Vaccines in pregnancy

The concept of maternal immunization to prevent infectious diseases during a period of increased vulnerability in the infant is supported by historical experience and carefully conducted studies of various viral and bacterial vaccines. Candidate vaccines should be minimally reactogenic, immunogenic, and safe. Health education and access to immunization should be a priority if maternal immunization is to succeed as a disease prevention strategy. The potential effect on the incidence of disease in the newborn and young infant can only increase as more candidate vaccines that could be administered during pregnancy become available. In the future, common infections and other, more dreaded diseases, such as herpes simplex virus infection, cytomegalovirus, and human immunodeficiency virus infection, could be prevented with this intervention. Further research on the safety and efficacy of maternal immunization must continue if the occurrence of serious infectious diseases in neonates and young infants is to be reduced.

Passive immunization for the prevention of otitis media

The safety and protective efficacy of exogenously-administered immunoglobulin for the prevention of otitis media has been demonstrated in the clinical trials of the human-derived polyclonal immune globulin used to prevent Haemophilus influenzae type b disease and respiratory syncytial virus infection in high risk neonates and young children. However, this form of therapy is expensive, difficult to administer due to the requirements of slow intravenous infusion or relatively large volumes given intramuscularly, and associated with side effects related to the volume and nature of the immunoglobulin preparation. In contrast, RSV-specific monoclonal antibody has not been as successful as human-derived immunoglobulin in preventing otitis media in high risk infants. The administration of monoclonal-antibody for the prevention of otitis media will be difficult, potentially due to the need for antibody to multiple epitopes of the viral and bacterial pathogens which could be targets. The use of maternal antibody to provide passive immunity to young infants at a time when they are most vulnerable to severe sequelae of infection can also be considered. We have studied maternal immunization using either a 23-valent pneumococcal polysaccharide vaccine or a conjugate H. influenzae type b (Hib) vaccine. Significant levels of maternally-derived Hib or pneumococcal antibody were transferred from the mother to the infant at the time of birth and persisting, for some antigens, through 2 months of age. The use of maternal immunization to prevent otitis media and other respiratory complications remains to be studied, but results of these small clinical trials indicate further clinical investigation is warranted.

Predicting HIV disease progression in children using measures of neuropsychological and neurological functioning. Pediatric AIDS clinical trials 152 study team

BACKGROUND

Neuropsychological testing and 2 measures of neurological status, cortical atrophy, and motor dysfunction were assessed for their usefulness in predicting human immunodeficiency virus (HIV) disease progression in infants, children, and adolescents who participated in Pediatric AIDS Clinical Trials Group Protocol 152 (PACTG 152).

METHODS

A cohort of 722 antiretroviral therapy-naive children with symptomatic HIV infection were assessed at study entry and at later intervals. Assessments included neurodevelopmental testing, neuroradiologic imaging, and neurological examination of motor function. CD4 cell count and plasma RNA viral load also were measured.

RESULTS

Children with the lowest neuropsychological functioning (IQ < 70) at baseline had the highest risk for later HIV disease progression (56%), compared with those with borderline/low (IQ = 70-89) functioning (26%), or with average or above (IQ > 90) functioning (18%). This was also true of week 48 neuropsychological functioning. Motor dysfunction (especially reduced muscle mass) at entry also predicted disease progression. Furthermore, motor dysfunction and week 48 neuropsychological functioning provided predictive information beyond that obtainable from surrogate markers of HIV disease status (eg, CD4 count, HIV RNA level). Children with cortical atrophy also were at higher risk for later disease progression, but when CD4 count and RNA viral load were known, cortical atrophy information provided no additional predictive information.

CONCLUSIONS

Measures of neuropsychological and motor function status provide unique information regarding pediatric HIV disease progression. As such, these findings have important implications for predicting long-term outcomes (eg, longevity) in pediatric patients.

Treatment-mediated changes in human immunodeficiency virus (HIV) type 1 RNA and CD4 cell counts as predictors of weight growth failure, cognitive decline, and survival in HIV-infected children

This meta-analysis of 5 large studies of the Pediatric AIDS Clinical Trials Group was undertaken to evaluate the predictive value of antiretroviral treatment-mediated changes in 3 markers of human immunodeficiency virus (HIV) type 1 disease progression-HIV-1 RNA level, CD4 cell count, and CD4 percentage-for weight growth failure, cognitive decline, and survival in HIV-infected children. Proportional hazards models were used to assess the prognostic value of the markers at baseline and after 24 weeks of treatment, with data from 1089 children. Among children receiving nucleoside with or without nonnucleoside reverse-transcriptase inhibitors, higher immunologic and lower virologic markers at baseline and after 24 weeks were significant independent predictors of survival, whereas virologic markers were significant predictors of weight growth and cognitive failure in children >1 year old. The finding of differential age effects on pediatric-specific clinical outcomes emphasizes the need for continued investigation of treatment effects in children.

Respiratory syncytial virus in patients with congenital heart disease: a contemporary look at epidemiology and success of preoperative screening

Awareness of respiratory syncytial virus (RSV) as a serious pathogen in the child with congenital heart disease is increasing. We studied the impact of RSV lower respiratory tract disease on patients in a large academic pediatric cardiology practice. We found that RSV disease necessitating hospitalization occurs in congenital heart disease patients well into the second year of life. Although pulmonary hypertension remains a significant risk factor for morbidity in these patients, it does not appear to be as much of a factor as in the past. By implementing a nasopharyngeal RSV enzyme-linked immunoassay screening of young patients prior to cardiac surgery we found a reduction in community-acquired postoperative RSV disease. We postulate this will lead to a reduction in nosocomial disease in the postoperative care unit.

The CCR5Delta32 allele slows disease progression of human immunodeficiency virus-1-infected children receiving antiretroviral treatment

The role of the CCR5Delta32 allele in human immunodeficiency virus (HIV)-1-related disease progression was analyzed for 457 antiretroviral-naïve children who had participated in the Pediatric AIDS Clinical Trials Group 152 study, which demonstrated that didanosine (ddI) or zidovudine + ddI treatments were superior to zidovudine alone. The CCR5Delta32 allele was detected at an overall frequency of 6.1% (28/457). At study entry, heterozygote children (wild type [wt]/Delta32) had higher baseline median CD4(+) counts/mm(3) than wt/wt children had (1035 vs. 835 cells/mm(3); P=. 043), higher mean weight-for-age Z scores (-0.15 vs. -0.84; P=.01), and a trend toward less cortical atrophy (P=.059). During antiretroviral treatment and study follow-up, there was a trend toward less disease progression and death among heterozygote children than among wt/wt children (P=.056; relative hazard, 0.28; 95% confidence interval, 0.07-1.13) independent of the antiretroviral treatment to which they were randomized.

Diminution of the anti-polyribosylribitol phosphate response to a combined diphtheria-tetanus-acellular pertussis/Haemophilus influenzae type b vaccine by concurrent inactivated poliovirus vaccination

BACKGROUND

Prelicensure studies of Haemophilus influenzae type b vaccines (Hib) and diphtheria-tetanus-acellular pertussis vaccines (DTaP) were evaluated with concurrent oral poliovirus vaccine (OPV). However, inactivated poliovirus vaccine (IPV) is now recommended. A trial was conducted in which infants received a DTaP and Hib vaccine, separately (+) or combined (/), with either all OPV, all IPV or sequential IPV-OPV for the primary series of vaccinations.

METHODS

In this protocol 567 infants were equally randomized to receive one of the following: Reference Arm A, DTaP + Hib + OPV; Treatment Arm B, DTaP/Hib + OPV; Treatment Arm C, DTaP/Hib + IPV at 2 and 4 months and OPV at 6 months; or Treatment Arm D, DTaP/Hib + IPV. antibodies against all administered antigens were measured at 7 months of age. Children with an antibody response to Hib (anti-polyribosylribitol phosphate (anti-PRP) <0.15 microg/ml had an antibody titer repeated after the toddler booster immunization.

RESULTS

A significant diminution in the anti-PRP response was observed at 7 months of age in children given two or three doses of IPV concurrently with DTaP/Hib, compared with the groups given OPV. The geometric mean concentration of anti-PRP, percentage of children with > or = 0.15 microg/ml and percentage of children with > or = 1.0 microg/ ml, respectively, were: A, 4.4, 98%, 81%; B, 3.2, 94%, 78%; C, 1.3, 86%, 58% and D, 1.2, 84%, 53%.

CONCLUSION

In this trial concurrent IPV appeared to interfere with the anti-PRP response to DTaP/Hib vaccine, suggesting that introduction of new vaccines may require evaluation of immune responses to all concurrently administered vaccines.

A step ahead. Infant protection through maternal immunization

The concept of maternal immunization to prevent infectious diseases during a period of increased vulnerability in infants is not new and is supported by historical experience and carefully conducted studies of various viral and bacterial vaccines. Candidate vaccines should be minimally reactogenic, immunogenic, and safe for maternal immunization to be considered as a disease prevention strategy. The possibilities increase as more potential candidate vaccines for use during pregnancy become available, including conjugate meningococcal vaccines, parainfluenza virus type 3 purified subunit vaccines, herpes simplex virus, cytomegalovirus, and HIV vaccines. Additional research on the safety and efficacy of maternal immunization must continue to effect the development of infectious diseases in neonates and infants.

Safety and immunogenicity of six acellular pertussis vaccines and one whole-cell pertussis vaccine given as a fifth dose in four- to six-year-old children

OBJECTIVE

To evaluate the safety and immunogenicity of 6 different acellular pertussis vaccines combined with diphtheria and tetanus toxoids (DTaP) and with 1 licensed whole-cell pertussis vaccine (DTwP) as a fifth dose in children who had previously received the same DTaP, a different DTaP, or DTwP as primary and fourth-dose vaccinations.

METHODS

Healthy 4- to 6-year-old children were enrolled at 5 National Institute of Allergy and Infectious Diseases Vaccine Treatment and Evaluation Units to receive a fifth dose of a DTaP or DTwP vaccine. All had been randomly assigned to receive 3 primary doses of DTaP or DTwP at 2, 4, and 6 months and a fourth-dose booster at 15 to 20 months of age as part of earlier National Institutes of Health multicenter acellular pertussis vaccine trials. Parents recorded the occurrence and magnitude of fever, irritability, and injection site redness, swelling, and pain for 3 days after vaccination. Sera obtained before and 1 month after the booster vaccination were analyzed by enzyme-linked immunosorbent assay for antibody to pertussis toxin, filamentous hemagglutinin, fimbriae, pertactin, and diphtheria and tetanus toxoid. Safety and/or immunogenicity data are reported for 317 children who received DTaP and 10 children who received DTwP.

RESULTS

Fever and moderate or severe irritability were uncommon following the fifth dose of DTaP vaccine and were generally less frequent than following the fourth dose. However, for the DTaP vaccine groups, redness, swelling, and pain increased in prevalence compared with the fourth dose. The time course and frequency of reactions following DTaP vaccination were generally similar in children who received the same DTaP, a different DTaP, or DTwP for previous doses in the 5- dose series. No significant differences among the DTaP vaccines were detected in the occurrence of reactions, but the statistical power to detect differences was limited by sample size. Significant increases in antibodies directed against the included antigens were observed for all DTaP vaccines in paired pre- and post-fifth dose sera. Post-fifth dose antibody concentrations differed significantly among the DTaP vaccines. Some children in the study showed an antibody response to an antigen not reported to be in the DTaP vaccine.

CONCLUSION

All the studied DTaP vaccines performed similarly with regard to reactions, whether given as a fifth sequential dose of the same vaccine, a mix of different DTaP vaccines in the 5-dose sequence, or after 3 DTwP and 1 DTaP vaccinations. Large injection site reactions occurred more frequently after the fifth dose of DTaP than after the previous 4 doses. A fifth dose of all DTaP vaccines induced an antibody response to those antigens contained in the vaccine. No DTaP was consistently most or least reactogenic or immunogenic.

Extensive swelling after booster doses of acellular pertussis-tetanus-diphtheria vaccines

BACKGROUND

Diphtheria and tetanus toxoid combined with acellular pertussis (DTaP) vaccines are less reactogenic than diphtheria and tetanus toxoid combined with whole cell pertussis (DTwP) vaccines. However, local reactions increase in rate and severity with each successive DTaP dose, and swelling of the entire injected limb has been reported after booster doses.

METHODS

We reviewed reports of swelling of the entire thigh or upper arm after the fourth and fifth dose, respectively, of DTaP vaccines administered in the National Institutes of Health multicenter comparative DTaP studies. Relationships were explored among reports of severe swelling, rates of other reactions, quantity of vaccine contents, and prevaccination and postvaccination antibody levels to pertussis toxin, tetanus toxin, and diphtheria toxin.

RESULTS

Entire thigh swelling was an unsolicited reaction reported in 20 (2%) of the 1015 children who received 4 consecutive doses of the same DTaP vaccine. The reaction was associated with 9 of the 12 DTaP vaccines evaluated. Although there were no reports of swelling of the entire upper arm in 121 children given a fifth dose of the same DTaP, 4 (2.7%) of 146 recipients of 5 doses of a mixed schedule of DTaP vaccines experienced such swelling. Rates of other reactions were higher in children with entire thigh swelling than in those without. Of the children with entire thigh swelling, 60% had local pain, and 60% had erythema. All swelling subsided spontaneously without sequelae. There was a significant linear association between the rates of entire thigh swelling after dose 4 and diphtheria toxoid content in the DTaP products. Lesser degrees of swelling (>50 mm but less than entire limb) correlated with pertussis toxoid content after dose 4 and aluminum content after dose 5. No relationship was established between levels of serum antibody to diphtheria, tetanus, or pertussis toxin and rates of swelling of the whole thigh.

CONCLUSIONS

Booster doses of DTaP vaccines can cause entire limb swelling, which is usually associated with redness and pain. Our data suggest that this extensive swelling reaction may be more common with vaccines containing high diphtheria toxoid content.

Neurologic, neurocognitive, and brain growth outcomes in human immunodeficiency virus-infected children receiving different nucleoside antiretroviral regimens. Pediatric AIDS Clinical Trials Group 152 Study Team

OBJECTIVES

To compare the impact of three different nucleoside reverse transcriptase inhibitor regimens, zidovudine (ZDV) monotherapy, didanosine (ddI) monotherapy, and ZDV plus ddI combination therapy, on central nervous system (CNS) outcomes in symptomatic human immunodeficiency virus (HIV)-infected children.

METHODS

Serial neurologic examinations, neurocognitive tests, and brain growth assessments (head circumference measurements and head computed tomography or magnetic resonance imaging studies) were performed in 831 infants and children who participated in a randomized double-blind clinical trial of nucleoside reverse transcriptase inhibitors. The Pediatric AIDS Clinical Trials Group study 152 conducted between 1991 and 1995 enrolled antiretroviral therapy-naive children. Subjects were stratified by age (3 to <30 months of age or 30 months to 18 years of age) and randomized in equal proportions to the three treatment groups.

RESULTS

Combination ZDV and ddI therapy was superior to either ZDV or ddI monotherapy for most of the CNS outcomes evaluated. Treatment differences were observed within both age strata. ZDV monotherapy showed a modest statistically significant improvement in cognitive performance compared with ddI monotherapy during the initial 24 weeks, but for subsequent protection against CNS deterioration no clear difference was observed between the two monotherapy arms.

CONCLUSIONS

Combination therapy with ZDV and ddI was more effective than either of the two monotherapies against CNS manifestations of human immunodeficiency virus disease. The results of this study did not indicate a long-term beneficial effect for ZDV monotherapy compared with ddI monotherapy.

Influenza A virus outbreak in a neonatal intensive care unit

BACKGROUND

Nosocomial infections with influenza virus are rarely recognized in neonatal intensive care units (NICU). An outbreak of influenza A virus infection in the NICU of an urban county hospital during the 1997 to 1998 influenza season is reported.

METHODS

Clinical and virologic data were recorded in all symptomatic NICU patients after influenza A infection was diagnosed in one infant in October, 1997.

RESULTS

Influenza A/H3N2 was isolated from two of four symptomatic infants. The application of rapid diagnostic techniques for the characterization of influenza virus infection allowed the timely institution of basic infection control measures, limiting this outbreak. Resistance to amantadine was documented for the first time in this patient population by reverse transcription-PCR within 48 h of treatment in one case.

CONCLUSIONS

Prevention by immunization is a priority in those caring for high risk NICU patients.

Prevention strategies for respiratory syncytial virus: passive and active immunization

Prevention of respiratory syncytial virus (RSV) disease may ultimately be possible with active immunization, although no vaccine is currently available. Formalin-inactivated RSV vaccine caused serious disease in some recipients re-exposed to RSV, which slowed vaccine development. Current RSV vaccine candidates include RSV fusion protein vaccines, chimeric fusion protein-glycoprotein vaccines, and various live, attenuated RSV vaccines. RSV vaccines may be problematic in very young infants and newborns because of the relatively poor immunogenicity of most vaccine candidates to date. Passive immunization with human polyclonal intravenous immune globulin and humanized monoclonal antibody directed against the conserved fusion protein of RSV prevents severe RSV disease, although not necessarily viral infection. The humanized RSV monoclonal antibody is licensed for use in premature infants and infants with bronchopulmonary dysplasia and is being evaluated in infants with cardiac disease. Another innovative approach to prevent RSV disease in young infants is maternal immunization with a vaccine such as the purified fusion protein vaccine. Such a vaccine could stimulate antibody response to RSV surface glycoproteins and potentially prevent RSV disease in the mother, while maternal antibodies produced could be passively transmitted across the placenta to the infant. A pilot study in postpartum women demonstrated immunogenicity with no significant adverse reactions.

Respiratory system mechanics in patients receiving aerosolized ribavirin during mechanical ventilation for suspected respiratory syncytial viral infection

Respiratory syncytial virus (RSV) is an important respiratory pathogen for infants. Aerosolized ribavirin (AR) has been used in mechanically ventilated (MV) patients with RSV bronchiolitis. The purpose of this study was to measure respiratory system mechanics (RSM) in pediatric patients requiring MV and receiving AR for suspected RSV. Patients were prospectively randomized to receive AR, either at a regular dose (RD) (6 g/300 mL over 18 hr/day) or a high dose (HD) (6 g/100 mL over 2 hr, three times a day). To measure changes in RSM, a passive exhalation technique was used before and after each dose of AR; time constant (tc) in s, resistance (Rrs) in cmH(2)O/mL/kg/s, and quasistatic compliance (Crs) in mL/cmH(2)O/kg were measured. Airway pressure and flow signals were obtained and analyzed using a pneumotachograph, a differential pressure transducer, and a computer interface. Statistical analysis was done by Mann-Whitney and Wilcoxon rank tests. Thirteen patients were enrolled: 5 patients in the HD group (mean age of 52 months), and 8 patients in the RD group (mean age of 10 months). Four and 5 patients were positive for RSV by ELISA in the HD and RD groups, respectively. The RSM in the HD group were: tc, 0.58 +/- 0.15 s and 0.55 +/- 0.20 s before and after AR, respectively; Rrs, 0.03 +/- 0. 03 cmH(2)0/mL/kg/s and 0.02 +/- 0.02 cmH(2)0/mL/kg/s, respectively; and Crs, 0.63 +/- 0.21 mL/cmH(2)O/kg and 0.70 +/- 0.13 mL/cmH(2)O/kg, respectively. In the RD group, the RSM were: tc, 0.37 +/- 0.12 s and 0.31 +/- 0.10 s before and after AR, respectively; Rrs, 0.03 +/- 0.02 cmH(2)0/mL/kg/s and 0.02 +/- 0.01 cmH(2)0/mL/kg/s, respectively (P < 0.05); and Crs, 0.46 +/- 0.20 mL/cmH(2)O/kg and 0.46 +/- 0.19 mL/cmH(2)O/kg, respectively. We conclude that the use of AR for bronchiolitis in infants and young children during mechanical ventilation does not worsen RSM.

A randomized clinical trial of acellular pertussis vaccines in healthy adults: dose-response comparisons of 5 vaccines and implications for booster immunization

The safety and immunogenicity of 5 acellular pertussis vaccines (ACVs) were compared in a multicenter, randomized, double-blind trial. A total of 481 healthy adults were given a single intramuscular booster dose of ACV or placebo. Three different dose levels were tested for 4 ACVs: full strength (the dose level proposed for infant immunization), one-third strength, and one-tenth strength. For 1 multicomponent vaccine, only the pertussis toxoid dose level varied. Minor injection site reactions were common and similar in frequency among vaccinated groups. Late-onset injection site reactions were seen in all ACV groups. Dose-related increases in mean antibody titers against vaccine antigens were seen after immunization with all ACVs. Antibody responses against antigens not known to be present in the vaccines were detected after immunization with 4/5 ACVs. Antibody levels fell significantly during the year after immunization. These data support evaluation of ACVs for broader use among adolescents and adults.

Virologic and immunologic response to nucleoside reverse-transcriptase inhibitor therapy among human immunodeficiency virus-infected infants and children

Plasma human immunodeficiency virus RNA and CD4 lymphocyte response to nucleoside reverse-transcriptase therapy were evaluated in a large, comparative pediatric trial. Both baseline values and changes in the two laboratory markers over time correlated well with clinical outcome and possessed independent predictive value. In comparison of RNA reduction from baseline between the dideoxyinosine (ddI) and zidovudine+ddI therapeutic arms, marginal superiority of the combination arm was not correlated with an observed clinical benefit. Despite the size of this trial and the significantly higher rate of clinical end points in the zidovudine monotherapy group, attempts to establish surrogacy for plasma RNA were difficult. Nevertheless, plasma RNA and CD4 lymphocyte count together possess strong clinical predictive power and are valuable tools for both the clinician and the evaluation of new therapies.

Common emergence of amantadine- and rimantadine-resistant influenza A viruses in symptomatic immunocompromised adults

The importance and significance of amantadine- or rimantadine-resistant influenza viruses in immunocompromised patients was studied in a population of adult bone marrow transplant (BMT) recipients and patients with leukemia prospectively cultured for respiratory viruses. Influenza A viruses were isolated from 29 patients with acute respiratory illness (14 BMT recipients and 15 patients with leukemia). Fifteen patients (52%) received amantadine (n = 4) or rimantadine (n = 11) therapy. All influenza isolates recovered from six patients shedding virus for > or = 3 days were screened for antiviral susceptibility; resistant isolates were further genetically characterized. Initial influenza isolates were susceptible to amantadine or rimantadine, but subsequent isolates from five of six patients were resistant. Influenza-associated mortality was similar among patients with and without documented antiviral resistance (2 of 5 vs. 5 of 24). We conclude that development of antiviral resistance in immunocompromised individuals should be considered when they have been treated with antivirals and have shed influenza virus for a prolonged period. Isolation procedures should be instituted for all immunocompromised patients with influenza, both during and after therapy with amantadine or rimantadine.

Predictive value of quantitative plasma HIV RNA and CD4+ lymphocyte count in HIV-infected infants and children

CONTEXT

Pediatric human immunodeficiency virus (HIV) infection has unique viral pathogenetic features that preclude routine extrapolation from adult studies and require specific analysis.

OBJECTIVES

To evaluate the prognostic value of 2 key laboratory markers-plasma RNA and CD4+ lymphocyte count-for HIV disease progression in infants and children and to establish targeted values for optimal outcome.

DESIGN

Data from a cohort of 566 infants and children who participated in a randomized, placebo-controlled trial of nucleoside reverse transcriptase inhibitors (ACTG 152) were analyzed. The trial was conducted between 1991 and 1995 and enrolled a heterogeneous cohort of antiretroviral therapy-naive children (age, 3 months to 18 years); patients had a median follow-up of 32 months.

MAIN OUTCOME MEASURES

The trial clinical end points consisted of time to first HIV disease progression (growth failure, decline in neurologic or neurodevelopmental function, opportunistic infections) or death.

RESULTS

Baseline plasma RNA levels were high (age group medians, 5 x 10(4) to >10(6) copies/mL), and both baseline RNA and CD4+ lymphocyte count were independently predictive of subsequent clinical course. Risk reduction for disease progression between 49% and 64% was observed for each log10 reduction in baseline RNA and was linear without suggestion of a threshold or age effect. Disease progression predictive power was enhanced by the combined use of plasma RNA and CD4+ cell count. Marker values of less than 10000 copies/mL for plasma RNA and greater than 500 x 10(6)/L (<6.5 years of age) or greater than 200 x 10(6)/L (>6.5 years) for CD4+ cell count were associated with a 2-year disease progression rate of less than 5%.

CONCLUSIONS

Two key laboratory markers--plasma RNA and CD4+ lymphocyte count-are independent predictors of clinical course among HIV-infected infants and children. The linear, age-independent relationship between log10 plasma RNA and relative risk of disease progression strongly supports therapeutic efforts to achieve plasma virus levels as low as possible.

Haemophilus influenzae type b-specific antibody in infants after maternal immunization

OBJECTIVE

To study the kinetics of Haemophilus influenzae type b (Hib)-specific antibody in infants born to mothers immunized with an Hib polysaccharide or one of two Hib conjugate vaccines.

STUDY DESIGN

Serum antibody to the polyribosylribitol (PRP) moiety of Hib was measured by radioimmunoassay and enzyme-linked immunosorbent assay at birth and at 2 and 6 months of age in infants born to women immunized with Hib polysaccharide or conjugate vaccine (PRP-D and HbOC). A subset of infants > or = 6 months of age was immunized with Hib conjugate vaccine after licensure of this vaccine for infants. A comparison group of 18 infants born to unimmunized women received the same Hib conjugate vaccine on a similar schedule.

RESULTS

Total PRP antibody concentrations were 1.50, 14.4 and 20.4 microg/ml in 2-month-old infants born to mothers immunized with polysaccharide, PRP-D and HbOC vaccines, respectively, and 2.54, 1.35 and 2.46 microg/ml in 6-month-old infants. Infants born to mothers immunized with polysaccharide vaccine had significantly less PRP antibody at 2 months of age but similar antibody concentrations at 6 months of age. Persistence or increases in total PRP antibody during 6 months were noted in 21 of 47 (44.6%) study infants. A subset of study and comparison infants was immunized with a mean of 2.6 doses of Hib vaccines between 6 months and 2 years of age, and all infants had total PRP antibody concentrations > or = 0.15 microg/ml.

CONCLUSION

Conjugate Hib vaccines administered during the last trimester of pregnancy resulted in significantly higher PRP antibody titers in infants at birth and 2 months of age than did polysaccharide vaccine. A subset of infants born to immunized mothers was subsequently immunized with Hib conjugate vaccine and had antibody concentrations similar to those in infants born to nonimmunized women.

A safety and immunogenicity comparison of 12 acellular pertussis vaccines and one whole-cell pertussis vaccine given as a fourth dose in 15- to 20-month-old children

OBJECTIVE

To compare the safety and immunogenicity of 12 different acellular pertussis vaccines combined with diphtheria and tetanus toxoids (DTaP) with one licensed diphtheria, tetanus, and whole-cell pertussis vaccine (DTwP) as a fourth-dose booster in children who had previously received DTaP or DTwP primary vaccinations.

METHODS

Healthy 15- to 20-month-old children were enrolled at six National Institutes of Health Vaccine Treatment and Evaluation Units. All had been randomly assigned to receive three primary doses of DTaP or DTwP at 2, 4, and 6 months of age as part of an earlier National Institutes of Health multicenter trial of DTaP vaccines in the same Vaccine Treatment and Evaluation Units. Parents recorded the occurrence and magnitude of fever; irritability; and injection site redness, swelling, and pain for 3 days after vaccination. Sera obtained before and 1 month after the booster vaccination were analyzed for antibody to pertussis toxin (PT), filamentous hemagglutinin (FHA), fimbriae (FIM), and pertactin (PRN). Diphtheria and tetanus toxoid as well as PT neutralizing (Chinese hamster ovary cell) and whole-cell agglutinating antibodies were measured on a subset of sera.

RESULTS

A total of 1293 children contributed fourth-dose reaction data. Reactions were less frequent after DTaP than after DTwP. For children vaccinated with a fourth dose of DTaP, which was the same DTaP as received in the primary series, fever and injection site redness, swelling, and pain increased in prevalence compared with the third dose in the primary series. For children receiving DTaP as a fourth dose, injection site redness and swelling occurred more frequently in DTaP-primed than in DTwP-primed children. Variation in the occurrence of reactions among DTaP vaccines was observed. A total of 1160 paired pre- and postvaccination sera were available for analysis. Serum antibody concentrations before boosting were lower than those obtained 1 month after the primary immunization. After the fourth dose, significant increases in antibodies directed against the included antigens were observed for all vaccines; postbooster vaccination antibody titers differed significantly among the DTaP vaccines. For children primed and boosted with the same DTaP, antibody levels were not directly related to the quantity of antigen included for PT, FHA, and FIM; for PRN, there was a closer relationship. Some DTaP vaccines given as fourth-dose boosters elicited antibody to PRN or FIM in some vaccinees, although the DTaP vaccines were not reported to contain these antigens; these responses were observed more frequently in DTwP-primed children. Agglutinin antibody rises were observed in all groups immunized with four doses of a DTaP vaccine containing FHA or PRN, regardless of whether the vaccine included FIM. Diphtheria and tetanus antibody levels exceeded the presumed protective concentration (0.1 IU/mL for diphtheria and 0.01 IU/mL for tetanus) after the fourth dose for all vaccinees.

CONCLUSION

Although differences were observed in reaction rates among the DTaP vaccines given as a fourth dose, the DTaP vaccines were, in general, associated with fewer adverse events than a US-licensed DTwP. For DTaP vaccines, fever; irritability; and injection site pain, redness, and swelling occurred more frequently after the fourth dose than after the third dose of the same vaccine in the primary series. No DTaP was consistently most or least reactogenic or immunogenic. Although serologic correlates of pertussis immunity are not defined, it is clear that most DTaP vaccines can stimulate comparable or higher serum antibody responses than DTwP for those antigens contained in the vaccine.

Zidovudine, didanosine, or both as the initial treatment for symptomatic HIV-infected children. AIDS Clinical Trials Group (ACTG) Study 152 Team

BACKGROUND

Zidovudine has been the drug of choice for the initial treatment of symptomatic children infected with the human immunodeficiency virus (HIV). This trial was designed to assess the efficacy and safety of treatment with zidovudine alone as compared with either didanosine alone or combination therapy with zidovudine plus didanosine.

METHODS

In this multicenter, double-blind study, symptomatic HIV-infected children 3 months through 18 years of age were stratified according to age (<30 months or > or =30 months) and randomly assigned to receive zidovudine, didanosine, or zidovudine plus didanosine. The primary end point was length of time to death or to progression of HIV disease.

RESULTS

Of the 831 children who could be evaluated, 92 percent had never received antiretroviral therapy and 90 percent had acquired HIV perinatally. An interim analysis (median follow-up, 23 months) showed a significantly higher risk of HIV-disease progression or death in patients receiving zidovudine alone than in those receiving combination therapy (relative risk, 0.61; 95 percent confidence interval, 0.42 to 0.88; P=0.007). The study arm with zidovudine alone was stopped and unblinded; the other two treatment arms were continued. At the end of the study, didanosine alone had an efficacy similar to that of zidovudine plus didanosine (median follow-up, 32 months) (relative risk of disease progression or death, 0.98; 95 percent confidence interval, 0.70 to 1.37; P=0.91). A significantly lower risk of anemia or neutropenia was seen in patients receiving didanosine alone (P=0.036).

CONCLUSIONS

In symptomatic HIV-infected children, treatment with either didanosine alone or zidovudine plus didanosine was more effective than treatment with zidovudine alone. The efficacy of didanosine alone was similar to that of the combination therapy and was associated with less hematologic toxicity.

Respiratory viral infections in immunocompetent and immunocompromised persons

The acute respiratory illnesses are the most common type of acute illness in the United States today. The respiratory viruses--which include influenza viruses, parainfluenza viruses, respiratory syncytial virus (RSV), rhinoviruses, coronaviruses, and adenoviruses--cause the majority of these illnesses. Some of these viruses cause illness throughout the year, whereas others are most common in winter. All population groups experience these infections and illnesses. As the number of elderly persons and those with underlying disease increases, awareness is growing that these common infections can have serious consequences. This has recently been emphasized for immunocompromised persons. At the M.D. Anderson Cancer Center (MDACC), infection surveillance of mostly hospitalized adults with leukemia or a recent bone marrow transplant yielded a respiratory virus from 181 of 668 (27.1%) respiratory illness episodes. In descending order of frequency, infections with RSV, rhinoviruses, influenza viruses, parainfluenza viruses, and adenoviruses were detected in each of three surveillance years. High frequencies of nosocomial acquisition occurred, as has been noted in prior reports. Similarly, persistence of infection and high frequencies of pneumonia and death among infected patients occurred, which have also been noted earlier. At MDACC, pneumonia occurred in 58-78% of infected patients, and 22-44% died. The role of the virus infection in many cases of pneumonia is uncertain, but death from pure viral pneumonia is well documented. A number of immune deficiencies in this patient population and options for control of these infections have been described that can, respectively, account for the medical problem and provide ways to approach prevention and treatment.

Prevention and treatment of respiratory syncytial virus and parainfluenza viruses in immunocompromised patients

Immunocompromised patients are vulnerable to severe infections due to respiratory syncytial virus (RSV) and parainfluenza viruses (PIV), and therefore prevention and treatment strategies must be considered. The prevention of RSV disease with high-titer RSV-specific immune globulin has been documented in very young children but has not been systematically studied in high-risk adults. Vaccines against RSV and PIV are under development, but their use in immunocompromised patients is problematic. Ribavirin aerosol therapy is licensed for the treatment of RSV in pediatric patients and has also been used to treat RSV disease in adults and PIV disease in severely immunocompromised children and adults. Uncontrolled trials show that early therapy with ribavirin aerosol may be beneficial, but treatment of pneumonia in patients with respiratory failure is rarely successful. Other potential treatments for RSV or PIV disease include high-dose, short-duration ribavirin therapy; combined immunoglobulin and ribavirin therapy; polyclonal and monoclonal antibodies; and, potentially, immunomodulators.

Community respiratory virus infections in immunocompromised patients with cancer

Community respiratory viruses, such as respiratory syncytial virus (RSV), influenza viruses, parainfluenza viruses, adenoviruses, and picornaviruses, are an important cause of respiratory disease in the immunocompromised adult with cancer. Recent studies have demonstrated that a minimum of 31% of adult bone marrow transplant (BMT) recipients and 18% of adults with leukemia who are hospitalized with an acute respiratory illness have a community respiratory virus infection. The temporal occurrence of these infections in immunocompromised patients tends to mirror their occurrence in the community. The clinical illnesses range from self-limited upper respiratory illnesses to fatal pneumonias, depending on the type of virus and the type and degree of immunosuppression. The pneumonias may be viral, bacterial/fungal, or mixed. The highest frequency of progression to fatal viral pneumonia has been reported for RSV infections in recently transplanted BMT recipients and myelosuppressed patients with leukemia. Studies have suggested that early therapy for RSV pneumonia with a combination of aerosolized ribavirin and intravenous immunoglobulin may be of benefit. Defining effective prophylactic and therapeutic strategies will be a challenge, given the diversity of viruses, the wide spectrum of immunocompromised patients with varying vulnerability to serious community respiratory virus disease, and the frequent presence of other opportunistic infections and medical problems. A combination of antiviral drugs and immunotherapy may need to be considered for their potential additive effect as well as to prevent the emergence of resistant virus, as occurs during monotherapy for influenza with amantadine or rimantadine. The optimal therapies need to be defined in controlled trials; however, it appears that a favorable response will hinge on the initiation of therapy at an early stage of the respiratory illness.

Clinical and laboratory characteristics of a large cohort of symptomatic, human immunodeficiency virus-infected infants and children. AIDS Clinical Trials Group Protocol 152 Study Team

BACKGROUND

A large cohort of antiretroviral therapy-naive, symptomatic, HIV-infected children were enrolled into a controlled therapeutic trial (AIDS Clinical Trials Group Protocol 152), providing an opportunity to describe their clinical and laboratory characteristics and determine age-related distinctions.

METHODS

Study entry evaluations for 838 of 839 enrolled children were analyzed. Weight, head circumference (if < 30 months of age), neuroradiologic imaging of the head, developmental or cognitive status and neurologic examination were assessed. Laboratory studies included hemoglobin, absolute neutrophil count, CD4 cell count, serum amylase, alanine aminotransaminase, p24 antigen and HIV blood culture. Data were categorized by age (3 to < 12 months, 12 to < 30 months, 30 months to 6 years and > or = 6 years).

RESULTS

Younger children had significantly higher rates of abnormalities before antiretroviral therapy, especially factors relating to growth and neurologic or cognitive function. Lower CD4+ cell counts and percentages as well as a positive serum p24 antigen correlated with lower weight-for-age Z scores and developmental indices.

CONCLUSIONS

These data provide a description of the clinical characteristics of HIV-infected US children at the time antiretroviral therapy is initiated for HIV-related symptoms. The high rate of abnormalities of growth, development and cognitive ability that were observed in children < 30 months of age demonstrates that treatment strategies should be developed for earlier intervention.

Association of placental transfer of anti-Haemophilus influenzae type b polysaccharide antibodies with their V regions

Immunization of mothers during pregnancy may be an effective means of providing protection to infants during the first months of life against many pathogens. Previous studies have identified factors that influence the transfer of immunoglobulin across the placenta, including the time of vaccination during pregnancy and isotypes of specific immunoglobulins. By studying antibodies to Haemophilus influenzae type b polysaccharide (Hib-PS) in 26 pairs of maternal-cord sera obtained from unimmunized healthy women and 22 pairs of maternal-cord sera from women immunized with one of three different Hib vaccines, we have found that the immunoglobulin transfer is also dependent on the V region of antibodies. Anti-Hib-PS derived from the V kappa II gene "A2" was transferred about ten times more efficiently to the fetus than other anti-Hib-PS antibodies (20% vs 1-2%). It was found that antibodies derived from the A2 V kappa gene are primarily IgG whereas other antibodies are preferentially associated with the IgM isotype. The potential association between the antibody V region with preferential placental transfer should be considered for future studies involving maternal immunization.

Rapid diagnosis of respiratory syncytial virus infections in immunocompromised adults

Although rapid antigen detection methods for the documentation of respiratory syncytial virus (RSV) infections are widely used with pediatric patients, these tests have not been prospectively evaluated in immunocompromised (IC) adults. For bone marrow transplant recipients and adult patients undergoing chemotherapy for leukemia who had recent onset of respiratory symptoms, respiratory samples (combined nasal wash [NW]-throat swab [TS], endotracheal tube [ET] aspirate, or bronchoalveolar lavage [BAL] samples) were collected for simultaneous culture and rapid antigen detection with the Directigen test kit (Becton Dickinson, Cockeysville, Md.). NW specimens from hospitalized pediatric patients with suspected RSV infection were also evaluated. Viral quantitation was performed on aliquots of the original specimens. A total of 539 samples from 372 adult patients were evaluated. RSV was isolated from 56 specimens (40 NW-TS, 7 ET aspirate, and 9 BAL specimens). By using culture as the "gold standard," rapid antigen detection had a sensitivity of 15% for adult NW-TS specimens, 71.4% for ET aspirate specimens, and 88.9% for BAL specimens; the specificity was > or = 97% for all specimen types. Significantly greater viral quantities were present in pediatric NW specimens than in adult NW specimens. In adults, more virus was present in BAL and ET aspirate specimens than in NW-TS specimens. Rapid detection of antigen respiratory samples obtained from the lower respiratory tracts of IC adults is sensitive and specific, but detection in upper respiratory tract samples is insensitive. The lower sensitivity of antigen detection in NW-TS specimens may be due to decreased viral load. A BAL specimen is more sensitive than an NW-TS specimen for the rapid diagnosis of RSV disease in IC adults.

Community respiratory virus infections among hospitalized adult bone marrow transplant recipients

From 1 November 1992 through 1 May 1993 and from 1 November 1993 through 1 May 1994, we conducted a prospective surveillance study at the University of Texas M.D. Anderson Cancer Center (Houston) to evaluate the role of community respiratory virus infections in hospitalized adult bone marrow transplant (BMT) recipients, Respiratory secretions were obtained from all adult BMT recipients with acute respiratory illnesses. During these two winters, a community respiratory virus was isolated from 37 (36%) of 102 patients and 30 (26%) of 115 patients, respectively. Approximately half (49%) of these infections were due to respiratory syncytial virus (RSV); the remainder were due to influenza virus (18%), picornaviruses (18%), parainfluenza virus (9%), or adenovirus (6%). Fifty-eight percent of these infections were complicated by pneumonia, with an associated mortality of 51%. The pneumonias that complicated RSV infection were almost exclusively viral in origin and were associated with a mortality of 100% if not treated promptly with antiviral agents. In contrast, many of the pneumonias that complicated the other viral infections, such as influenza, appeared to be either self-limited viral pneumonias or secondary bacterial or fungal pneumonias. Community respiratory viruses are frequent causes of acute respiratory illnesses in adult BMT recipients hospitalized during the winter and are associated with substantial morbidity and mortality.

Effect of gender, race, and parental education on immunogenicity and reported reactogenicity of acellular and whole-cell pertussis vaccines

OBJECTIVE

To determine whether gender, race (black or white), or level of parental education influenced serologic responses or reporting of clinical reactions after immunization with acellular (DTaP) or whole-cell (DTP) pertussis vaccine with diphtheria and tetanus toxoids combined.

METHODS

Healthy infants were prospectively randomized to receive one of 13 DTaP, Lederle DTP, or another DTP. Parents recorded the occurrence of adverse reactions for 2 weeks after each inoculation. Sera obtained before the first immunization and 1 month after the third immunization were analyzed for antibody to pertussis toxin, filamentous hemagglutinin, fimbriae, and pertactin (PRN). Chinese hamster ovary cell pertussis toxin neutralization assays were performed, and levels of agglutinating antibodies determined.

RESULTS

Prevaccination antibody levels did not differ by race, gender, or parental education. Postimmunization geometric mean titers (GMTs) were strongly and consistently associated with race. For both DTaP and DTP and for every included antigen, postimmunization GMTs were about twice as high for black as for white infants. Among DTaP recipients, these differences were significant for pertussis toxin, Chinese hamster ovary cell pertussis toxin neutralization assay, filamentous hemagglutinin, PRN, and agglutinins; among the much smaller sample of WCL recipients, the differences achieved or approached statistical significance for agglutinins, PRN, and fimbriae. These findings were confirmed by regression analyses that controlled for gender, parental education, study site, and preimmunization antibody level. Reported reactions were not correlated with parental education level and showed no material correlation with gender. Black infants were reported to have had more pain than white infants after receiving WCL and DTaP and were reported to be more fussy after receiving WCL.

CONCLUSIONS

The consistently higher postimmunization GMTs among black infants seems to be a real finding for which we have no explanation; the infants did not significantly differ by race in vaccine assignment, preimmunization antibody levels, age at immunization, or interval from immunization to phlebotomy. These observations should be confirmed and further evaluated in future pertussis vaccine trials. Reported differences by race in pain and fussiness after receiving WCL might reflect chance, differences by race in the occurrence of reactions, or differences by race in the reporting of reactions.

The effect of maternal antibody on the serologic response and the incidence of adverse reactions after primary immunization with acellular and whole-cell pertussis vaccines combined with diphtheria and tetanus toxoids

OBJECTIVE

To evaluate the effect of maternally derived antibody on the immunogenicity and reactogenicity of acellular (DTaP) or whole-cell (DTP) pertussis vaccine with diphtheria and tetanus toxoids combined.

METHODS

A total of 2342 infants were randomized to receive one of 13 DTaP or 2 DTP vaccines at 2, 4, and 6 months of age. The correlation between preimmunization and postimmunization antibody after three doses of vaccine and the relation between preimmunization antibody and adverse reactions after the first immunization were modeled by linear regression.

RESULTS

After DTP but not DTaP, higher levels of preexisting antibody were associated with substantial (28% to 56%) reductions in the subsequent antibody response to pertussis toxin (PT). For other pertussis antibodies, modest inverse correlations were seen between preexisting antibody concentrations and most postimmunization antibody responses (resulting in 8% to 18% reductions in postimmunization antibody) for both DTP and DTaP. There was no consistent association in any DTP or DTaP group between adverse reactions and preimmunization antibody levels.

CONCLUSION

The PT antibody response to DTaP, unlike DTP, is not adversely affected by preexisting antibody to PT. Inhibitory effects with respect to other antibodies, seen with both DTP and DTaP, were relatively modest. Our data suggest that the use of acellular pertussis vaccines in adults, which could confer higher levels of antibody in women before pregnancy, would be unlikely to adversely affect pertussis antibody responses after DTaP among infants born to mothers with high antibody levels.

Comparison of 13 acellular pertussis vaccines: overview and serologic response

OBJECTIVE

To compare the immunogenicity of a licensed conventional whole-cell (WCL) and 13 diphtheria-tetanus-acellular pertussis (DTaP) vaccines that differed in source, method of manufacture, and included antigens; all vaccines included diphtheria and tetanus toxoids.

METHODS

Healthy infants were enrolled through six university-based vaccine and treatment evaluation units and were randomized to receive one of the study vaccines at 2, 4, and 6 months of age. Sera were obtained before the first immunization and 1 month after the third immunization and were analyzed for antibody to pertussis toxin (PT), filamentous hemagglutinin, fimbriae, pertactin, and diphtheria and tetanus toxins. Chinese hamster ovary cell toxin neutralization assays were performed, and levels of agglutinating antibodies were determined.

RESULTS

Of 2342 infants enrolled, 1942 contributed usable preimmunization and postimmunization serum specimens. Each vaccine produced significant increases in antibodies directed against the included antigens; postimmunization antibody titers differed significantly among the DTaP vaccines. For each evaluated antigen, the majority of DTaP vaccines produced antibody responses that equaled or exceeded those produced by WCL. For some antigens (eg, PT), mean antibody levels by vaccine correlated poorly with the quantity of antigen included in each vaccine; for others (eg., fimbriae), there was a close correlation.

CONCLUSION

Although serologic correlates of pertussis immunity are not defined, it is clear that DTaP vaccines can stimulate immune responses that exceed those of licensed whole-cell vaccine with respect to the measured antibodies. Particularly for PT, immunogenicity seems to depend on factors in addition to antigen concentration, possibly including antigen derivation and formulation. No DTaP was most or least immunogenic with respect to all included antigens.

Association of reactions after consecutive acellular or whole-cell pertussis vaccine immunizations

OBJECTIVE

To evaluate the relative frequency of adverse reactions after initial and subsequent immunizations among infants receiving primary immunization with acellular (DTaP) or whole-cell (DTP) pertussis vaccine with diphtheria and tetanus combined.

METHODS

We examined the occurrence of common reactions in 2127 infants within 48 hours after immunization at 2, 4, and 6 months with one of 13 DTaP or with Lederle DTP (WCL). Data on at least two consecutive immunizations were available for 357 WCL recipients and 1770 DTaP recipients. For these analyses, reactions evaluated included fever of 100.4 degrees F (38 degrees C) or greater, redness of 21 mm or larger, swelling of 21 mm or larger, moderate or severe pain, moderate or severe fussiness, loss of appetite, drowsiness, and vomiting.

RESULTS

With one exception, reactions were approximately 1.5 to 8 times more likely to occur in WCL recipients if the same reaction had been observed at the previous immunization (the single exception was redness after the second immunization). Both initial and repeated reactions were less likely in DTaP than in WCL recipients. As with WCL recipients, risks of repeated reactions in DTaP recipients were higher than the risks of initial reactions (from 2.5 to 24 times as high).

CONCLUSION

Reactions after a second or third immunization with either WCL or DTaP vaccine are more likely to occur in infants who had the same reaction after the preceding immunization. Absolute risks of repeated reactions tended to be lower after DTaP vaccine than after the WCL vaccine.

Combination therapy with aerosolized ribavirin and intravenous immunoglobulin for respiratory syncytial virus disease in adult bone marrow transplant recipients

Respiratory syncytial virus (RSV) infections in adult BMT recipients are frequently complicated by fatal pneumonias. Therapy of RSV pneumonia with aerosolized ribavirin alone has been reported to be associated with a 70% mortality rate. Because immune globulin therapy has been reported to be beneficial, we conducted a prospective trial of combination therapy with aerosolized ribavirin and intravenous immunoglobulin (IVIG). Aerosolized ribavirin was administered at 20 mg/ml for 18 h a day and IVIG was administered at 500 mg/kg every other day for the length of ribavirin therapy. Four lots of IVIG were chosen with RSV microneutralization Ab titers of 1:2048 to 1:8102. Between 8 January and 3 March 1993, during a community outbreak, 19 (45%) of 42 hospitalized adult BMT recipients with an acute respiratory illness were documented to have RSV disease. Two-thirds of these infections were hospital-acquired. All 19 patients presented with signs and symptoms of an upper respiratory tract illness. Sixteen patients developed pneumonia. The mortality was 22% in nine patients with pneumonia in whom therapy was initiated prior to the onset of profound respiratory failure. In contrast, the mortality was 100% in three patients with pneumonia in whom therapy was initiated within 24 h of respiratory failure requiring mechanical ventilation and in four untreated patients. We conclude that RSV may cause devastating outbreaks of severe pneumonia among hospitalized adult BMT recipients. Early diagnosis and combination therapy with ribavirin and IVIG was associated with a favorable outcome.

A randomized comparison of reactogenicity and immunogenicity of two whole-cell pertussis vaccines

OBJECTIVE

To compare prospectively the reactogenicity and immunogenicity of two licensed whole-cell pertussis vaccines.

METHODS

We conducted a prospective, randomized, double-blinded assessment of two licensed whole-cell pertussis vaccines with diphtheria and tetanus toxoids that were included in a multicenter trial evaluating 13 acellular pertussis vaccines. Infants were immunized at 2, 4, and 6 months of age with a single lot of Lederle (309 infants) or Massachusetts Public Health Biologic Laboratories (MPHBL; 94 infants) vaccine.

RESULTS

The group receiving the Lederle vaccine demonstrated significantly higher antibody titers to pertussis toxin by enzyme-linked immunosorbent assay (ELISA) and by the Chinese hamster ovary cell pertussis toxin neutralization assay, and to fimbrial antigens by ELISA, as well as higher mean agglutinin titers. In contrast, the group receiving the MPHBL vaccine demonstrated higher ELISA antibody levels to filamentous hemagglutinin and pertactin. Similar differences were observed in the proportions of vaccinees seroconverting to these antigens. Rates of systemic and local reactions were relatively low for both vaccines. Although the Lederle product had substantially lower reactogenicity in this study than previously reported for that vaccine, the MPHBL vaccine was significantly less reactogenic in nearly all clinical categories.

CONCLUSION

The two whole-cell vaccines demonstrated statistically significant differences in postimmunization antibody levels to all six evaluated pertussis antigens. Whether these statistically significant differences in antibody levels have clinical relevance is not clear. Rates of nearly all local and systemic reactions were significantly lower among the MPHBL group than the Lederle group. Licensed whole-cell diphtheria-tetanus-pertussis vaccines produced by different manufacturers cannot be assumed to be similar in reactogenicity or immunogenicity.

Defining the key parameters for comparing reactions among acellular and whole-cell pertussis vaccines

OBJECTIVE

To facilitate future vaccine reaction data collection and analysis, we sought to determine the minimum data set required to describe accurately and to compare common reactions after the administration of acellular (DTaP) or whole-cell (DTP) pertussis vaccine with diphtheria and tetanus toxoids combined.

METHODS

Thirteen DTaP and 2 DTP vaccines were studied in a multicenter trial involving 2342 infants who received a primary series of vaccinations at 2, 4, and 6 months of age. Temperature, fussiness, redness, swelling and pain at the injection site, antipyretic use, drowsiness, loss of appetite, and vomiting were evaluated. Reactions were assessed at 3 hours and (if not immunized in the evening) 6 hours after immunization, at bedtime each evening for 7 evenings, and on the 14th evening after immunization.

RESULTS

Two reaction assessment approaches were compared: (1) analysis of all reactions, regardless of the degree of severity; and (2) a condensation of the data to five key reactions (fever > 100 degrees F, moderate or more fussiness, any local redness, any local swelling, and moderate or more local pain). We found that the onset of reactions was infrequent beyond the second evening, and that collection and analysis of reaction data beyond that time did not further discriminate among the vaccines. Information regarding antipyretic use, loss of appetite, drowsiness, or vomiting did not assist in differentiating among these vaccines.

CONCLUSION

Monitoring the occurrence of fever greater than 100 degrees F, moderate or severe fussiness, injection site redness or swelling, and moderate or severe injection site pain occurring through the second evening after immunization will provide the minimum data set needed to discriminate among DTaP and DTP vaccines with respect to the common adverse reactions.

Simultaneous administration of Haemophilus influenzae type b vaccine with acellular or whole-cell pertussis vaccine: effects on reactogenicity and immune responses to pertussis vaccines

OBJECTIVE

To evaluate the effect of simultaneous Haemophilus influenzae type b conjugate (Hib) vaccination on the safety and immunogenicity of selected acellular (DTaP) and whole-cell (DTP) pertussis vaccines with diphtheria and tetanus toxoids combined.

METHODS

Enrollment of infants into a large multicenter study of the safety and immunogenicity of 13 DTaP and 2 DTP vaccines was partially completed when the first Hib vaccine, HbOC (Haemophilus b oligosaccharide conjugate vaccine), was licensed for use in infants. Thereafter, at each immunization most infants received HbOC simultaneously with DTaP (or DTP), administered in opposite thighs. Postvaccination geometric mean titers or concentrations (GMTs) of pertussis antibodies as measured by six different assays were compared pairwise among groups of infants receiving 0, 1, 2, or 3 simultaneous HbOC immunizations. The incidence of reactions was compared between infants who received only DTaP or DTP and those who received HbOC simultaneously.

RESULTS

Comparison of postvaccination GMTs was possible among groups of infants receiving different numbers of simultaneous immunizations for 10 of the 13 DTaP and both DTP vaccines. Increased HbOC exposure had no consistent dose-response effect on antibody titers for DTaP or DTP vaccines in any assay. Significant differences between groups in postvaccination GMTs were observed with 4 DTaP vaccines in 1 to 2 assays each; the GMTs were higher with increasing HbOC exposure for 2 DTaP vaccines and lower for 2 others. There was no significant increase in reactions with simultaneous HbOC and DTaP immunization.

CONCLUSIONS

Based on these retrospective analyses, there did not seem to be an interference in pertussis immunogenicity or alteration in reactogenicity associated with the simultaneous administration of HbOC and DTaP. These findings are encouraging with respect to the development of DTaP-Hib combination vaccines.

Comparison of 13 acellular pertussis vaccines: adverse reactions

OBJECTIVE

To compare the reactogenicity of a licensed conventional whole-cell (WCL) and 13 acellular pertussis vaccines that differed in the source, manufacture, and quantity of included antigens; all vaccines included diphtheria and tetanus toxoids.

METHODS

Healthy infants were enrolled through six university-based vaccine and treatment evaluation units and were randomized to receive one of the study vaccines at 2, 4, and 6 months of age. Parents recorded the occurrence of fever, redness, swelling, pain, fussiness, drowsiness, anorexia, and use of antipyretics for 2 weeks after each inoculation; nurses interviewed parents on the third day and at each succeeding visit; long-term follow-up information was collected from parents and medical records 1 year after the third immunization.

RESULTS

Of 2200 vaccinated infants, 2189 contributed reaction data after 6375 vaccinations. For every acellular vaccine, every monitored reaction except vomiting occurred at a significantly lower frequency and severity than was seen with WCL. The groups receiving acellular pertussis vaccines differed significantly with respect to redness, swelling, pain, and vomiting, but not with respect to fussiness, antipyretic use, drowsiness, or anorexia.

CONCLUSION

Although there were differences among the acellular vaccines, none was consistently the most or least reactogenic; all were associated with substantially fewer and less severe adverse reactions than a standard commercial whole-cell vaccine. Selection of acellular vaccines for further development and for introduction into efficacy trials can give priority to assessments of immunogenicity and purity, with comparative reactogenicity a secondary consideration.

Respiratory syncytial virus pneumonia in hospitalized adult patients with leukemia

Respiratory syncytial virus (RSV) has been demonstrated to be an important cause of life-threatening pneumonia in adult bone marrow transplant recipients; however, its role in other immunocompromised adults has not been defined. We prospectively studied all adult patients with leukemia who were hospitalized at M. D. Anderson Cancer Center (Houston) during a 1-year period (November 1993 through October 1994). During a 19-week period when RSV was prevalent in the community, it was isolated from 9 (10%) of 87 patients with leukemia who developed an acute respiratory illness. In 6 (75%) of 8 patients with profound chemotherapy-induced myelosuppression, the RSV infection was complicated by pneumonia, with an 83% mortality rate. RSV appears to be an important cause of severe and often fatal pneumonia in myelosuppressed patients with leukemia.

Interchangeability of conjugated Haemophilus influenzae type b vaccines in infants

OBJECTIVE

To evaluate the safety and immunogenicity of two Haemophilus influenzae type b (Hib) conjugate vaccines when administered in serial combination. These vaccines consisted of Hib capsular polysaccharide polyribosyl-ribitol phosphate (PRP) conjugated to the meningococcal outer membrane protein (OMP) complex (PRP-OMP) and H influenzae oligosaccharide conjugated to a mutant toxin (CRM197) isolated from Corynebacterium diphtheriae (HbOC).

DESIGN

Randomized, double-blind, clinical trial evaluating five Hib vaccination regimens.

SETTING

Vaccine Treatment and Evaluation Units and affiliated private pediatric practices at Saint Louis (Mo) University, Vanderbilt University, Nashville, Tenn, and Baylor College of Medicine, Houston, Tex.

PATIENTS

A total of 497 healthy 2-month-old infants scheduled to receive routine immunization.

INTERVENTION

Participants received either PRP-OMP or HbOC given as recommended by the manufacturer, PRP-OMP at 2 and 6 months, HbOC at 2 months, then PRP-OMP at 4 and 6 months, or PRP-OMP at 2 months and then HbOC at 4 and 6 months. Unconjugated PRP was given at 15 months to evaluate priming.

RESULTS

Geometric mean antibody concentrations differed significantly among the groups following the second and third immunizations of the primary series and following booster immunization with unconjugated PRP. On each occasion, the groups receiving serial combinations of PRP-OMP and HbOC achieved mean antibody concentrations that equalled or exceeded those of the groups receiving a single product. Adverse reactions did not vary by group.

CONCLUSIONS

The studied sequential combinations of Hib vaccines were safe and at least as immunogenic as either vaccine alone.

Transplacental antibody transfer following maternal immunization with polysaccharide and conjugate Haemophilus influenzae type b vaccines

Passive transfer of antibody to infants born to women immunized during the third trimester of pregnancy with a Haemophilus influenzae type b (Hib) vaccine (PRP polysaccharide or Hib conjugates PRP-D or HbOC) was studied in 50 mothers and infants and 47 nonimmunized mother-infant pairs. Geometric mean total PRP antibody by RIA was 1.2 micrograms/mL at delivery in unimmunized women and 21, 149, and 171 micrograms/mL in women who received PRP, PRP-D, and HbOC, respectively. Mean cord PRP antibody levels were 0.29, 3.0, 17.5, and 29.3 micrograms/mL for the corresponding groups. Postimmunization and cord PRP antibody levels were higher after maternal immunization with conjugate vaccines than with PRP vaccine (P < .01). PRP IgG1 subclass was transmitted more efficiently than IgG2 (56% vs. 35%, P < .01). The proportion of anti-PRP IgG transmitted from immunized mothers to infants correlated with time between immunization and delivery. Administration of PRP conjugate vaccines to women during pregnancy resulted in higher levels of PRP antibodies in infants than did polysaccharide or no vaccine.

High-dose, short-duration ribavirin aerosol therapy compared with standard ribavirin therapy in children with suspected respiratory syncytial virus infection

Children with suspected respiratory syncytial virus infection were examined prospectively in a randomized evaluation of standard ribavirin aerosol therapy (6 gm/300 ml water for 18 hours daily) compared with high-dose, short-duration ribavirin aerosol therapy (6 gm/100 ml water given for a period of 2 hours three times a day) by means of an oxygen hood (n = 20) or a ventilator (n = 12). Viral shedding was quantitated daily; clinical observations were recorded daily by 2 physicians aware and one unaware of treatment assignments. Study characteristics evaluated at entry were not significantly different in the high-dose and the standard-dose groups. Viral titers and clinical scores decreased similarly in both groups during the study; pulmonary function test results were also similar at discharge in children not receiving mechanical ventilation. Potential complications related to aerosol therapy were noted in three patients (one hood patient who was receiving standard therapy; two patients with an endotracheal tube in place who were receiving high-dose therapy); substantial crystallization was noted in the tubing of the patients undergoing intubation and receiving high-dose therapy. Environmental sampling revealed that ribavirin was nearly undetectable near patients supported by mechanical ventilation who were receiving either form of therapy, and was significantly decreased on a daily basis in patients without an endotracheal tube who were receiving high-dose therapy compared with those receiving standard therapy. The effects of high-dose, short-duration aerosol ribavirin therapy were similar to those of standard-dose therapy in our study patients and resulted in a decreased release of ribavirin into the room of patients receiving therapy by means of an oxygen hood.

Passive protection against respiratory syncytial virus disease in infants: the role of maternal antibody

Respiratory syncytial virus (RSV) is responsible for serious respiratory disease in young infants. More than 75% of the 678 children hospitalized for RSV at Baylor-affiliated hospitals in Houston, TX, between October, 1992, and March, 1993, were 5 months of age or younger. The importance of maternal antibody in the immunity against RSV disease has been debated. More recent epidemiologic studies have demonstrated protection against RSV in babies born to mothers with high levels of neutralizing RSV antibody. The contribution of IgG fusion or F protein antibody as a correlate with immunity from disease also has been described. With the availability of purified F protein vaccines such as the purified F protein vaccines manufactured by Lederle-Praxis-Biologicals (Pearl River, NY), immunization of pregnant women with RSV surface glycoproteins to arm the newborn with high neutralizing antibody can be considered. Advantages of maternal immunization to augment naturally occurring maternal RSV antibody are that babies most at risk for infection are least responsive to vaccines, that pregnant women respond well immunologically to vaccines in general and that placental transfer of maternal IgG antibody occurs naturally during the third trimester. The safety of maternally derived antibody would likely surpass that of exogenously administered immunoglobulin as well as would have a decreased cost. Disadvantages of maternal immunization to protect infants against RSV could include the potential inhibition of the infant's response to active immunization or subsequent disease, the lack of antibody transfer in premature infants, and liability issues. Evaluation of purified F protein vaccine in postpartum women is under way.

Acellular and whole-cell pertussis vaccines as booster doses: a multicenter study

OBJECTIVE

To compare the safety and immunogenicity of a variety of acellular (AC) and whole-cell (WC) pertussis vaccines combined with diphtheria and tetanus toxoids.

METHODS

Standard enrollment and reaction forms were used at five sites, and serologic evaluation was performed at a single site. Nine AC (Massachusetts Public Health Laboratories, Biocine Sclavo recombinant pertussis toxoid [PT], Connaught/BIKEN, Lederle three-component, Biocine Sclavo recombinant three-component, SmithKline Beecham three-component, Porton three-component, Takeda-Wyeth, and Connaught multicomponent), and three WC (Connaught Laboratories, Lederle Laboratories, and Massachusetts Public Health Laboratories) were studied. All AC contained varying concentrations of PT; some vaccines also contained filamentous hemagglutinin (FHA), pertactin, and/or agglutinogens.

RESULTS

Two hundred forty children, aged 16 to 21 months and 4 to 6 years, were enrolled at five sites. Significantly less fever, redness, swelling, pain, limp, and use of pain medication were noted following AC compared with WC. Significant increases in antibody to PT were seen following all vaccines. Significant rises in FHA antibody were seen following all WC and the seven AC that contained FHA. Postbooster PT antibody levels were similar among the AC groups, regardless of the amount of PT administered (between 3.5 and 25 micrograms per dose). The dose of FHA did not affect PT antibody response. Infants primed with WC who were boosted with a monocomponent PT vaccine did not manifest a significant antibody response to FHA.

CONCLUSION

The rate of adverse reactions was not a function of the number of antigens or the antigen quantity in the acellular vaccines, and antibody responses following AC were similar or better than antibody responses following WC. These results support the further evaluation of these vaccines in a larger National Institute of Allergy and Infectious Diseases-sponsored study in infants.

Maternal immunization with influenza or tetanus toxoid vaccine for passive antibody protection in young infants

Women in the last trimester of pregnancy were given trivalent inactivated influenza virus vaccine (TIV; A/Sichuan/H3N2, A/Taiwan/H1N1, B/Victoria) or tetanus toxoid (TT). Maternal blood was drawn before immunization and at delivery (median, 5 weeks later); infant blood was obtained within 5 days of birth and 2 months later. Antibody responses to TIV and TT were determined by microneutralization assay and ELISA. T cell response was determined by lymphocyte proliferation. Maternal seroconversion to vaccine antigens was found to one or more influenza antigen in all TIV recipients and to TT in 9 of 13 TT recipients. Significantly higher IgG antibodies to maternal vaccine antigens were present in cord and infant serum. Significant blastogenic responses were seen to influenza A and B in maternal cells of TIV-immunized women but not in cord or infant lymphocytes. Maternal immunization resulted in higher infant levels of vaccine-specific IgG antibody but not in the transfer of specific T lymphocyte response(s) or production of neonatal IgM antibody.

Controlled study of a new five-component acellular pertussis vaccine in adults and young children

A new five-component acellular pertussis (AP) vaccine containing 10 micrograms of pertussis toxoid, 5 micrograms of filamentous hemagglutinin, 5 micrograms of combined agglutinogens 2 and 3, and 3 micrograms of pertactin was evaluated in adults and young children. AP vaccine was compared with saline placebo in 31 adults, and AP vaccine combined with diphtheria and tetanus toxoids (ADTP) was compared with whole cell DTP in 41 children, ages 16-20 months, who had received whole cell DTP during infancy. AP was mildly to moderately reactogenic in adults, with pain noted within 72 h and 5-8 days after immunization. ADTP was less reactogenic than DTP in children, with significantly decreased pain, redness, irritability, and fever and less use of acetaminophen reported. No late reactions were observed in any child. The multicomponent ADTP was immunogenic, with four-fold or greater antibody rises to at least four pertussis antibody assays in all 15 immunized adults. Pertussis-specific antibody responses in children who received ADTP and DTP were similar. The multicomponent ADTP vaccine is currently being studied in a National Institute of Allergy and Infectious Diseases-sponsored efficacy study in Sweden.