Serologic responses to ACYW135 polysaccharide meningococcal vaccine in Saudi children under 5 years of age.

An immunization campaign with meningococcal ACYW135 polysaccharide vaccine was conducted in 2003 by the Saudi Arabian Ministry of Health and included a study to evaluate the immune responses in children under 5 years of age in the Al Qassim region of Saudi Arabia. Children who were >/=24 months old were given one dose of tetravalent polysaccharide vaccine, while younger children were given two doses with an interval of 2 to 3 months. Blood samples were collected prevaccination and 1 month after the second dose for children younger than 24 months old and 1 month after the single dose for older children. Serogroup-specific antibody responses were determined by serum bactericidal antibody (SBA) assays and a tetraplex immunoglobulin G (IgG) bead assay. Significant increases in the proportions of individuals who were >/=24 months old with SBA titers of >/=8 were observed pre- to postvaccination for all serogroups. Age-dependent increases in the percentage of individuals with SBA titers of >/=8 1 month postvaccination were observed for each serogroup. Age-dependent increases in postvaccination IgG levels were observed for serogroup A (menA), serogroup W135 (menW), and serogroup Y (menY) but not for serogroup C (menC). Two doses of tetravalent polysaccharide vaccine in individuals who were /=8. A high percentage of subjects who were >/=2 years of age were putatively protected for menA; a similar level was observed for menY for children who were 4 years of age but not for younger children. However, for menC and menW poor levels of putative protection were still evident at 4 years of age.

Serosurvey of hepatitis B surface antigen in pregnant Saudi women.

In 1990, Saudi Arabia began vaccinating all children at school entry against hepatitis B. We evaluated hepatitis B surface antigen (HBsAg) prevalence rate among pregnant Saudi women 12 years later in 5 regions of the country. Using multistage sampling, 2664 pregnant Saudi women were recruited. Blood samples were tested for HBsAg; positive samples were also tested for hepatitis Be antigen (HBeAg). In all 2.44% were positive for HBsAg and 4 (0.15%) were also positive for HBeAg. HBsAg prevalence was highest in Gizan (4.2%) and lowest in Tabuk (1.4%). Positivity for women < or = 20 years of age was 0.5% compared with 2.6% for older women (P = 0.049). The overall HBsAg prevalence rate was lower than previously reported.

Serosurvey of hepatitis B surface antigen in pregnant Saudi women

In 1990, Saudi Arabia began vaccinating all children at school entry against hepatitis B. We evaluated hepatitis B surface antigen [HBsAg] prevalence rate among pregnant Saudi women 12 years later in 5 regions of the country. Using multistage sampling, 2664 pregnant Saudi women were recruited. Blood samples were tested for HBsAg; positive samples were also tested for hepatitis Be antigen [HBeAg]. In all 2.44% were positive for HBsAg and 4 [0.15%] were also positive for HBeAg. HBsAg prevalence was highest in Gizan [4.2%] and lowest in Tabuk [1.4%]. Positivity for women < or = 20 years of age was 0.5% compared with 2.6% for older women [P = 0.049]. The overall HBsAg prevalence rate was lower than previously reported

Effect of gender on reporting of MMR adverse events in Saudi Arabia.

We evaluated the safety of a measles-mumps-rubella (MMR) immunization campaign for Saudi children (age range: 6-13 years) and gender differences in reporting post-MMR adverse events. After vaccinations were administered, we monitored 160 schools for 14 days and 19 hospitals in the 8 cities under study for 10 weeks. Incidence rates were: all MMR adverse events, 26.5/10,000 MMR vaccines (significantly higher in females than males); Urabe strain aseptic meningitis, 1.0/295,000; fever, 40.2/10,000 (females) and 0.9/10,000 (males); and parotitis, 5.4/10,000 (females) and 0.9/10,000 (males). Combined MMR vaccine containing the Urabe mumps strain was safe for children aged 6-13 years. Gender differences regarding reactogenicity were evident and should be considered when designing future studies.

Effect of gender on reporting of MMR adverse events in Saudi Arabia

We evaluated the safety of a measles-mumps-rubella [MMR] immunization campaign for Saudi children [age range: 6-13 years] and gender differences in reporting post-MMR adverse events. After vaccinations were administered, we monitored 160 schools for 14 days and 19 hospitals in the 8 cities under study for 10 weeks. Incidence rates were: all MMR adverse events, 26.5/10,000 MMR vaccines [significantly higher in females than males]; Urabe strain aseptic meningitis, 1.0/295,000; fever, 40.2/10,000 [females] and 0.9/10,000 [males]; and parotitis, 5.4/10,000 [females] and 0.9/10,000 [males]. Combined MMR vaccine containing the Urabe mumps strain was safe for children aged 6-13 years. Gender differences regarding reactogenicity were evident and should be considered when designing future studies

Measles immunization in Saudi Arabia: the need for change.

This paper describes the measles immunization programme in Saudi Arabia and the change from the single-dose schedule with the Schwartz vaccine to the double-dose schedule with the Edmonston-Zagreb vaccine. The recent measles-mumps-rubella school campaign is also described.

Measles immunization in Saudi Arabia: the need for change

This paper describes the measles immunization programme in Saudi Arabia and the change from the single-dose schedule with the Schwartz vaccine to the double-dose schedule with the Edmonston-Zagreb vaccine. The recent measles-mumps-rubella school campaign is also described

Follow-up of Saudi children vaccinated with Haemophilus influenzae type B vaccine.

BACKGROUND: Saudi children vaccinated with a primary series of Hib vaccine (HbOC) at six weeks, three and five months have shown higher antibody titers compared to recent data from the U.S. The aim of this study was to evaluate the persistence of antibodies and to measure the immunogenicity of a booster dose of Haemophilus influenzae type b (Hib) vaccine in Saudi children. PATIENTS AND METHODS: In the first phase of the trial, 210 children were divided into three groups. Group 1 received HbOC, DPT and the WHO formula of oral poliovirus vaccine (OPV); group 2 received HbOC, DPT and the FDA formula of OPV; and group 3 (control) received DPT and the WHO formula of OPV, without HbOC. Haemophilus influenzae geometric mean antibody levels after primary immunization were reported previously. In this study, blood samples were collected at 18 months (before the booster dose) and one month later to measure antibody levels against Haemophilus influenzae polysaccharide. RESULTS: Following the booster doses, there was an increase in the geometric mean titers (GMTs) from 2.57 microg/mL to 39.4 microg/mL in group 1, and from 1.2 microg/mL to 48.9 microg/mL in group 2. In group 3, the GMT remained at 0.3 microg/mL. There was no significant difference in Hib GMTs after the booster dose between children given Hib vaccine with the FDA formula of DPT and OPV and those given the WHO formula. CONCLUSION: Based on the high immunogenicity of the Hib vaccine in Saudi children, a booster dose is not necessary at the initial stages of immunization, and should instead be given to children in the second year of life. This option, however, needs further evaluation and close monitoring.

Determinants of case fatality rates of meningococcal disease during outbreaks in Makkah, Saudi Arabia, 1987-97.

We studied case-fatality rates (CFRs) among cases of meningococcal disease (MCD) admitted to Makkah (Saudi Arabia) hospitals during the period 1988-97. Of 483 cases, 431 (89.2%) were due to strains of serogroup A, 31 (6.4%) to serogroup W135, 16 (3.3%) to serogroup C, and 5 (10%) to serogroup B. Eighty-one patients died (case fatality rate (CFR)) 16.8%, 95% CI 13.5%, 20.4%). The CFR in infections due to serogroup A strains was 14.8%, and for other serogroups it was 32.7% (95% CI 20.3%, 47.1%). The CFR of MCD due to N. meningitidis serogroup A increased steadily with age (P<0.05). Seeking first medical help at a foreign Hajj medical mission and being treated in a non-specialized hospital were associated with a higher case fatality rate.

Seroepidemiology of hepatitis B virus infection in Saudi children 8 years after a mass hepatitis B vaccination programme.

OBJECTIVES: On October 1 1989, a programme was begun in Saudi Arabia in which the HBV vaccine was added as the 'seventh' primary immunogen of the Extended Programme of Immunization (EPI). In 1990, another programme was launched by the Ministry of Health to vaccinate all school children. Eight years after this mass vaccination programme, the efficacy of HBV vaccine was evaluated in a community-based study. METHODS: A community-based study was carried out in Saudi children in urban and rural areas, covering all the regions of Saudi Arabia. After informed consent, blood samples were obtained and tested for HBV markers. RESULTS: Among 4791 vaccinated Saudi children aged 1-12 years, only 15 were found to be HbsAg-positive (0.31%). HbsAg-positivity was 0.16% in children vaccinated at birth compared with 0.7% in those vaccinated at school entry. The overall HbsAg carrier rate dropped from 6.7% in 1989 to 0.3% in 1997 (P<0.00001). Similarly, there was a significant reduction in the prevalence of anti-HBc from 4.2% in 1989 to 0.46% in 1997 (P<0.00001). The overall seroconversion rate to HB vaccine among 4087 Saudi children up to 12 years of age was about 77%. Seroconversion rate in those vaccinated at birth was 77% compared with 71% in those vaccinated at school entry. After 8 years of receiving the third vaccine dose, close to 65% of the children had an anti-HBs titre of more than 10 IU/l compared with about 28% who had an anti-HBs titre of more than 100 IU/l after the same period. CONCLUSION: The result of this study demonstrates the tremendous impact of the mass HB vaccination programme on the seroepidemiology of HBV infection in Saudi Arabia. The ultimate goal of preventing HBV-related chronic liver disease and hepatocellular carcinoma in Saudi Arabia is foreseeable in the near future.

Measles immunization: early two-doses policy experience.

Before the implementation of the two-dose measles immunization policy in Saudi Arabia, 50 per cent of measles cases in children below the age of one year were reported for the age group 6-8 months. In 1991 two doses of measles vaccine, at 6 months and 12 months, the second dose incorporated with MMR, were integrated into the expanded programme of immunization (EPI). Since 1993, vaccination coverage for the second dose has been above 90 per cent. While measles incidence remains stable in infants below 6 months of age, the incidence in children 9-11 months of age dropped by 50 per cent. The greatest impact was seen in the 6-8-month age group where the incidence dropped by more than 75 per cent. Moreover this two-dose strategy resulted in a situation in which 80 per cent of the measles cases were in children above the age of 5 years, mostly those who had not had two doses of measles vaccine. Further control measures should include non-selective vaccination of school children against measles. The two-dose measles vaccination policy is visualized as a necessity if the goal of measles elimination is to be achieved. Routine monthly reports validated by surveys using the WHO standard 30 cluster technique was used for the study.

Evaluation of National Immunization Days in high risk area of Saudi Arabia.

Full text is available as a scanned copy of the original print version.

Immunogenicity study for Tetra and Penta component vaccines in infants.

Full text is available as a scanned copy of the original print version.

Hepatitis A in Saudi Arabia: A comparative sero-epidemiological study.

Full text is available as a scanned copy of the original print version.

Immunogenicity of FDA DTP versus WHO DTP.

BACKGROUND: The aim of this report was to study the immunogenicity of three doses of DTP in six-week-old Saudi infants when given either as World Health Organization (WHO) DTP or Federal Drug Administration (FDA) DTP formula. METHODS: As part of the Haemophilus influenzae type b immunization research protocol, six-week-old infants were randomized into three groups to receive three doses of HbOC and WHO DTP formula, HbOC and FDA DTP formula, or in a control group to receive the usual vaccines without HbOC, at six weeks, three months and five months. Antibody levels for PRP, tetanus, diphtheria and pertussis were measured after the third dose. The results of diphtheria, pertussis and tetanus are presented in this paper. RESULTS: After three doses, no difference was found between anti-PRP when given with either FDA DTP or WHO DTP formula. Also anti-tetanus and anti-diphtheria antibodies were significantly higher in the group vaccinated with HbOC and FDA DTP formula, compared to children vaccinated with WHO DTP formula. No negative interactions with other vaccines were observed after the third dose. Conclusion. Although diphtheria and tetanus antigens in the FDA formula are half the concentration in the WHO formula, they are more antigenic. There is a need for methods of potency assay to be re-evaluated.

Childhood epidemiology of hepatitis A virus in Riyadh, Saudi Arabia.

The prevalence of anti-HAV antibody in children was tested in subjects presenting at clinics in Riyadh, Saudi Arabia. A blood sample was taken to test for the presence of IgG (indicating past infection) and a questionnaire concerning personal and epidemiological data relating to hepatitis A was completed. In total, 592 children aged 6 months to 15 years were suitable for the analysis. There were 179 subjects who were positive for HAV (30.2%). The proportions of subjects positive for HAV varied significantly with age (P=0.001); 32%-49% in the 7-15 age range were positive compared with 13-20% aged 6 and below. There was a significant association between a positive HAV test and social level (P=0.044), with a higher proportion positive in the low social level. Children with jaundice, personal history of jaundice or travel abroad were significantly more likely to be HAV positive (P=0.001, P=0.006, P=0.021, respectively). There was also a significant association with nationality (P=0.022), where the lowest proportion of HAV positive children were Saudi Arabian (28%). Compared to previous studies, there is a significant decrease in the HAV exposure in Saudi children with shift from high to intermediate pattern. National strategy for prevention should be evaluated.

National serosurvey of post vaccination poliovirus antibody in Saudi Arabia.

This is a national seroprevalence study conducted in Saudi Arabai in 1991G to determine postvaccination poliovirus antibody. Two hundred and nine children vaccinated with three oral polio vaccines at three, four, and five months of age were included in the study representing the five main regions in Saudi Arabia. Blood samples were collected at the age of nine months. Cytopathic effect (CPE) neutralization was used to determine the level of polio antibody. A dilution of 1/8th or more was defined as positive. Seventy-nine percent, 88% and 65% of the children were positive for Type 1, Type 2, and Type 3, respetively. Development of a new strategy of polio vaccination is needed.

The potential role of various species of intermediate hosts of Schistosoma haematobium in Saudi Arabia.

The potential role of 3 species of Bulinus in the transmission of Schistosoma haematobium in Saudi Arabia was assessed on the basis of their susceptibility to experimental infection, their geographical distribution and numbers, and the type of habitats in which they were found. B. truncatus, distributed mainly in the mid- and south-western regions, showed extremely low susceptibility to strains of S. haematobium from Yemen, Egypt and Sudan. The same species from one area in the north-west was refractory to a strain of the parasite from Yemen. In contrast, B. wrighti was very susceptible to infection but is found only in a few habitats far from human settlements, thus probably playing little part in the transmission of the disease. As B. beccarii is highly susceptible to the infection and is distributed widely, this snail is probably the main intermediate host of schistosomiasis in Saudi Arabia.