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Discussion of Immunization Practices Advisory Committee/American Academy of Pediatrics recommendations for universal infant hepatitis B vaccination.

The Committee on Infectious Diseases of the American Academy of Pediatrics and the Advisory Committee on Immunization Practices of the United States Public Health Service have revised the recommendations for hepatitis B control to include universal immunization of infants. Previous selective strategies targeting high risk groups for immunization have failed to prevent the significant morbidity and mortality associated with hepatitis B virus infection. The committees considered several alternative policy options before selecting universal immunization of infants as the most effective strategy for preventing the disease and its sequelae in the United States. More than 30 other countries have also adopted universal infant immunization programs. All children should receive three doses of vaccine by the time they are 18 months of age. Scheduling of the three doses is flexible. Two hepatitis B vaccines are currently available in the United States, and both are highly effective and safe. Dosage depends on several factors, including manufacturer, age at vaccination, maternal serologic status for hepatitis B surface antigen and presence of underlying disease. The committees continue to recommend immunization of high risk older children and adults, and immunization of adolescents is encouraged where resources are available.

Adolescent↗

Regional differences in infant immunization against hepatitis B: did intervention work?

OBJECTIVE: The impact of a community intervention to establish hospital nursery policies for universal newborn immunization against hepatitis B was determined by comparing primary care physician immunization practices in two counties, one intervention and one control. METHODS: Surveys were mailed to 855 physicians in 1994; 322 of 533 respondents were eligible, with 155 from San Francisco (SF), the intervention county, and 167 from Sacramento (SAC), the control county. Adoption of universal hepatitis B immunization was defined as immunizing more than 90% of infants seen in 1993. RESULTS: Although similar proportions of physicians agreed, 79% in SF and 72% in SAC, 64% of SF physicians and 40% of SAC physicians adopted universal infant immunization (P < 0.0001). Universal immunization was greater for pediatricians than for family physicians (OR = 2.00, 95% CI 1.66-2.41) but less for physicians who perceived their patients population to be at low risk for hepatitis B compared to those who did not (OR = 0.60, 95% CI 0.45-0.79). While 94% of physicians in both counties indicated their willingness to provide the second and third doses of the hepatitis B vaccine if the first dose had been administered in the newborn nursery, 64% of SF in contrast to 30% of SAC physicians reported routine nursery administration of the vaccine (P < 0.0001). CONCLUSIONS: Primary care physician adoption of universal hepatitis B infant immunization and routine nursery administration of the first dose of the vaccine were both greater in San Francisco than in Sacramento, suggesting impact of a community intervention to increase hepatitis B immunization rates.

Adult↗

Diphtheria in Lithuania, 1986-1996.

Diphtheria reappeared in Lithuania in 1986 and rose to epidemic levels by 1992. Between 1991 and 1996, 110 cases of diphtheria were registered, with an incidence of 0.03-1.15/100,000 population. Most cases (84%) and all 17 deaths occurred among persons >/=15 years, most of whom had never been vaccinated. Persons 40-49 years old had the highest average annual age-specific morbidity (1.70/100,000) and mortality (0.53/100,000) rates. Low levels of immunity among individuals 40-49 years old and migration to epidemic areas in Russia and Belarus contributed to the epidemic's occurrence. Between 1991 and 1995, toxigenic Corynebacterium diphtheriae strains were isolated from 84 of all registered patients (76%), and nontoxigenic strains were isolated from 13 (12%). By 1996, two mass vaccination campaigns, which provided one dose of vaccine to individuals 25-30 years old and three doses of vaccine to persons 31-60 years old, helped reduce the number of cases. The first campaign achieved 69% coverage; the second achieved 48% coverage.

Adult↗

[Investigation on the effect and strategy of polio eradication in Hainan Province].

OBJECTIVE: Hainan Province was a hyperendemic area of poliomyelitis, with an average incidence rate of 0.28 per hundred thousand before 1993. A series of strategy was developed for polio eradication in the whole province in July 1993. METHODS: Health education, regular and strenthening immunization programs, AFP surveillance. RESULTS: 1. OPV vaccination rate increased to 97.93%, 2. incidence rate of polio had a 80.93% reduction, 3. seasonal peak of epidemic was cut down, 4. endemic cycle was broken and 5. the endemic area became smaller. The number of counties (cities) where polio cases occured reduced for 81.33% in 1993 than that in 1989. Four boosters had been implemented from 1993 to 1997, to eliminated blank spots of immunization. The average geometric antibody of titre increased to 1:400 and above. After the establishment of polio surveillance system in 1991, 1. the reporting rate of non-AFP increased from 0 to 1.27 per hundred thousand, 2. rate of double specimens collection increased from 0 to 87.10%, 3. positive rate of virus isolation from 23.07% to 34.80%, 4. the positive specimens were appraised by National Polio Surveillance Center and no wild strain was found. Health education has made remarkable impact and immunization knowledge among parents had a 75 percentage point increase. CONCLUSION: Results showed that strategy of polio eradication has made positive effects and provided valuable experiences for the control or elimination of diseases which can be prevented by vaccines.

Child↗

Current chemotherapy protocols for childhood acute lymphoblastic leukemia induce loss of humoral immunity to viral vaccination antigens.

OBJECTIVE: To evaluate viral vaccination immunity and booster responses in children treated successfully for acute lymphoblastic leukemia by chemotherapy and to study the response to treatment of antibody-producing plasma cells that are important for persistence of humoral immunity. METHODS: Forty-three children who were in continuous first remission for a median of 5 years (range: 2-12 years) were studied. Before the leukemia was diagnosed, all children had been immunized against measles, mumps, and rubella according to the Swedish National immunization program. We analyzed levels of serum antibodies against measles and rubella by enzyme immunoassays. Avidity tests for measles antibodies were concomitantly performed by enzyme-linked immunosorbent assay for measles virus immunoglobulin G detection. The proportion of plasma cells in bone marrow was studied by flow cytometry at different times during treatment and follow-up. Children who lacked protective levels of antibodies to vaccination antigens were reimmunized. Serum was collected 3 months after immunization to assess vaccination responses. RESULTS: After completion of the treatment, only 26 of the 43 children (60%) were found to be immune against measles and 31 (72%) against rubella. The proportion of bone marrow plasma cells decreased during treatment but returned to normal after 6 months. Revaccination caused both primary and secondary immune responses. Six of the 14 children without immunity failed to achieve protective levels of specific antibodies against measles and 3 against rubella. CONCLUSIONS: Our finding of loss of antibodies against measles and rubella in children treated with intensive chemotherapy suggests that reimmunization of these patients is necessary after completion of the treatment. To determine reimmunization schedules for children treated with chemotherapy, vaccination responses need to be studied further.

Adolescent↗

[Respective importance of vertical and horizontal transmission of hepatitis B in the Australian archipelago (French Polynesia). Preliminary results of the vaccination of newborns].

A seroepidemiological survey of hepatitis B was conducted in 1988 in the Austral archipelago (French Polynesia) in a randomly selected sample of 957 persons, has showed an infection rate (at least one positive marker) with HBV of 64.1% for the entire archipelago. Among women of child-bearing age, HBs Ag carriage rate was 11.45% of whom 19.1% were so HBe Ag carriers. Among infants HBs Ag carriage rate was 2.1% and among juveniles it was 10.6%. In this area horizontal transmission of HBV is essential. An immunization program was implemented in August 1988 using a recombinant vaccine (GenHevac BTM). At one year of the program, 97% of the children had received at least one dose of vaccine, 90% had HBs-antibodies titer higher than 10 mUI/ml, 96% had seroconverted for at least one of the two antibodies (anti-HBs and/or anti-preS2) and any of them was neither HBs Ag carrier nor anti-HBc IgM antibodies carrier. Finally, among 7 neonates whose mother were positive for both HBs Ag and HBe Ag, 6 were immunes and the last one, aged of 1 month (one dose received only), was not HBs Ag carrier. These preliminary results show that vaccination with GenHevac BTM to be immunogenic and effective in field conditions.

Adolescent↗

Emerging infectious diseases in an island ecosystem: the New Zealand perspective.

Several unique features characterize infectious disease epidemiology in New Zealand. Historically, well-organized, government-run control programs have eliminated several zoonoses. More recently, however, communicable disease control has been mixed. Rates of rheumatic fever, tuberculosis, and enteric infectious are high, and rates of meningococcal disease are increasing. These diseases are over-represented in New Zealanders of Polynesian descent, who generally live in more deprived and overcrowded conditions than do those of European descent. Measles and pertussis epidemics are recurring because of inadequate vaccine coverage, despite a well-developed childhood immunization program. A progressive response to the HIV epidemic has resulted in relatively low rates of infection, particularly among injecting drug users; however, the response to other sexually transmitted infections has been poor. A key challenge for the future is to build on successful strategies and apply them to persisting and emerging infectious disease threats in a small, geographically isolated country with limited economic resources.

Animals↗

[Hepatitis B in children].

Central to immunization programmes is that hepatitis B virus infection in infancy is much more likely to result in the chronic carrier state than if infection occurs in adulthood. In areas of high endemicity like south-eastern Asia most infections occur when chronically infected women transmit hepatitis B virus to their newborns or when chronically infected children transmit the virus to other children. In the Netherlands, the endemicity is considered low; seroprevalence studies showed that 0.8% of the pregnant women are HBsAg-positive. To prevent mother to child transmission of hepatitis B a national immunization program has recently been implemented to prevent perinatal infection in approximately 450 neonates each year. Horizontal transmission of hepatitis B virus also seems possible in children since persistent carriers are found in (medical) centres and institutions for mentally handicapped. Since hepatitis B infections acquired during early childhood are likely to progress to chronicity and liver disease in adult life some risk factors for children in the Netherlands to contract hepatitis B infection are described and the immunization strategy is discussed.

Child↗

Measles epidemic in Israel-successful containment in the military.

BACKGROUND: Measles vaccination at ages 12-15 months is a routine part of standard health care in developed countries. Nonetheless, the prevention and control of measles outbreaks remain a challenge, owing to incomplete or variable compliance with immunization programs and primary vaccine failure (approximately 5%). In Israel, vaccination coverage against measles is high, yet sero-epidemiological studies conducted in the early 1990s showed that 15% of 18-year-olds were unprotected. METHODS: 1994 there was a countrywide epidemic of measles, which spread to the military. The Israel Defense Forces Medical Corps immediately launched a wide-scale vaccination campaign, targeting primarily field units and training bases, where crowded living conditions are the rule. RESULTS: The immunization campaign led to an abrupt cessation of morbidity in the military. In the civilian sector, where no intervention was undertaken, the epidemic continued for another 4 months. CONCLUSIONS: Institutional measles outbreaks, especially in the presence of crowded conditions or high contact rates, may be effectively controlled by mass vaccination.

Incidence↗

The rationale for population-based surveillance for Haemophilus influenzae type b meningitis.

Although Haemophilus influenzae type b (Hib) conjugate vaccines have been spectacularly successful, nearly eradicating Hib disease in countries where used routinely, they are relatively expensive. In many countries the incidence of Haemophilus influenzae type b (Hib) disease is uncertain, and it is unclear whether the local burden of Hib disease warrants the costs of adding Hib vaccine to the routine immunization program. Population-based surveillance to assess the local burden of Hib disease can help decision makers with this process. Although pneumonia is more common than meningitis, surveillance for Hib meningitis and invasive disease is likely to be more feasible and efficient than surveillance for Hib pneumonia. Standardization of laboratory methods for the isolation and identification of H. influenzae from CSF specimens is essential to successful surveillance. Should a country decide to introduce Hib conjugate vaccine as a routine immunization, population-based surveillance data collected before and after the introduction of vaccine can be used to monitor its impact. Finally population-based surveillance for bacterial meningitis also can provide information on the incidence of pneumococcal and meningococcal infections and on serogroup or serotype distributions that will be important when evaluating the new vaccines for those pathogens that are being developed.

Child, Preschool↗

Protective effect of immunization with heat-labile enterotoxin in gnotobiotic rats monocontaminated with enterotoxigenic Escherichia coli.

The protective effect of active immunization with a purified preparation of the polymyxin-release form of Escherichia coli heat-labile enterotoxin (LT), administered using a parenteral prime and peroral boosts given after ablation of gastric secretion by means of cimetidine, was assessed in gnotobiotic rats which were challenged by monocontamination with enterotoxigenic strains of E. coli. Water transport was evaluated by the in vivo marker perfusion technique at weekly intervals over a 3-week period after contamination. Water transport in unimmunized control rats was consistently in absorption in those contaminated by a nontoxigenic strain, in secretion during only week 2 in those contaminated by an LT(+)/- strain, in secretion during weeks 2 and 3 in those contaminated by an LT(+)/ST(+) (heat-stable enterotoxin) strain, and consistently in absorption in those contaminated by an -/ST(+) strain. Rats immunized with a booster dosage of 250 mug had a significant increase (P < 0.001) in net water absorption as compared to unimmunized rats, with values in the borderline range of absorption, when challenged with either the LT(+)/- or LT(+)/ST(+) strains. Rats immunized with a 10-fold-higher boosting dosage had a significant increase (P < 0.001) in net water absorption as compared to those boosted at the lower dosage; water absorption was within the normal range. There was no difference between the ileal bacterial counts of unimmunized and immunized rats challenged by the various strains. These observations indicate that this immunization program provides complete protection in an animal model against challenge by intestinal contamination with enterotoxigenic strains of E. coli which produce LT, either alone or in combination with ST.

Animals↗

Immunization procedure-related immunoglobulin levels in the development of antibodies against Cysticercus cellulosae.

Various immunization procedures were investigated in an effort to improve the number of hybridomas producing antibodies against Cysticercus cellulosae. Ten groups of 5 BALB/c mice were subjected to different immunization procedures and were bled repeatedly over a period of 68 days. The samples of sera thus obtained were tested by enzyme linked immunosorbent assay: total immunoglobulins, IgG and IgM levels were determined. In general, total anticyst antibody titres increased during the course of immunization but in 3 groups the final titre was lower than the maximal antibody titre. Overall, immune tolerance did not appear to be a problem and longer immunization programs seemed to end with slightly higher antibody levels. So far, 4 mice from the group that exhibited the highest immunoglobulin levels have been used for hybridoma production. Out of 124 hybridomas thus obtained, only 1 secreted antibodies against Cysticercus cellulosae.

Animals↗

Emergency response vaccines--a challenge for the public sector and the vaccine industry.

In partnership with industry, WHO has developed a number of strategies to facilitate access to vaccines recommended for use in national immunization programs. These strategies have been necessitated by the increasing fragility of vaccine supply for developing markets. The potential global spread of epidemic disease has made it imperative to expand these efforts. A new concept is proposed, that of essential vaccines, defined as "vaccines of public health importance that should be accessible to all people at risk". Essential vaccines will include emergency response vaccines that have become important due to resurgent outbreaks, threatening global pandemics, and situations where a global emergency immunization response may be needed. While some of the approaches already developed will be applicable to emergency response vaccines, other novel approaches requiring public sector intervention will be necessary. Procurement, financing and allocation of these emergency response vaccines, if left to governments or private individuals based on ability to pay, will threaten equitable access. The challenge will be to ensure development of and equitable access to these vaccines while not threatening the already fragile supply of other essential vaccines.

Emergencies↗

Diphtheria epidemic in the Republic of Georgia, 1993-1997.

Epidemic diphtheria reemerged in the republic of Georgia in 1993. From 1993 to 1997, 1405 cases were reported (28 in 1993, 312 in 1994, 429 in 1995, 348 in 1996, and 288 in 1997), with a cumulative incidence of 25.8/100,000 and a case fatality ratio of 9.5%. During 1993-1997, 53% of the diphtheria cases occurred among persons >/=15 years of age. Unvaccinated patients were more likely to have toxic forms (relative risk=2.24; 95% confidence interval=1.69-2.96) or to die of diphtheria (relative risk=2.24; 95% confidence interval=1. 36-3.68) than those who had received at least one dose of diphtheria toxoid. Improvement in routine childhood vaccination coverage and implementation of mass adult vaccination campaigns have been critical to bringing the epidemic under control. By mid-1998, the overall diphtheria situation in Georgia appeared to have been controlled. Only 53 cases were reported from January to June 1998, representing a 64% decrease from the 148 cases during the corresponding period in 1997.

Adolescent↗