccine efficacy.

MAIN OUTCOME MEASURE

Vaccine efficacy from attack rates of pertussis in household contacts classified by vaccination status.

RESULTS

Of the 173 nonvaccinated household contacts, 96 developed typical pertussis, compared with seven of 112 contacts vaccinated with acellular pertussis vaccine. Vaccine efficacy was consequently calculated to be 88.7% (95% confidence interval, 76.6% to 94.6%). Protection did not wane until at least the time recommended for booster vaccination. None of the analyzed potential confounding factors--age, socioeconomic status, erythromycin treatment, household composition, center effect, and selection bias--influenced study results in favor of the vaccine.

CONCLUSIONS

Under conditions of intense household exposure, primary vaccination with acellular vaccine protected against pertussis until at least the time recommended for booster vaccination. The vaccine can be expected to be equally or more effective in settings with lower infectious pressure.

Accelerated Schedule for Hepatitis B Immunization

Background: A considerable number of people remain unprotected against hepatitis B. These people may require immunization at short notice before being exposed to situations or locations where a risk of infection is present. Currently, full active immunization against hepatitis B, when administered according to recommended schedules, takes 2-6 months. This open, randomized multicentric study evaluated the reactogenicity and immunogenicity of a recombinant hepatitis B vaccine in adults when it was administered according to three different rapid vaccination schedules. Methods: Five hundred and twenty four healthy adults (aged 18-59 years) were randomly divided into three groups. Hepatitis B vaccine was given intramuscularly in the deltoid muscle at months 0, 1, and 2 (group A); weeks 0, 14, and 28 (group B); and weeks 0, 7, and 21 (group C). Symptoms were recorded by the subjects on individual diary cards. AntiHBs were measured using radioimmunoassay (Ausab-Abbott); a seroprotective titer was defined as 10 IU/L. Results: At day 28, no significant difference in seroprotection rates (SPRs) i.e., seroconversion >= 10 IU/L,was observed, between groups B (55.6%) and C (65.2%), but both these groups had significantly greater SPRs than group A (15.0%). Although not significant (p=.07), groups B and C also had higher SPRs than group A (78.5% and 76.4% versus 65%) at day 56. One month after completing the three dose schedules, the SPRs were as follows: 89.0% (group A); 78.5% (group B); and 76.4% (group C), increasing to > 94% at month 7 to 8 in all three groups. The SPRs at month 13 were 95.8%, 98.9%, and 98.6%, respectively. Among the three groups, no significant differences were observed from month 2 onwards in either SPRs or geometric mean titers. In groups A, B, and C, 3.7%, 5.0%, and 7.1% of the vaccine injections were associated with local symptoms. Also 8.3%, 6.2%, and 6.3% of subjects exhibited general symptoms following each vaccine dose; all symptoms were transient and resolved spontaneously. Conclusions: This recombinant hepatitis B vaccine administered at weeks 0, 7, 21, or at weeks 0, 14, 28, rapidly elicits high rates of seroprotection, which persist at least until month 12.

Pertussis in adults: frequency of transmission after household exposure

Although pertussis in adults is well documented, opinions differ about incidence of adult disease and about the role of adults as reservoirs of infection. We made use of a prospective household contact study of an acellular pertussis vaccine to collect data about pertussis in adults. All members of families with an index case of pertussis were monitored for respiratory symptoms, and pertussis was confirmed by laboratory tests. In 122 households, 104 children (85%) and 18 adults (15%) were the source of pertussis. These households consisted of 265 adults (aged 19-83 years), in 84 of whom (31%) pertussis was confirmed. Of these 84, 81% had respiratory symptoms for 21 days or more. The spread of pertussis was independent of whether a child (74/104) or an adult (14/18) was the index case. Most adult index cases had no pertussis recall (odds ratio 11.8). The overall attack rate in adult contacts was 0.267 and was independent of the social status and the size of the family and of a pertussis recall, although it differed significantly between women and men (p < 0.05). Erythromycin treatment of the index case reduced the attack rate significantly (p < 0.05). Patients whose first pertussis episode dated back more than 20 years had similar symptoms and attack rates to patients without a recall. We conclude that adults are often involved in the spread of pertussis, and that they can be susceptible to reinfection 20 years after a first pertussis episode.

[Immunogenicity and tolerance of a combined hepatitis A/B vaccine. Preliminary results with a candidate vaccine]

AIM OF STUDY

Active immunization against hepatitis A having been undertaken in Germany since January 1993, a multicentre study was conducted to test, for the first time, immunogenicity of and tolerance to a candidate vaccine against hepatitis A and B.

SUBJECTS AND METHODS

50 healthy volunteers aged 18-40 years, negative for antibodies against hepatitis A (HAV) and B (HBs), received three intramuscular injections of the candidate vaccine (720 EIU of strain HM 175 and 20 micrograms recombinant HBsAg) in a total volume of 1 ml, on day 1 and then, one month and 6 months later.

RESULTS

Four weeks after the first injection the seroprotection rate (percentage of subjects with protective antibody titres) was 90% for HAV and 28% for HBs. The second injection produced seroconversion rates of 98% and 50%, respectively, and after the third one of 100% and 98%. All reported side effects were minor, of short duration and decreased after each injection. After the first injection, effects at the site of injection occurred in 50% of subjects, decreasing to 6% after the third one. The only systemic side effect, headache, occurred in only 4% of subjects and only after the first injection.

CONCLUSION

The test vaccine against hepatitis A and B proved to be highly immunogenic, safe and well tolerated.

Immunogenicity and safety of an inactivated hepatitis A vaccine in anti-HIV positive and negative homosexual men

The immunogenicity, reactogenicity, and safety of an inactivated hepatitis A vaccine were assessed in anti-HIV positive homosexual men. Fourteen anti-HIV positive (group 1) and 20 anti-HIV negative (group 2) men received vaccine (containing 720 ELISA units of hepatitis A antigen per dose) intramuscularly at 0, 1, and 6 months. Twelve unvaccinated anti-HIV positive men (group 3) were included as controls to evaluate disease progression. Seroconversion (anti-hepatitis V virus (HAV) > or = 20 mlU/ml) was higher in group 2 than group 1 at months 2 (100% vs. 73%) and 7 (100% vs. 77%). Group 2 had higher antibody titres than group 1 at months 1 (201 vs. 92 mlU/ml) and 7 (1,687 vs. 636 mlU/ml). The decline in CD4+ cells between months 0 and 7 was similar in groups 1 and 3 (6.4% vs. 16.2%), showing no evidence for harmful effect of the vaccine on the course of HIV infection. This hepatitis A vaccine appears safe, well tolerated, but less immunogenic in HIV positive homosexual men.

Symptoms and complications of pertussis in adults

There is increasing evidence that pertussis occurs frequently in adults, but there is limited information on the clinical course of this disease beyond childhood. A household contact study on the efficacy of an acellular pertussis vaccine was used to study the symptoms of pertussis in adults. Among 257 patients with pertussis identified in 121 families during a two-year period in one study center with a low whole-cell pertussis-vaccine uptake, 79 (30.7%) were adults, aged 19-83 years (mean age: 36 years) with a 1:1.8 male to female ratio. Ninety-one percent of the adults suffered from coughing (mean duration: 54 days), and in 80% this cough lasted > or = 21 days. Whoops were rare (8%), whereas cough followed by vomiting and/or choking (53%) and cough disturbing sleep (52%) were common. This is the first report to describe sweating attacks as symptom of pertussis (14%). Pharyngeal symptoms (37%), influenza-like symptoms (30%), sneezing attacks (22%), hoarseness (18%), sinus pain (16%) and headaches (14%) were also observed. Various complications were seen in 23% of the patients. In order to minimize the spread of the organism, microbiological diagnostics should be vigorously applied to all symptomatic contacts of a patient with pertussis but also to all patients with long lasting cough-irrespective of age.

Therapeutic effects of antivenom supplemented by antithrombin III in rats experimentally envenomated with Russell's viper (Daboia russelli siamensis) venom

The effects of equine antivenom and antithrombin III (AT-III) on the coagulopathy induced by Russell's viper venom (RVV, Daboia russelli siamensis) were investigated in the rat. After taking blood samples from the femoral vein for determination of simple blood clotting time and AT-III activity, all anaesthetized rats received an intramuscular injection of venom (2 micrograms/g). Treatment (antivenom or AT-III or both) was given intravenously through another femoral vein 30 min after venom injection. All untreated rats (n = 7) developed AT-III depletion (< 70%) [mean (S.D.)] 70 (36) min, and incoagulable blood 85 (53) min after venom injection. Supplementation with AT-III (either 0.25 U/g or 0.5 U/g) had no effect on the RVV induced coagulopathy (n = 20). Treatment with antivenom alone (10 micrograms/g) reduced the incidence of abnormal clotting significantly (8/15, 53%) (P = 0.03). When antivenom was given in combination with AT-III (0.5 U/g), abnormal clotting was prevented in all but one animal (1/15, 7%) (P = 0.007). AT-III activity declined progressively in all rats which developed non-clotting blood. These results suggest that coagulopathy in Russell's viper envenoming is associated with activation of coagulation and consumption of AT-III. Antivenom can prevent coagulopathy, but its neutralizing activity is augmented significantly by AT-III supplementation.

Activation of the coagulation cascade in severe falciparum malaria through the intrinsic pathway

The mechanisms involved in the activation of the coagulation cascade in severe falciparum malaria were studied in 22 adult patients (19 male, three female) aged 18-45 (mean +/- SD 31 +/- 11) years. Of these, nine had multiple vital organ dysfunction, and bleeding occurred in four patients, two of whom died. During acute illness the reduction in plasma antithrombin III (AT III) concentrations and elevation in thrombin-AT III complexes were associated with significant reductions in factor XII and prekallikrein activities, and an increase in the C1 inhibitor antigen/activity ratio. Serial plasminogen activity remained within the normal range in all patients while protein C activity was significantly reduced. All patients had markedly elevated plasma polymorphonuclear leucocyte elastase (PMN-elastase) levels with mild depletion of alpha-2 macroglobulin but normal concentrations of alpha-1 antitrypsin. There was no correlation between PMN-elastase concentrations and any of the coagulation parameters or concentrations of proteinase inhibitors. These results suggest that the intrinsic pathway of the clotting cascade is activated in severe malaria. This may cause activation of the complement system and release of bradykinin and PMN-elastase and could contribute to the pathogenesis of severe malaria.

[Active immunization against hepatitis A. Comparison of various immunization schedules]

Three different immunization schedules were compared in 144 young, healthy adults (81 men, 63 women; mean age 28.5 years). They were randomly assigned to one of three groups: group 1, immunization shots on day 0 and day 14 (n = 47), group 2, on day 0 and day 28 (n = 50), and group 3, on day 0, 14 and 28 (n = 47). All participants had a booster shot after one year. The seroconversion rate was 40-46% after first shot, 95-100% after the second one; all were anti-HAV positive after the booster injection. All subjects had specific antibodies in a mean concentration of > 400 IU/l two weeks after the second shot. In almost all subjects antibodies were demonstrable up to the 12th month after the first immunization (> 20 IU/l). Mean antibody concentration during the interval between the second and third immunization after basal immunization on day 0 and 14 or 0 and 28, respectively, was comparable. Three initial immunizations 14 days apart did not achieve much higher anti-HAV levels. The vaccine was equally well tolerated in all three groups. Thus basal immunization shortened to two injections two weeks apart presents a good alternative to the standard scheme of two injections four weeks apart. Three injections two weeks apart bring no demonstrable advantage.

[Halofantrine in the treatment of imported malaria in nonimmune travelers]

The efficacy (criteria: cure rate, time to resolution of fever or absence of parasites) and safety (criteria: clinical side effects, altered laboratory parameters) of halofantrin were investigated in a multi-centre study of 96 non-immune patients (71 men, 25 women, mean age 34.3 [21-62] years) with malaria imported from regions of high resistance into Germany or Switzerland. The initial 63 patients received one-day treatment (three doses of 500 mg halofantrin), while the last 33 patients received an additional course of treatment one week later. Treatment was curative in all patients in the second group, but relapses occurred in five of the 41 patients (12.2%) with falciparum malaria who received one-day therapy. Fever resolved after a mean of 45 hours and parasites were absent after a mean of 66 hours. There were small increases in transaminase values (most probably because of the infection) in five patients, but all became normal again within a few days. Halofantrin is a safe drug and is suitable for both therapy and stand-by therapy of resistant Plasmodium infections. Treatment should be repeated after 7 days.

The efficacy of halofantrine in the treatment of acute malaria in nonimmune travelers

A multicenter prospective trial was performed to investigate the efficacy and the tolerability of halofantrine in nonimmune patients with malaria imported from areas with drug-resistant falciparum parasites (mainly Africa). Forty-five of the 74 subjects were treated with a one-day regimen (3 x 500 mg) of halofantrine, and the other 29 received the same regimen with an additional treatment on day 7. In the second group, a 100% efficacy rate was demonstrated, but in the group receiving the one-day regimen, four recrudescences were observed in patients with falciparum malaria. Only five mild adverse reactions were seen, which disappeared spontaneously after the end of the treatment. We conclude that halofantrine is highly effective in curing malaria in nonimmune subjects. The treatment scheme for such persons should include an additional treatment on day 7 for nonimmune individuals. This drug was well tolerated in our patients, indicating that halofantrine will be useful in the treatment of multidrug-resistant malaria in nonimmune persons.