Clinician satisfaction with vaccination visits and the role of multiple injections, results from the COVISE Study (Combination Vaccines Impact on Satisfaction and Epidemiology)

Because little is known about clinician satisfaction with infant vaccination visits, we measured satistaction and the effects of the number of injections on satisfaction. Clinicians from 35 pediatric centers self-administered a questionnaire using visual analog scales augmented by a Likert scale. All 95 pediatricians and 137 nonphysician vaccinators responded. In both populations, increased injections predicted decreased overall satisfaction, and decreased satisfaction with obtaining consent, time to prepare/administer, getting upset during administration, and time to update records (each p<0.01). Satisfaction decreased markedly, on each measure, at 4-injection visits, 5-injection visits, or both.

Considerations for hepatitis B as part of a combination vaccine

BACKGROUND

In 1991 the Advisory Committee on Immunization Practices (ACIP) developed a comprehensive strategy to eliminate the transmission of hepatitis B virus in the United States, which includes immunization of all infants. Today, as the number of recommended childhood vaccinations increases, combination vaccines are needed to simplify the immunization schedule and improve coverage levels.

METHODS

A review of the literature was performed to determine the considerations that should be taken when hepatitis B virus vaccine (HepB) is included as part of a combination vaccine.

RESULTS

A combination vaccine that incorporates HepB and other routine infant vaccine antigens has been developed for administration at 2, 4 and 6 months of age. Clinical studies have demonstrated that administration of HepB, either as a monovalent or combination vaccine at 2, 4 and 6 months of age, induces a seroprotective immune response similar to that achieved with monovalent HepB administered at 0, 1 and 6 months of age. In addition the combination vaccine results in similar or fewer adverse reactions compared with separate administration of its components. Infants given a dose of monovalent HepB at birth will receive a total of four doses of HepB when the combination is used. The extra dose of HepB has not led to increased adverse reactions.

CONCLUSIONS

A HepB-containing combination vaccine administered at 2, 4 and 6 months of age is as safe and immunogenic as separate administration of its components and will help simplify the childhood immunization schedule.

Update on the development and use of viral and bacterial vaccines for the prevention of acute otitis media

Acute otitis media (AOM) is the most frequent diagnosis in physician offices among children 1-4 years of age. Viruses that cause upper respiratory tract infections (i.e., respiratory syncytial virus [RSV], influenza virus, parainfluenza virus [PIV], and others) play an important role in the development of AOM. Prevention of infections with these viral pathogens likely would reduce the incidence of AOM. In three previous studies, influenza virus vaccines showed 30-36% efficacy against the development of AOM. Vaccines to prevent infections with RSV and PIV type 3 are undergoing clinical testing at this time. The three major bacterial pathogens causing AOM are Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis. Pneumococcal conjugate vaccine, licensed in the United States in 2000, was shown in two pivotal trials to reduce the incidence of all causes of AOM by 6%, pneumococcal AOM by 34%, and pneumococcal AOM caused by serotypes contained in the vaccine by 57%. Currently, vaccines against NTHi and M. catarrhalis are under development.

Antibody responses to bovine parainfluenza virus type 3 (PIV3) vaccination and human PIV3 infection in young infants

A phase 2 clinical trial was conducted to evaluate the antibody responses to bovine parainfluenza virus type 3 (bPIV3) vaccination in young infants. Three groups were tested as follows: placebo (n=66) and 10(5) (n=64) or 10(6) (n=62) TCID(50) of bPIV3. The vaccine or placebo was administered intranasally at ages 2, 4, 6, and 12-15 months, and serum specimens were collected at ages 2, 6, 7, 12-15, and 13-16 months. Serum hemagglutination inhibition (HI) and IgA antibody titers against bPIV3 and human PIV3 (hPIV3) were measured. The results indicate that antibody responses to bPIV3 vaccination are more likely to be detected by the bPIV3 IgA and HI assays than by the hPIV3 IgA and HI assays, that bPIV3-induced antibody response can be differentiated from hPIV3-induced antibody response most reliably by comparing bPIV3 and hPIV3 HI titers, and that bPIV3 vaccine prevents vaccine recipients from developing antibody profiles of hPIV3 primary infection.

Vaccine prevention of acute otitis media

The incidence of acute otitis media (AOM) in infants and young children has increased dramatically in recent years in the United States. AOM often follows upper respiratory tract infections due to pathogens such as respiratory syncytial virus (RSV), influenza virus, and parainfluenza virus (PIV). These viruses cause eustachian tube dysfunction that is critical to the pathogenesis of AOM. Vaccines against these viruses would likely reduce the incidence of AOM. In three previous studies, influenza virus vaccines reduced the incidence of AOM by 30% to 36%. Vaccines to prevent infections with RSV and PIV type 3 are undergoing clinical testing at this time. Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis are the three most common AOM pathogens. Heptavalent pneumococcal conjugate vaccine is effective in preventing invasive disease and AOM caused by serotypes contained in the vaccine. Vaccine candidates for NTHi and M. catarrhalis are under development.

Immunogenicity of a Haemophilus influenzae type b-tetanus toxoid conjugate vaccine when mixed with a diphtheria-tetanus-acellular pertussis-hepatitis B combination vaccine

BACKGROUND

Combination vaccines are urgently needed to reduce the number of injections given to young children. The aim of the study was to evaluate the safety and immunogenicity of a combination vaccine that contains diphtheria and tetanus toxoids and acellular pertussis antigens (DTaP), recombinant hepatitis B surface antigen (HepB) and Haemophilus influenzae type b (Hib) polysaccharide conjugated to tetanus toxoid (PRP-T).

METHODS

Four hundred five infants were randomized equally to three groups and immunized at 2, 4 and 6 months of age with: (1) DTaP/HepB vaccine used to reconstitute lyophilized PRP-T vaccine and administered as a single injection; (2) DTaP/HepB vaccine and PRP-T vaccine administered as two separate injections; or (3) DTaP, HepB and PRP-T vaccines administered as three separate injections. Safety was closely monitored, and blood specimens were obtained to assess antibody responses to each vaccine antigen.

RESULTS

All study vaccines were well-tolerated, and the rates of systemic and injection site reactions were similar between groups. After the third dose the geometric mean antibody concentrations to Hib were significantly lower in subjects in Group 1 (1.63 microg/ml) compared with subjects in Groups 2 and 3 (6.26 and 6.15 microg/ml, respectively; P < 0.0001). Subjects with antibody concentrations <1.0 microg/ml after the third dose responded well to a booster dose of Hib conjugate vaccine given at 11 to 15 months of age (41 of 44 with anti-PRP > or = 1.0 microg/ml). Differences between groups for antibody responses to the other vaccine components were not clinically significant.

CONCLUSIONS

Infants given a combined DTaP/ HepB/PRP-T vaccine experienced a significantly lower antibody response to the PRP-T component than infants given PRP-T vaccine as a separate injection. However, the immune response to a booster dose of Hib conjugate vaccine indicated the presence of immunologic memory.

Immunogenicity of a heptavalent pneumococcal conjugate vaccine in Apache and Navajo Indian, Alaska native, and non-native American children aged <2 years

High rates of invasive pneumococcal disease have been described among infants living in various Native American communities. In this study, we evaluated the immunogenicity of a 7-valent pneumococcal vaccine consisting of serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F covalently linked to the outer membrane protein complex of Neisseria meningitidis in Apache and Navajo Indian, Alaska Native, and non-Native American children. The vaccine was administered at ages 2, 4, and 6 months; a booster dose was given at age 15 months. Levels of serotype-specific immunoglobulin G (IgG) were measured by a standardized enzyme-linked immunosorbent assay. The responses after 3 primary doses of vaccine were similar in all 3 groups of children, except for those to serotypes 14 and 23F. One month after the booster dose, geometric mean concentrations (GMCs) of serotype-specific IgG antibodies increased significantly in all 3 groups of children, compared with GMCs of IgG antibodies to pneumococcal serotypes before the booster dose.

Epidemiology of invasive pneumococcal disease in southern California: implications for the design and conduct of a pneumococcal conjugate vaccine efficacy trial

Population-based prospective surveillance of invasive pneumococcal disease was done in Southern California from 31 March 1992 to 1 April 1995; 814 cases were identified, for an incidence of 12.5/100,000 persons/year. The incidence among persons < or = 2, < or = 5, and > or = 65 years of age was 145, 72, and 32/100,000, respectively. More than 95% of cases included bacteremia; incidence of meningitis was 0.8/100,000. Among children < or = 2 years of age, 79% of isolates were obtained in the outpatient setting, compared with 16% of isolates among persons > or = 15 years of age. Eighty percent of isolates were serotypes included in heptavalent pneumococcal conjugate vaccines currently being evaluated. Children < or = 2 years of age were at highest risk of having an isolate resistant to penicillin. Among resistant isolates, high-level resistance increased from 4% to 21% over a 3-year period. Prospective epidemiologic data are needed to perform a protective efficacy trail of pneumococcal conjugate vaccines in infants, among whom most invasive pneumococcal disease is vaccine-preventable.

Comparative safety and immunogenicity of two recombinant hepatitis B vaccines given to infants at two, four and six months of age

OBJECTIVES

To evaluate the relative safety and immunogenicity of the two recombinant hepatitis B vaccines licensed in the United States with doses recommended for routine immunization of low risk infants and a schedule that corresponds with routine pediatric visits.

METHODS

Healthy infants were immunized at 2, 4 and 6 months of age with hepatitis B vaccine manufactured by either SmithKline Beecham (Engerix-B, 10 micrograms/dose, n = 228) or Merck and Co. (Recombivax HB, 2.5 micrograms/dose, n = 200). Adverse reactions were ascertained by parental reports and interviews and by review of medical records. Antibody concentrations to hepatitis B surface antigen (anti-HBs) were measured in sequential serum specimens by enzyme immunoassay.

RESULTS

Adverse reactions were mild and the rates were not significantly different between the two groups. After the first and second doses the rates of seropositivity (> or = 10 mIU/ml) and seroprotection (> or = 10 mIU/ml) were significantly higher in infants given SmithKline Beecham vaccine (P < 0.01). After the second and third doses infants given SmithKline Beecham vaccine also had significantly higher geometric mean anti-HBs concentrations compared with those given Merck vaccine (348.0 mIU/ml vs. 66.9 and 1914.8 mIU/ml vs. 514.8 mIU/ml, respectively, P < 0.001). Nevertheless after the third dose 99% of infants in both vaccine groups achieved seroprotective antibody concentrations.

CONCLUSIONS

Both recombinant hepatitis B vaccines were safe and immunogenic when administered concurrently with other pediatric vaccines at 2, 4 and 6 months of age, but earlier protective responses were observed with the SmithKline Beecham vaccine than with the Merck vaccine.

Safety and immunogenicity of a recombinant hepatitis B vaccine administered to infants at 2, 4 and 6 months of age. The Kaiser-UCLA Vaccine Study Group

A recombinant hepatitis B vaccine was administered to over 5000 infants in a prospective, randomized and blinded study. Infants were given either recombinant hepatitis B vaccine (Engerix-B, SmithKline Beecham Pharmaceuticals, 10 micrograms dose-1) or a Haemophilus influenzae type b (Hib) conjugate vaccine at 2, 4 and 6 months of age simultaneously with diphtheria-tetanus-pertussis and oral polio vaccines. Adverse reactions were ascertained by parental reports and interviews, and review of medical records. Blood specimens collected from 269 infants given hepatitis B vaccine were assayed for antibody to hepatitis B surface antigen (anti-HBs) by enzyme immunoassay. Infants given hepatitis B vaccine experienced low rates of adverse reactions that were similar or lower than the rates in infants given Hib conjugate vaccine. The geometric mean anti-HBs concentrations were 9.6 mIU ml-1 after one dose, 333 mIU ml-1 after two doses and 1812 mIU ml-1 after three doses (99% had levels > or = 10 mIU ml-1). Antibody responses to diphtheria and tetanus toxoids were unaffected by simultaneous administration of hepatitis B or Hib conjugate vaccine. Engerix-B vaccine was safe and immunogenic when given with other routine childhood immunizations at 2, 4 and 6 months of age, and should provide long-term protection against hepatitis B virus infection.

Effect of neonatal immunization with diphtheria and tetanus toxoids on antibody responses to Haemophilus influenzae type b conjugate vaccines

We randomly assigned 150 newborn infants to receive diphtheria and tetanus toxoids (DT) or Hib oligosaccharide conjugate (HbOC) at birth to determine whether exposure to the Haemophilus influenzae type b (Hib) conjugate vaccines' carrier proteins would enhance immune responses to subsequent administrations of HbOC or PRP-tetanus toxoid conjugate (PRP-T) at 2, 4, and 6 months of age. Their antibody responses were compared with those of 100 children immunized with HbOC or PRP-T beginning at 2 months of age. No serious adverse reactions were associated with neonatal vaccination. Administration of HbOC at birth did not lead to earlier or higher antibody levels. Newborn immunization with DT did not prime children for enhanced antibody responses. Moreover, Hib antibody levels were lower in DT-primed children than in children immunized beginning at 2 months of age. Diphtheria antibody levels, but not tetanus antibody levels, were also lower in children immunized with DT at birth. We conclude that neonatal immunization with Hib conjugate vaccines is not a means to provide earlier protection against invasive Hib disease. Newborn DT administration does not enhance subsequent antibody responses to Hib conjugate vaccines, and may lead to suppression of Hib and diphtheria antibody responses.

Enhanced antibody responses in infants given different sequences of heterogeneous Haemophilus influenzae type b conjugate vaccines

To evaluate the safety and immunogenicity of differing sequences of heterogeneous Haemophilus influenzae type b (Hib) conjugate vaccines, we randomly assigned 300 infants to one of six vaccination schedules. At 2, 4, and 6 months of age, subjects were given single or heterogeneous vaccines: Hib polysaccharide (PRP) conjugated to mutant diphtheria toxin (HbOC), PRP conjugated to outer-membrane protein of Neisseria meningitidis (PRP-OMP), or PRP conjugated to tetanus toxoid (PRP-T). No serious reactions were attributable to immunization with heterogeneous vaccines, and there were few significant differences in the rates of minor adverse reactions among groups. PRP-OMP was the only vaccine that induced an antibody response after the first dose, but significant booster responses were not seen after the second and third doses. Subjects given PRP-T vaccine responded well after two doses, but three doses of HbOC vaccine were needed for an equivalent antibody response. All the Hib vaccine schedules evaluated were immunogenic, and schedules initiated by PRP-OMP vaccine at 2 months of age, followed by two doses of either HbOC or PRP-T vaccine at 4 and 6 months of age, induced the highest antibody levels after each dose. Such schedules may be the best for protecting infants and children who are at greatest risk of having invasive Hib disease, such as American Indian children.

Immunogenicity of Haemophilus influenzae type b tetanus toxoid conjugate vaccine in young infants. The Kaiser-UCLA Vaccine Study Group

In a prospective, randomized, double-blind efficacy trial, the immunogenicity of 10 lots of Haemophilus influenzae type b capsular polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) was evaluated. More than 10,000 infants received PRP-T or hepatitis B vaccine at about 2, 4, and 6 months of age along with other childhood vaccines. In a subset of infants, geometric mean concentrations of total anticapsular antibody were 0.08, 0.79, and 5.29 micrograms/mL after the first, second, and third doses, respectively. Four lots of reconstituted lyophilized PRP-T vaccine were significantly more immunogenic than 6 lots of aqueous vaccine (P = .03). In a stepwise regression model, the most important additional factors affecting anticapsular antibody concentrations were the time between the third dose and the blood draw, race, and breast-feeding status at 6 months of age. Immune responses to diphtheria and tetanus toxoids were not significantly different for infants given PRP-T or hepatitis B vaccines along with diphtheria-tetanus toxoid-pertussis vaccine.

Protection provided by Haemophilus influenzae type b conjugate vaccines in Los Angeles County: a case-control study

The objective was to assess the degree of disease control and to evaluate the protective efficacy of licensed Haemophilus influenzae type b (Hib) conjugate vaccines (HbOC, PRP-OMP, PRP-D) used routinely in children 2 to 35 months of age. We conducted a case-control study in Los Angeles County between January 1, 1991, and December 31, 1992, and a cohort analysis of Hib cases between 1983 and 1992. For the case-control study 105 cases of invasive Hib disease were identified and 767 geographically and age-matched controls were selected by random digit telephone dialing. Sixteen HbOC vaccine failures occurred > 14 days after a single dose of vaccine, 6 vaccine failures after 2 doses and 3 failures after 3 doses; 2 cases occurred 6 and 12 days, respectively, after an initial dose of HbOC. The protective efficacy of a single HbOC vaccine dose was 71.1% (95% confidence interval (CI), 37.5 to 87.2%). After 2 doses the efficacy was 88.8% (95% CI, 59.5 to 96.9%) and after 3 doses it was 94.4% (95% CI, 68.0% to 99.0%). Similar 95% CIs were seen for 1 and 2 doses of PRP-OMP vaccine. Adjustment of efficacy estimates for potential confounding variables did not significantly alter the results. Despite relatively low rates of immunization (20 to 60%) the rates of Hib disease decreased strikingly between 1990 and 1992 (from 24.2 to 4.4/100,000 children < 5 years of age). The HbOC conjugate vaccine, used predominantly but incompletely during this period, provided substantial protection against invasive Hib disease in children immunized between 2 and 35 months of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Eradication of Haemophilus influenzae type b disease in southern California. Kaiser-UCLA Vaccine Study Group

OBJECTIVE

To assess the effects of Haemophilus influenzae vaccination of infants.

RESEARCH DESIGN

We evaluated H influenzae type b (Hib) disease rates in Los Angeles County, California (population, 9 million; 1983 through 1992), and in the Southern California Kaiser Health Plan (2.5 million enrollees; 1988 through 1992) during the past decade. Cases were obtained through active and passive disease surveillance in the two populations. The following vaccines were used during the study period (1983 through 1992): (1) Hib polysaccharide vaccine (polyribosyl ribitol phosphate) (used from 1985 through 1987 for children 24 through 60 months of age); (2) Hib polysaccharide-diphtheria toxoid conjugate, Hib polysaccharide CRM197 mutant diphtheria toxoid conjugate vaccine, and Hib polysaccharide outer-membrane protein of group B meningococcus conjugate vaccine in older children (1988 through 1990; ages 15 through 60 months); and (3) Hib polysaccharide CRM197 mutant diphtheria toxoid conjugate vaccine and Hib polysaccharide outer-membrane protein of group B meningococcus conjugate vaccine used in infants (1991 through 1992).

MEASUREMENTS AND RESULTS

Between 1983 and 1988, the Hib disease incidence in Los Angeles County was unchanged (32.7 to 42.5/100,000 person-years in children younger than 5 years). In 1989 through 1990, before Hib conjugate licensure for infant use, Hib disease rates in all age groups declined. After licensure of Hib vaccines for infants in 1990, there was a further fivefold decrease in infants. More dramatic decreases occurred in the better-immunized Kaiser Health Plan children aged 0 through 60 months (53 cases in 1989, only two cases in 1992).

CONCLUSIONS

The Hib disease has been nearly eradicated in a fully immunized population (Kaiser Health Plan), and significant reductions have also occurred in Los Angeles County.

Effectiveness and safety of an Haemophilus influenzae type b conjugate vaccine (PRP-T) in young infants. Kaiser-UCLA Vaccine Study Group

OBJECTIVE

To study the safety, immunogenicity, and protective efficacy of the Haemophilus influenzae capsular polysaccharide tetanus conjugate vaccine (PRP-T).

DESIGN

Randomized, double-blind, controlled clinical trial.

SETTING

Southern California Kaiser-Permanente Health Plan.

PARTICIPANTS

10,317 infants 6 to 15 weeks of age, with no known immune dysfunction, exposure to hepatitis B, or contraindication to diphtheria-tetanus-pertussis (DTP) vaccination were enrolled between August 1989 and September 1990.

INTERVENTION

Infants were randomized to receive either PRP-T or a recombinant hepatitis B control vaccine (in addition to DTP) at approximately 2, 4, and 6 months of age.

OUTCOME MEASURES

Adverse reactions occurring during the first 72 hours and between doses (including hospitalizations and outpatient visits) were measured using parental reporting/interviews and review of records. Invasive disease caused by H influenzae was ascertained from the time of enrollment until December 31, 1990.

RESULTS

In October 1990, the study was prematurely terminated because of licensure of other H influenzae vaccines recommended for routine infant use. The rates of systemic and local reactions occurring within 72 hours of each vaccine dose were generally similar for infants given PRP-T and hepatitis B, but some reaction rates (local reactions, fever > or = 102 degrees F, irritability, crying) were significantly higher in the PRP-T group. In the month following receipt of vaccine, PRP-T-vaccinated infants experienced five definite seizures compared with three in the hepatitis B control group. Within 48 hours of vaccination, three seizures (two definite and one possible), which were thought to be related to vaccination, occurred in the PRP-T group, compared with none in the control group (P < .13). Overall morbidity, mortality, and hospitalization rates were similar in the two vaccine groups. Three cases of invasive disease caused by H influenzae occurred in the control group; none occurred in the PRP-T group.

CONCLUSIONS

The PRP-T vaccine is safe and appears to be effective in preventing invasive disease caused by H influenzae type b.

Pediatric experience with recombinant hepatitis B vaccines and relevant safety and immunogenicity studies

Yeast-derived recombinant hepatitis B vaccines have replaced plasma-derived vaccines in the United States and have now been given to millions of infants and children throughout the world. Routine immunization of infants in the United States with hepatitis B vaccine has been endorsed as the optimal means to prevent infection. The recombinant vaccines have an excellent safety record; most children have no adverse reactions whereas a few experience only minor local and systemic reactions that resolve within a short time. Both of the vaccines licensed in the United States are highly immunogenic in infants and children who complete a three dose vaccination sequence. Approximately 95 to 100% achieve protective levels of antibody to hepatitis B surface antigen (> or = 10 mIU/ml) after three doses. Immunization may begin at birth or at 1 to 2 months of age, and hepatitis B vaccine may be given simultaneously with other routine childhood vaccines. Antibody levels to hepatitis B surface antigen gradually wane over time, and the duration of maintaining protective levels correlates strongly with the peak level achieved. The protective efficacy against perinatal transmission from mothers who are positive for hepatitis B surface antigen and e antigen is 90 to 100% when the first dose of vaccine is administered at birth with hepatitis B immunoglobulin. In highly endemic populations immunization in infancy also protects against horizontal transmission from chronically infected family members. Studies currently in progress will determine the duration of protection, the potential need for booster doses and the feasibility of combining antigens in multivalent vaccines.

Anti-PRP antibody levels after a primary series of PRP-OMPC and persistence of antibody titres following primary and booster doses

The Haemophilus influenzae capsular polysaccharide-outer membrane protein conjugate, PRP-OMPC (PedvaxHIB) elicits very good antibody responses in infants > or = 2 months of age after the first dose. Increasing age at time of first vaccination correlates with higher antibody responses. Anti-PRP responses are consistently high with the first injection among all population groups studied. Booster doses stimulate anamnestic antibody responses after one year of age. Among US children (excluding Navajo and Apache children) given a primary injection at 14-18 months of age, the geometric mean titre (GMT) after 2 to 3 years was > 1 micrograms/ml. US children (excluding Navajo and Apache children) given a primary series at 2 and 4 months of age and a booster at 18 months of age also had an anti-PRP GMT > 1 micrograms/ml 2.5 years later. Navajo and Apache children given a primary series at 2 and 4 months of age and a booster at 12-15 months had antibody levels of 1.50 micrograms/ml one year later. Antibody persistence data suggest there will be long-term protection against Haemophilus influenzae b disease following immunization with PRP-OMPC.

Risk factors for invasive Haemophilus influenzae type b in Los Angeles County children 18-60 months of age

Potential factors that confer risk or protection for invasive Haemophilus influenzae type b disease were evaluated in Los Angeles County children 18-60 months of age by case-control methods. In this age group, 79 H. influenzae type b cases were identified by overlapping surveillance methods, and 221 random controls were selected by random digit dialing. Cases and controls were similar in sex, prior health, proportion attending day care, parental educational level, history of breast feeding, and proportion vaccinated with measles/mumps/rubella vaccine. The effect of H. influenzae type b vaccination was controlled in all analyses, and results of vaccine efficacy have been reported elsewhere. Cases were more likely to have a significant underlying medical condition, reside in home with more than six residents, have a lower yearly household income, have two or more smokers in the home, and to be black. Using conditional logistic regression models, the following were significant independent risk factors after adjusting for age, month of diagnosis, H. influenzae type b vaccine status, and the other factors: 1) more than two smokers in the house (odds ratio (OR) = 6.00; 95% confidence interval (CI) 1.49-24.06); 2) household size of more than six persons (OR for more than six vs. less than three persons = 3.71; 95% CI 1.10-12.60); and 3) black maternal race (OR for black vs. Hispanic = 3.47; 95% CI 1.41-8.53). We conclude that exposure to smoking in the home, living in households with more than six members, and the black race are each independently associated with an increased risk for H. influenzae type b disease in Los Angeles County children and, when combined, constitute a major reason for H. influenzae type b disease occurrence.

Protective efficacy of Haemophilus influenzae type b polysaccharide and conjugate vaccines in children 18 months of age and older

To evaluate the protective efficacy of polyribosylribitol phosphate (PRP) and polyribosylribitol phosphate-diphtheria toxoid (PRP-D) vaccines in children 18 to 59 months of age, we conducted a case-control study in Los Angeles (Calif) County between July 1, 1988, and July 31, 1989. Seventy-nine children with invasive Haemophilus influenzae type b disease 18 to 59 months of age were identified, and 212 controls were selected by random-digit telephone dialing methods. Cases and controls were stratified by age and month of disease onset of the case. Seventeen PRP vaccine failures and two PRP-D vaccine failures occurred more than 2 weeks after vaccination. The PRP vaccine was shown not to be effective (point estimate--47%; 95% confidence interval,--307% to 47%), but the PRP-D vaccine was 88% protective (95% confidence interval, 42% to 97%). Adjustment of the efficacy estimates for potential confounding variables did not change the results significantly. The PRP-D vaccine provided significantly better protection than the PRP vaccine against invasive H influenzae type b disease in this population.

Prevention of bacterial meningitis. Vaccines and chemoprophylaxis

The morbidity and mortality caused by bacterial meningitis remains significant despite advances in antimicrobial therapy and supportive care. Prevention of meningitis by routine immunization of infants, who are at greatest risk, offers the only practical way of reducing the incidence of this disease. Widespread use of the recently developed protein conjugate vaccines against Haemophilus influenzae type b by itself could reduce the incidence of bacterial meningitis in the U.S. by more than half. To prevent disease caused by the other pathogens, an effective vaccine against the group B meningococcus must be developed, and the immunogenicity of the pneumococcal and quadrivalent meningococcal vaccines should be improved. Until such time that universal immunization of infants with highly immunogenic vaccines is possible, continued efforts must focus on targeting immunization at high-risk individuals and using chemoprophylaxis to prevent secondary disease where indicated. Addendum: On October 4, 1990, the U.S. Food and Drug Administration licensed the praxis Haemophilus influenzae type b-protein conjugate vaccine (Hboc) for use in infants at 2, 4, and 6 months of age with a booster dose at 15-18 months. Physicians are directed to statements by the Immunizations Practices Advisory Committee and the American Academy of Pediatrics for official recommendations concerning its use.

Safety evaluation of PRP-D Haemophilus influenzae type b conjugate vaccine in children immunized at 18 months of age and older: follow-up study of 30,000 children

We evaluated the safety of the PRP-D conjugate Hib vaccine (ProHIBit, Connaught) in 29,309 children vaccinated at 18-60 months of age in the Southern California Kaiser Permanente medical clinics during the period April 1, 1988, to July 31, 1989. Surveillance for potential reactions involved postcard questionnaires, telephone surveys, reports of Kaiser staff and review of hospitalizations and covered two periods following immunization: (1) the first 48 hours and (2) days 2 through 30. Surveillance for invasive Hib disease involved the above methods in addition to systematic reviews of laboratory and hospital records through January 31, 1990. Rates of local and systemic reactions within 48 hours of vaccination with PRP-D alone were low (less than or equal to 2% for fever greater than 102 degrees F, local redness or swelling) and similar to those previously reported after vaccination with PRP. Hospitalization and seizures (0.15% and 0.09% of vaccinated children, respectively) occurring within 1 month of immunization appeared to be unrelated to vaccination. One 29-month-old child had onset of a fatal episode of Hib sepsis/meningitis within 48 hours of vaccination. Also, a 30-month-old child developed Hib meningitis 10 months after PRP-D vaccination. We conclude that PRP-D is safe when given alone or in combination with other childhood vaccines between 18 and 60 months of age.

Antibody responses to protein A in patients with Staphylococcus aureus bacteremia and endocarditis

To assess the significance of antibody to Staphylococcus aureus protein A (SpA) in human sera, we developed a modified enzyme-linked immunosorbent assay (ELISA). SpA antibody levels in 23 patients with S. aureus endocarditis (IE), 21 patients with non-IE S. aureus bacteremia, and 33 controls were measured. Geometric mean levels of antibody to SpA were significantly higher in S. aureus IE patients (134 ELISA units [EU]) than in uninfected controls (52 EU; P less than 0.01). Also, a significantly greater proportion of S. aureus IE patients (12 of 23) and S. aureus non-IE bacteremia patients (11 of 21) had antibody levels greater than an arbitrary threshold of 100 EU compared with uninfected controls (0 of 23; P less than or equal to 0.001). However, no significant differences in geometric mean SpA antibody levels between the bacteremic patients with and without IE were noted. The sensitivity and specificity of this ELISA to distinguish patients with S. aureus IE from those with non-IE bacteremia were low (52 and 48%, respectively). There was a significant association between SpA antibody levels and either immunoglobulin G or immunoglobulin M teichoic acid antibody levels (r = 0.406, P less than 0.05; r = 0.571, P = 0.002, respectively). For patients from whom multiple sera were available (13 IE and 5 non-IE patients), SpA antibody levels were measured over time and showed a wide temporal variation of immune responses. We conclude that antibody responses to SpA can be measured in many patients with invasive S. aureus disease but that the levels are of insufficient sensitivity or specificity to be of clinical use as a diagnostic or prognostic test.

Computer graphics visualization for acoustic simulation

Computer simulations can be used to generate the spatial and temporal data describing the acoustical behavior of performance halls, but typically the analytical results are difficult to assimilate and compare. By using computer graphics to display the multi-dimensional data, substantially greater amounts of information than that conveyed by standard techniques can be communicated to the designer. This allows designs of different acoustical spaces to be tested, evaluated, and compared.An example comparing the acoustical behavior of three different concert halls demonstrates these techniques and allows for the simultaneous assimilation of much of the information necessary to evaluate the acoustical nature of a space. The use of three-dimensional images, color, animation and abstract representation allows for the comprehension of the complex results of a scientific simulation. Specifically, the simultaneous display of particular icons familiar to the discipline enabled the simultaneous presentation of up to twelve parameters.From a more general point of view, the procedures demonstrate how computer graphics can be utilized for the portrayal of multi-dimensional time dependent data. The visualization techniques are potentially useful for the display of three-dimensional vector fields in many scientific and design applications.

Light Reflection Models for Computer Graphics

During the past 20 years, computer graphic techniques for simulating the reflection of light have progressed so that today images of photorealistic quality can be produced. Early algorithms considered direct lighting only, but global illumination phenomena with indirect lighting, surface interreflections, and shadows can now be modeled with ray tracing, radiosity, and Monte Carlo simulations. This article describes the historical development of computer graphic algorithms for light reflection and pictorially illustrates what will be commonly available in the near future.

Protective efficacy of protein A-specific antibody against bacteremic infection due to Staphylococcus aureus in an infant rat model

Staphylococcal protein A (SpA) is a potent antiphagocytic component of the cell wall of most pathogenic Staphylococcus aureus strains. We studied the in vitro opsonophagocytic and in vivo protective activities of rabbit immunoglobulin G (IgG) antibody to purified SpA obtained from two unencapsulated S. aureus strains (Cowan I and 17A). Postimmune serum contained high titers of specific IgG to SpA, as measured by a modified enzyme-linked immunosorbent assay that blocked nonspecific binding of IgG to SpA. In vitro, both S. aureus strains were efficiently phagocytosed and killed by polymorphonuclear leukocytes in the presence of nonimmune sera and complement. With one strain (Cowan I), opsonophagocytosis was significantly enhanced in the presence of SpA antibody, but with the other strain (17A), killing was significantly decreased with immune serum. We then evaluated the potential protective benefit of SpA antibody in preventing S. aureus bacteremia in infant rats. Two-day-old rats received saline or various doses of SpA antiserum and were challenged subcutaneously 1 day later, but even the highest levels of antibody did not significantly reduce mortality, bacteremia or metastatic infection to lungs or liver (frequency or magnitude). This lack of protective efficacy was not related to a failure of SpA F(ab')2 to bind to cell surface-exposed epitopes, since F(ab')2 fragments prepared from hyperimmune serum bound avidly to the whole organism in an enzyme-linked immunosorbent assay.

Variable quantitation of Haemophilus influenzae type b anticapsular antibody by radioantigen binding assay

The measurement of antibody to Haemophilus influenzae type b capsular polysaccharide is important in the study of natural immunity and in the immunogenicity evaluation of H. influenzae type b vaccines. Several radioantigen binding assays (RABA) have been developed to measure H. influenzae type b anticapsular antibody, but recent immunogenicity data obtained with structurally similar vaccines suggest major differences in antibody quantitation in different laboratories. To evaluate interlaboratory variability in the measurement of anticapsular antibody levels, we blindly evaluated a sample of 40 pre- and postimmunization sera by eight RABAs in different laboratories. Evaluation of RABA methods revealed differences in polysaccharide antigens, radiolabeling methods, concentration and volume of antigen and antibody, and other assay methods. The reported results of assays varied significantly between laboratories (up to sixfold differences in geometric means), in part because of differences in assay sensitivity and different proportions of samples having undetectable levels of antibody (0 to 65% of specimens with undetectable levels). After standardizing the limit of sensitivity for all assays (0.125 microgram/ml), the results of all combinations of paired analyses of RABA assays correlated well (r = 0.88 to 0.99) but the geometric mean levels still varied as much as twofold. For individual sera, the differences between paired assays often were substantial (P less than or equal to 0.0001, paired t test), with some results varying as much as 64-fold. Differences were greatest for lower levels of antibody. There was good comparability and interlaboratory reproducibility of some assays but not of others. Intrinsic or extrinsic labeling of the antigen was not a major determinant of comparability. In most instances, the current variation in the quantitation of antibody levels by these assays precludes interassay comparisons. A standardized measurement of antibody needs to be developed to adequately compare results between different H. influenzae type b immunogenicity studies.

Correlates of therapeutic efficacy in experimental methicillin-resistant Staphylococcus aureus endocarditis

Seventy animals with experimental aortic valve endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA) were randomized to receive: no therapy; pefloxacin 40 or 80 mg/kg/day i.v.; or vancomycin 30 mg/kg/day i.v. Vancomycin caused a more rapid decrease in intravegetation MRSA counts than pefloxacin at 40 or 80 mg/kg/day (p less than 0.001, p less than 0.05, respectively, therapy day 3). The major correlate of therapeutic efficacy in this study was the significantly higher mean intravegetation levels achieved by vancomycin (16.8 +/- 6.1 micrograms/g) versus those attained by pefloxacin therapy at either 40 (1.6 +/- 0.13 micrograms/g) or 80 mg/kg/day (2.8 +/- 0.53 micrograms/g, p less than 0.005, p less than 0.025, respectively).

Influence of Staphylococcus aureus antibody on experimental endocarditis in rabbits

To evaluate the potential protective benefit of antibody to whole cells of Staphylococcal aureus for the prevention of endocarditis, the rabbit endocarditis model was used. Methicillin-sensitive (17A) and methicillin-resistant (173) S. aureus strains were evaluated in rabbits with or without indwelling intracardiac catheters. All immunized rabbits developed significant homologous agglutinating antibody titers (the mean reciprocal titers were 15,300 to strain 17A and 1,150 to strain 173). After challenge, virtually no significant differences were observed between immunized and unimmunized animals with respect to (i) incidence of endocarditis, (ii) concentration of bacteria in infected vegetations, (iii) incidence of metastatic renal abscesses, or (iv) concentrations of bacteria in infected kidneys. The clearance of homologous S. aureus strains from blood cultures was similar for immunized and unimmunized animals at 10 to 90 min after intravenous challenge. In vivo adherence of homologous S. aureus strains to aortic valves and vegetations was similar in immunized and unimmunized animals when evaluated at 30 and 90 min postchallenge. Even without catheterization, the incidence of bacteremia and renal abscesses was the same in immunized and unimmunized rabbits. Whole-cell-induced S. aureus antibody did not prevent or modify any stage in the development of endocarditis in rabbits.

Factors influencing immunogenicity and safety of two Haemophilus influenzae type b polysaccharide vaccines in children 18 and 24 months of age

The purpose of this study was to evaluate differences in the safety and immunogenicity of Haemophilus influenzae type b (Hib) capsular polysaccharide vaccine produced by two manufacturers (Connaught and Praxis) in children 18 and 24 months of age. Eighty-five children were evaluated in a prospective, double-blind, randomized fashion. Postvaccination antibody concentrations (measured by radioimmunoassay) and response rates were not significantly different between the two manufacturers' vaccines but immunogenicity was significantly less in 18-month-old children (antibody concentration, 0.149 microgram/ml) compared with 24-month-old children (0.838 microgram/ml) (P = 0.001). No significant differences were noted in the safety of the two vaccines. This study suggests that previously observed differences of immunogenicity data between various type b capsular polysaccharide vaccines are due to differences in antibody assays, not in vaccines. Eighteen-month-old children appear to have a relatively poor immune response to type b capsular polysaccharide. Therefore to optimize the benefits of immunization, we suggest children receive this vaccine at 24 months of age.