Otitis media at 6-monthly assessments of Australian First Nations children between ages 12-36 months: Findings from two randomised controlled trials of combined pneumococcal conjugate vaccines

OBJECTIVES

In remote communities of northern Australia, First Nations children with hearing loss are disproportionately at risk of poor school readiness and performance compared to their peers with no hearing loss. The aim of this trial is to prevent early childhood persisting otitis media (OM), associated hearing loss and developmental delay. To achieve this, we designed a mixed pneumococcal conjugate vaccine (PCV) schedule that could maximise immunogenicity and thereby prevent bacterial otitis media (OM) and a trajectory of educational and social disadvantage.

METHODS

In two sequential parallel, open-label, randomised controlled trials, eligible infants were first allocated 1:1:1 to standard or mixed PCV primary schedules at age 28-38 days, then at age 12 months to a booster dose (1:1) of 13-valent PCV, PCV13 (Prevenar13®, +P), or 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugated vaccine, PHiD-CV10 (Synflorix®, +S). Here we report findings of standardised ear assessments conducted six-monthly from age 12-36 months, by booster dose.

RESULTS

From March 2013 to September 2018, 261 children were allocated to booster + P (n = 131) or + S (n = 130). There were no significant differences in prevalence of any OM diagnosis by booster dose or when stratified by primary schedule. We found high, almost identical prevalence of OM in both boost groups at each age (for example 88% of 129 and 91% of 128 children seen, respectively, at primary endpoint age 18 months, difference -3% [95% Confidence Interval -11, 5]). At each age prevalence of bilateral OM was 52%-78%, and tympanic membrane perforation was 10%-18%.

CONCLUSION

Despite optimal pneumococcal immunisation, the high prevalence of OM persists throughout early childhood. Novel approaches to OM prevention are needed, along with improved early identification strategies and evaluation of expanded valency PCVs.

Nasopharyngeal carriage of otitis media pathogens in infants receiving 10-valent non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10), 13-valent pneumococcal conjugate vaccine (PCV13) or a mixed primary schedule of both vaccines: A randomised controlled trial

BACKGROUND

Aboriginal children in Northern Australia have a high burden of otitis media, driven by early and persistent nasopharyngeal carriage of otopathogens, including non-typeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae (Spn). In this context, does a combined mixed primary series of Synflorix and Prevenar13 provide better protection against nasopharyngeal carriage of NTHi and Spn serotypes 3, 6A and 19A than either vaccine alone?

METHODS

Aboriginal infants (n = 425) were randomised to receive Synflorix™ (S, PHiD-CV10) or Prevenar13™ (P, PCV13) at 2, 4 and 6 months (_SSS or _PPP, respectively), or a 4-dose early mixed primary series of PHiD-CV10 at 1, 2 and 4 months and PCV13 at 6 months of age (SSSP). Nasopharyngeal swabs were collected at 1, 2, 4, 6 and 7 months of age. Swabs of ear discharge were collected from tympanic membrane perforations.

FINDINGS

At the primary endpoint at 7 months of age, the proportion of nasopharyngeal (Np) swabs positive for PCV13-only serotypes 3, 6A, or 19A was 0%, 0.8%, and 1.5% in the _PPP, _SSS, and SSSP groups respectively, and NTHi 55%, 52%, and 52% respectively, and no statistically significant vaccine group differences in other otopathogens at any age. The most common serotypes (in order) were 16F, 11A, 10A, 7B, 15A, 6C, 35B, 23B, 13, and 15B, accounting for 65% of carriage. Ear discharge swabs (n = 108) were culture positive for NTHi (52%), S. aureus (32%), and pneumococcus (20%).

CONCLUSIONS

Aboriginal infants experience nasopharyngeal colonisation and tympanic membrane perforations associated with NTHi, non-PCV13 pneumococcal serotypes and S. aureus in the first months of life. Nasopharyngeal carriage of pneumococcus or NTHi was not significantly reduced in the early 4-dose combined SSSP group compared to standard _PPP or _SSS schedules at any time point. Current pneumococcal conjugate vaccine formulations do not offer protection from early onset NTHi and pneumococcal colonisation in this high-risk population.

Addition of isovitalex in chocolate agar for the isolation of Haemophilus influenzae

BACKGROUND & OBJECTIVE

The reason for lack of data on burden of Haemophilus influenzae type b (Hib) in developing countries was mainly failure of detection of this fastidious organism in laboratories. Use of isovitalex (IVX) was suggested as an essential supplement for growing this organism. This study was carried out to investigate the impact of IVX supplementation to chocolate agar for detection of Hib.

METHODS

Chocolate agar with and without supplementation of IVX was prepared. Clinical samples as well as reference strains of Hib were simultaneously cultured on both the media.

RESULTS

H. influenzae isolates (N=194) were simultaneously grown on chocolate agar (CA) with and without isovitalex (IVX). Average colony size of H. influenzae on CA with IVX (CA-IVX) was larger only by 0.10 cm (range 0.05 to 0.16 cm) compared to CA alone. Addition of IVX to CA increased the cost of media by 2.1-fold.

INTERPRETATION & CONCLUSION

Isovitalex is not essential for the isolation and growth of H. influenzae almost halving the cost.

Vaccination greatly reduces disease, disability, death and inequity worldwide

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

Vaccination greatly reduces disease, disability, death and inequity worldwide

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

Validation of accuracy and community acceptance of the BIRTHweigh III scale for categorizing newborn weight in rural India

OBJECTIVE

To determine the accuracy and acceptability of a handheld scale prototype designed for nonliterate users to classify newborns into three weight categories (>or=2,500 g; 2,000 to 2,499 g; and <2,000 g).

STUDY DESIGN

Weights of 1,100 newborns in Uttar Pradesh, India, were measured on the test scale and validated against a gold standard. Mothers, family members and community health stakeholders were interviewed to assess the acceptability of the test scale.

RESULT

The test scale was highly sensitive and specific at classifying newborn weight (normal weight: 95.3 and 96.3%, respectively; low birth weight: 90.4 and 99.2%, respectively; very low birth weight: 91.7 and 98.4%, respectively). It was the overall agreement of the community that the test scale was more practical and easier to interpret than the gold standard.

CONCLUSION

The BIRTHweigh III scale accurately identifies low birth weight and very low birth weight newborns to target weight-specific interventions. The scale is extremely practical and useful for resource-poor settings, especially those with low levels of literacy.

Feasibility of community neonatal death audits in rural Uttar Pradesh, India

OBJECTIVE

Medical audit is a widely promoted strategy in hospitals, but experience within community settings is scant. Community neonatal death audit is a form of audit, which involves a systematic analysis of the quality of care provided in the home, danger sign recognition and care seeking decision making for neonatal illness. This research was conducted in Uttar Pradesh, India, to investigate the feasibility and cultural acceptability of community neonatal death audits.

STUDY DESIGN

During November-December 2004, we conducted three in-depth interviews with family members of deceased neonates, and six focus group discussions with family and community members. Three approaches were evaluated: in-depth interview with the family before engaging them in an audit with the community; preliminary meeting to build rapport with the family and community before conducting an audit; and audit with the family and community in a single focus group. Approaches were interactive processes, involving the community, to identify avoidable factors in a particular death and discuss solutions.

RESULT

Carried out in a culturally sensitive and non-punitive manner, community neonatal death audit was found to be acceptable and feasible. All approaches provoked formal investigation by community members, and stimulated sharing of views, leading to the self-discovery that community perception was a cumulatively amplified effect of individual perceptions. Presence of an educated/experienced community member or health worker served as a catalyst. No one optimal approach was identified.

CONCLUSION

Community neonatal audit is an acceptable approach that shows promise as an effective intervention for improving neonatal health outcomes.

Newborn care in rural Uttar Pradesh

OBJECTIVES

To describe selected newborn care practices related to cord care, thermal care and breastfeeding in rural Uttar Pradesh and to identify socio-demographic, antenatal and delivery care factors that are associated with these practices.

METHODS

A cross-sectional survey in rural Uttar Pradesh included 13,167 women who had a livebirth at home during the two years preceding data collection. Logistic regression was used to identify socio-demographic, antenatal and delivery care factors that were associated with the three care practices.

RESULTS

Use of antenatal care and skilled attendance at delivery were significantly associated with clean cord care and early breastfeeding, but not with thermal care. Antenatal home visits by a community-based worker were associated only with clean cord care. Women who received counseling from health workers or other sources on each of the newborn care practices during pregnancy were more likely to report the respective care practices, although levels of counseling were low.

CONCLUSION

The association between newborn care practices and antenatal care, counseling and skilled delivery attendance suggest that evidence-based newborn care practices can be promoted through improved coverage with existing health services.

Rates, timing and causes of neonatal deaths in rural India: implications for neonatal health programmes

OBJECTIVE

To assess the rates, timing and causes of neonatal deaths and the burden of stillbirths in rural Uttar Pradesh, India. We discuss the implications of our findings for neonatal interventions.

METHODS

We used verbal autopsy interviews to investigate 1048 neonatal deaths and stillbirths.

FINDINGS

There were 430 stillbirths reported, comprising 41% of all deaths in the sample. Of the 618 live births, 32% deaths were on the day of birth, 50% occurred during the first 3 days of life and 71% were during the first week. The primary causes of death on the first day of life (i.e. day 0) were birth asphyxia or injury (31%) and preterm birth (26%). During days 1-6, the most frequent causes of death were preterm birth (30%) and sepsis or pneumonia (25%). Half of all deaths caused by sepsis or pneumonia occurred during the first week of life. The proportion of deaths attributed to sepsis or pneumonia increased to 45% and 36% during days 7-13 and 14-27, respectively.

CONCLUSION

Stillbirths and deaths on the day of birth represent a large proportion of perinatal and neonatal deaths, highlighting an urgent need to improve coverage with skilled birth attendants and to ensure access to emergency obstetric care. Health interventions to improve essential neonatal care and care-seeking behavior are also needed, particularly for preterm neonates in the early postnatal period.

Introduction of community-based skin-to-skin care in rural Uttar Pradesh, India

OBJECTIVE

Two-thirds of women globally give birth at home, yet little data are available on use of skin-to-skin care (STSC) in the community. We describe the acceptability of STSC in rural Uttar Pradesh, India, and measured maternal, newborn, and ambient temperature in the home in order to inform strategies for introduction of STSC in the community.

STUDY DESIGN

Community-based workers in intervention clusters implemented a community mobilization and behavior change communication program that promoted birth preparedness and essential newborn care, including adoption of STSC, with pregnant mothers, their families, and key influential community members. Acceptance of STSC was assessed through in-depth interviews and focus groups, and temperature was measured during home visits on day of life 0 or 1.

RESULTS

Incidence of hypothermia (<36.5 degrees C) was high in both low birth weight (LBW) and normal birth weight (NBW) infants (49.2%, (361/733) and 43% (418/971), respectively). Mean body temperature of newborns was lower (P<0.01) in ambient temperatures <20 degrees C (35.9+/-1.4 degrees C, n=225) compared to > or =20 degrees C (36.5+/-0.9 degrees C, n=1450). Among hypothermic newborns, 42% (331/787) of their mothers had a lower temperature (range -6.7 to 0.1 degrees C, mean difference 0.4+/-1.2 degrees C). Acceptance of STSC was nearly universal. No adverse events from STSC were reported. STSC was perceived to prevent newborn hypothermia, enhance mother's capability to protect her baby from evil spirits, and make the baby more content.

CONCLUSION

STSC was highly acceptable in rural India when introduced through appropriate cultural paradigms. STSC may be of benefit for all newborns and for many mothers as well. New approaches are needed for introduction of STSC in the community compared to the hospital.

Evaluation of the indirect effects of a pneumococcal vaccine in a community-randomized study

When a sufficiently high proportion of a population is immunized with a vaccine, reduction in secondary transmission of disease can confer significant protection to unimmunized population members. We propose a straightforward method to estimate the degree of this indirect effect of vaccination in the context of a community-randomized vaccine trial. A conditional logistic regression model that accounts for within-randomization unit correlation over time is described, which models risk of disease as a function of community-level covariates. The approach is applied to an example data set from a pneumococcal conjugate vaccine study, with study arm and immunization levels forming the covariates of interest for the investigation of indirect effects.

Impact of topical oils on the skin barrier: possible implications for neonatal health in developing countries

Topical therapy to enhance skin barrier function may be a simple, low-cost, effective strategy to improve outcome of preterm infants with a developmentally compromised epidermal barrier, as lipid constituents of topical products may act as a mechanical barrier and augment synthesis of barrier lipids. Natural oils are applied topically as part of a traditional oil massage to neonates in many developing countries. We sought to identify inexpensive, safe, vegetable oils available in developing countries that improved epidermal barrier function. The impact of oils on mouse epidermal barrier function (rate of transepidermal water loss over time following acute barrier disruption by tape-stripping) and ultrastructure was determined. A single application of sunflower seed oil significantly accelerated skin barrier recovery within 1 h; the effect was sustained 5 h after application. In contrast, the other vegetable oils tested (mustard, olive and soybean oils) all significantly delayed recovery of barrier function compared with control- or Aquaphor-treated skin. Twice-daily applications of mustard oil for 7 d resulted in sustained delay of barrier recovery. Moreover, adverse ultrastructural changes were seen under transmission electron microscopy in keratin intermediate filament, mitochondrial, nuclear, and nuclear envelope structure following a single application of mustard oil.

CONCLUSION

Our data suggest that topical application of linoleate-enriched oil such as sunflower seed oil might enhance skin barrier function and improve outcome in neonates with compromised barrier function. Mustard oil, used routinely in newborn care throughout South Asia, has toxic effects on the epidermal barrier that warrant further investigation.

Nasopharyngeal carriage of resistant pneumococci in young South Indian infants

Streptococcus pneumoniae is the leading bacterial cause of life-threatening infections in infants. Although antibiotic resistance affects management of pneumococcal infections, few data on patterns of resistance are available for India. We examined nasopharyngeal carriage of antibiotic-resistant pneumococci in 464 South Indian infants between 2 and 6 months. Newly acquired serotypes were screened for susceptibility to cotrimoxazole, erythromycin and penicillin using disk diffusion. Cumulative prevalence of pneumococcal carriage rose from 53.9% at 2 months to 70.2% at 6 months. The prevalence of strains that were not susceptible to penicillin, cotrimoxazole and erythromycin was 34, 81.1 and 37.2%, respectively. Carriage of erythromycin non-susceptible strains declined significantly between ages 4 months and 6 months (44.1 vs. 10.7%). More than 87% of the isolates screened were non-susceptible to > or = 1 antibiotic. Serogroups/types that were most frequently non-susceptible to 1 or more antibiotics were 6, 9, 14, 19 and 23. Less than 1% of the isolates were multi-drug resistant. Widespread use of antibiotics in South India has resulted in S. pneumoniae becoming non-susceptible to some commonly used antibiotics. Monitoring trends in antibiotic susceptibility and making antibiotics available only through prescription from a health care worker may slow the spread of resistant pneumococci and improve management of pneumococcal infections in South India.

Safety and antibody persistence following Haemophilus influenzae type b conjugate or pneumococcal polysaccharide vaccines given before pregnancy in women of childbearing age and their infants

BACKGROUND

Immunization of healthy women before pregnancy is a potential approach to providing increased levels of maternal antibody to newborns to protect them from infections occurring during the perinatal period and first months of life.

METHODS

Healthy nonpregnant Pima Indian women of childbearing age were randomized to receive one of two Haemophilus influenzae type b (Hib) conjugate vaccines [HbOC or Hib-meningococcal outer membrane protein complex (OMP)] or a 23-valent pneumococcal polysaccharide vaccine (PnPs). Infants received Hib-OMP vaccine at 2, 4 and 12 months of age. Vaccine safety and immunogenicity was evaluated in the women and their infants.

RESULTS

Anti-polyribose ribitol phosphate antibody titers were significantly higher in women in both Hib conjugate vaccine groups than in the pneumococcal vaccine group throughout the 37-month observation period. Antibody responses to HbOC vaccine were significantly higher than those to Hib-OMP. A subsequent booster dose of each Hib conjugate vaccine induced reactions and antibody responses similar to those of the first dose. Infants born to mothers immunized with Hib vaccines compared with PnPs had significantly higher polyribose ribitol phosphate-specific IgG antibody titers at birth and 2 months of age but lower antibody responses to Hib-OMP at 6 months and similar titers before and after boosting with Hib-OMP at 1 year of age. By contrast women immunized with PnPs did not have significantly elevated concentrations of pneumococcal-specific antibody at delivery, and their infants had pneumococcal antibody titers similar to those of infants born to mothers who did not receive pneumococcal vaccine before pregnancy.

CONCLUSION

Hib conjugate vaccine given to women before pregnancy significantly increased the proportion of infants who had protective Hib antibody levels at birth and 2 months of age.

Rapid identification and antibiotic susceptibility testing of Salmonella enterica serovar Typhi isolated from blood: implications for therapy

The turnaround time (TAT) for Salmonella enterica serovar Typhi identification and reporting of the antibiotic susceptibility profile was determined for 391 cases of typhoid fever, using the lysis direct plating or lysis centrifugation method of blood culture along with rapid antimicrobial susceptibility testing. The TAT was more rapid (TAT for 90% of the patients [TAT(90)] = 30 h; TAT(100) Collapse

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MESH Headings

• Adolescent
• Adult
• Anti-Bacterial Agents/pharmacology
• Anti-Bacterial Agents/therapeutic use
• Bacteremia/drug therapy
• Bacteremia/microbiology
• Blood/microbiology
• Centrifugation
• Child
• Culture Media
• Drug Resistance, Multiple, Bacterial
• Hemolysis
• Humans
• Microbial Sensitivity Tests/methods
• Salmonella typhi/classification
• Salmonella typhi/drug effects
• Time Factors
• Typhoid Fever/drug therapy
• Typhoid Fever/microbiology

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Grants Collapse

Affiliation(s)

S K Saha Department of Microbiology, Institute of Child Health, Dhaka Shishu Hospital, Dhaka, Bangladesh.
G L Darmstadt
A H Baqui
M Hanif
M Ruhulamin
M Santosham
T Nagatake
R E Black

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Design of a group-randomized Streptococcus pneumoniae vaccine trial

A group-randomized, double-masked, phase III trial of a Streptococcus pneumoniae conjugate vaccine is being conducted in American Indian populations in the southwestern United States. Approximately 9000 infants will be enrolled in the primary efficacy cohort with vaccine allocation determined by community of residence. The trial is designed to continue until 48 cases of invasive pneumococcal disease due to vaccine serotypes have accumulated. Thirty-eight geographically and socially distinct areas were randomized within blocks formed by population size and geographic location. This design affords the opportunity to capture the effects of herd immunity (indirect effects) by estimating the impact of the vaccine intervention on nonimmunized infants. Group-randomized trials have challenging design and analysis features, many of which are discussed here in the context of the first such trial designed to lead to licensure of a drug or biologic in the United States.

Typhoid fever in Bangladesh: implications for vaccination policy

OBJECTIVE

To describe the age-specific distribution of typhoid fever including the degree of Salmonella typhi bacteremia among patients evaluated at a large private diagnostic center in Bangladesh, a highly endemic area.

METHODS

We conducted a prospective-, passive- and laboratory-based study to identify patients with S. typhi bacteremia. Subjects (n = 4,650) from whom blood cultures were obtained during 16-month period were enrolled from private clinics and hospitals throughout Dhaka. Isolation and quantification of S. typhi from blood cultures were performed by the lysis direct plating/ centrifugation method.

RESULTS

Bacterial pathogens were recovered from blood of 538 of 4,650 patients (11.6%) evaluated. S. typhi was the single most common pathogen recovered, comprising nearly three-fourths of isolates (72.7%; 391 of 538). Isolation rate of S. typhi was highest in monsoon and summer seasons and lowest in winter months. The majority (54.5%; 213 of 391) of S. typhi isolates were from children who were younger than 5 years, and 27% (105 of 391) were from children in the first 2 years of life. The isolation rate was highest (17.4%, 68 of 486) in the second year of life. The number of bacteria in blood on the basis of colony-forming units per ml of blood by age group was inversely related to age.

CONCLUSIONS

Detection of S. typhi bacteremia in young children in Dhaka, Bangladesh, was considerably higher than previously appreciated, with a peak detection rate in children < or =2 years of age, indicating the need to reassess the age-specific burden of typhoid fever in the community on a regional basis. Contrary to current recommendations this study suggests that development of new vaccines should target infants and young children.

Pneumococcal nasopharyngeal colonization in young South Indian infants

BACKGROUND

Streptococcus pneumoniae is the most frequent bacterial cause of morbidity and mortality in young children. Bacteria carried in the nasopharynx of healthy children reflect the prevalent strains circulating in the community.

METHODS

We recruited 464 newborns from a rural area in South India with endemic vitamin A deficiency. Nasopharyngeal specimens were collected from each infant at ages 2, 4 and 6 months.

RESULTS

Fifty-four percent of study infants were colonized by age 2 months, with 64.1 and 70.2% carriage prevalence at ages 4 and 6 months, respectively. The odds of carriage at 2 months were significantly increased in female infants, infants living in a household in which 20 or more cigarettes were smoked each day, infants whose mothers had less than 1 year of schooling and infants fed colostrum. At age 4 months infants having 2 or more siblings <5 years of age were at significantly increased risk of carriage. At age 6 months none of the potential risk factors examined achieved statistical significance, but maternal night blindness increased the risk of colonization 3-fold. The odds of carrying a PncCRM197 vaccine serotype were increased among infants born to mothers who experienced night blindness during pregnancy. The most prevalent serogroups/types during the first 6 months of life were 6, 9, 10, 11, 14, 15, 19, 23 and 33, accounting for 76.7% of all serotyped isolates.

CONCLUSIONS

South Indian infants experience high rates of pneumococcal carriage during the first 6 months of life, which may partially explain their increased risk for pneumonia.

Safety and immunogenicity of heptavalent pneumococcal vaccine conjugated to CRM(197) among infants with sickle cell disease. Pneumococcal Conjugate Vaccine Study Group

OBJECTIVES

To determine the immunogenicity and safety of heptavalent pneumococcal polysaccharide vaccine (serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F) conjugated to CRM(197) (7-valent conjugate pneumococcal vaccine [7VPnC]) among infants with sickle cell disease (SCD) and a comparison group of infants without SCD (non-SCD).

DESIGN

Two cohorts of infants were enrolled and received open-label doses of 7VPnC vaccine; infants enrolled before 2 months of age received 7VPnC vaccine at 2, 4, and 6 months of age followed by 23-valent pneumococcal polysaccharide vaccine (PS-23) at 24 months of age for those infants with SCD (schedule A), and infants enrolled between 2 and 12 months of age received 7VPnC at 12 months of age followed by PS-23 at 24 months of age for infants with SCD (schedule B). Safety data were collected for 3 days after each dose of vaccine. Antibody concentrations were measured to each of the 7VPnC serotypes by enzyme-linked immunosorbent assay before each vaccine dose and 1 month after the last 7VPnC dose and the PS-23 vaccine dose.

RESULTS

Forty-five infants (34 SCD and 11 non-SCD) were vaccinated according to schedule A and 16 infants (13 SCD and 3 non-SCD) according to schedule B. The 7VPnC vaccine was highly immunogenic for all serotypes among infants with and without SCD who received 3 doses of vaccine according to schedule A: depending on serotype, 89% to 100% achieved antibody concentrations above.15 microg/mL and 56% to 100% achieved antibody concentrations above 1.0 microg/mL. Among infants immunized according to schedule B, a single dose of 7VPnC vaccine resulted in antibody concentrations above.15 microg/mL in 53% to 92% by serotype and above 1.0 microg/mL in 31% to 71% by serotype. A single dose of PS-23 resulted in dramatic increases in the antibody concentrations to all serotypes regardless of 1- or 3-dose priming. There was no difference in the reactogenicity of the 7VPnC vaccine between those with and without SCD. There were no serious reactions to the 7VPnC or PS-23 vaccines, even among those with high antibody concentrations before immunization.

CONCLUSIONS

Infants with SCD respond to 7VPnC vaccine with antibody concentrations that are at least as high as infants without SCD. Infants immunized with 7VPnC vaccine at 2, 4, and 6 months of age developed antibody concentrations in the same range as those achieved among infants without SCD enrolled in a large trial that demonstrated vaccine efficacy against invasive disease. Significant rises were seen in antibody concentrations to all 7VPnC serotypes after the PS-23 booster in children receiving schedule A or B.

Toward elimination of Haemophilus influenzae type B carriage and disease among high-risk American Indian children

OBJECTIVES

This report describes the epidemiology of Haemophilus influenzae type b (Hib) invasive disease and oropharyngeal colonization among Navajo and White Mountain Apache children younger than 7 years in an era of widespread immunization.

METHODS

We conducted active surveillance for invasive H influenzae disease from 1992 to 1999 and an oropharyngeal carriage study from 1997 to 1999. The predominant vaccine used was PedvaxHib.

RESULTS

The average annual incidence of invasive Hib disease among children younger than 24 months was 22 cases per 100,000. Of 381 children younger than 7 years, only 1 (0.3%; 95% confidence interval = 0.0%, 1.3%) was colonized with Hib; 370 (97%) had received 2 or more doses of Hib conjugate vaccine.

CONCLUSIONS

Among Navajo and White Mountain Apache children, Hib conjugate vaccines have led to a sustained reduction in invasive Hib disease and a reduction in oropharyngeal Hib carriage. The disease incidence among children younger than 24 months remains 20 times higher than in the general US population. Hib elimination will require additional characterization of colonization and disease in these high-risk populations.

Estimation of the indirect effect of Haemophilus influenzae type b conjugate vaccine in an American Indian population

BACKGROUND

Oropharyngeal carriage studies of Haemophilus influenzae type b (Hib) and the rapid drop in Hib invasive disease in countries with widespread Hib conjugate vaccine immunization programmes for infants have indicated there may be significant indirect effects (herd immunity) associated with these vaccines. Our goal was to quantify the magnitude of these effects in an American Indian population during its early years of Hib immunization.

METHODS

In a synthetic case-cohort study, we combined data from an efficacy trial, an immunization uptake records survey, and ongoing surveillance for Hib disease on the Navajo Nation from 1988 to 1992. Decline in the incidence of invasive Hib disease among children <2 years old was estimated via proportional hazards survival models as a function of individual immunization status and the proportion of immunized children in a community.

RESULTS

The predominant vaccine during the study period was Hib-OMPC (92% of immunizations). The effectiveness of receipt of at least one dose was 97.2%. Compared to communities with 0-20% coverage with at least one dose, residence in communities with 20-40% and 40-60% coverage was associated with risk reductions of 56.5% and 73.2%, respectively.

CONCLUSIONS

The results indicate substantial indirect effects of Hib-OMPC immunization may occur even at relatively low levels of immunization coverage. Countries that implement Hib immunization programmes may receive greater benefits at the community level than those due to the direct protection conferred to the individual through vaccination.

The World Health Organization oral rehydration solution in US pediatric practice: a randomized trial to evaluate parent satisfaction

BACKGROUND

The World Health Organization's effective, inexpensive oral rehydration solution (WHO-ORS) is used worldwide, but rarely by US practitioners because, in part, of concerns about parent satisfaction.

OBJECTIVE

To compare caretaker satisfaction with the WHO-ORS, a packet-based solution requiring preparation, with satisfaction with a commercially prepared oral rehydration solution (C-ORS), (Pedialyte; Ross Nutritionals, Columbus, Ohio).

DESIGN AND METHODS

Randomized controlled trial in an urban pediatric clinic and a suburban family medicine clinic. Children aged 3 to 47 months treated as outpatients for diarrhea were randomized to receive either WHO-ORS or C-ORS. After 48 hours of use, caretakers completed a telephone interview measuring satisfaction with aspects of the solution.

RESULTS

Of 97 families enrolled, 91 (94%) were available for follow-up interviews. The WHO-ORS and C-ORS groups were comparable at baseline in all respects, except that slightly more caretakers in the latter group had used the C-ORS for the current illness before study enrollment (P= .06). Caretakers in the WHO-ORS group had higher overall satisfaction, satisfaction with cost, willingness to purchase in the future, and to recommend use (P<.001 for all). Differences remained significant after controlling for prior use of the C-ORS. There was no difference in satisfaction with ease of administration (P=.90), appearance (P=.20), and effectiveness (P=.80). No adverse effects attributable to either study solution occurred.

CONCLUSIONS

Caretakers who prepared and used the WHO-ORS were more satisfied with their solution than a comparable group who administered C-ORS. Fear of parental dissatisfaction need not be a barrier to use of the WHO-ORS in the United States.

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.

Simultaneous vitamin A administration at routine immunization contact enhances antibody response to diphtheria vaccine in infants younger than six months

A randomized, double-blind, placebo-controlled trial was conducted to evaluate the effect of simultaneous vitamin A supplementation and diphtheria, pertussis and tetanus (DPT) vaccination on the antibody levels. Infants aged 6-17 wk (n = 56) were randomly given 15 mg oral vitamin A or placebo at the time of their DPT immunization. Three such doses were given at monthly intervals. Immunoglobulin (Ig) G antibodies to diphtheria, pertussis and tetanus were assayed on enrollment and 1 mo after the third dose. Baseline antibody concentrations to diphtheria, pertussis and tetanus did not differ between the vitamin A-supplemented and placebo-treated groups. The postdose antibody to diphtheria level was significantly greater in the vitamin A than in the placebo-treated group. The geometric mean +/- SEM antibody levels (mg/L) were 22.9 +/- 1.2 and 11.0 +/- 1.3 in the vitamin A and placebo groups, respectively (P = 0.029). The postsupplementation concentrations of antibodies to pertussis and tetanus did not differ between the two groups. These results suggest that antibody response to diphtheria vaccination was potentiated by simultaneous vitamin A administration and DPT immunization.

Severe respiratory syncytial virus disease in Alaska native children. RSV Alaska Study Group

Hospitalization rates for respiratory syncytial virus (RSV) infection range from 1 to 20/1000 infants. To determine the rate and severity of RSV infections requiring hospitalization for infants in the Yukon-Kuskokwim (YK) Delta of Alaska, a 3-year prospective surveillance study was conducted. The annual rate of RSV hospitalization for YK Delta infants <1 year of age was 53-249/1000. RSV infection was the most frequent cause of infant hospitalization. RSV disease severity did not differ among non-high-risk infants in the YK Delta and at Johns Hopkins Hospital (JHH). On average, 1/125 infants born in the YK Delta required mechanical ventilation for RSV infection. During the peak season, approximately $1034/child <3 years of age was spent on RSV hospitalization in the YK Delta. In YK Delta infants </=6 months old, RSV microneutralizing antibody titers <1200 were associated with severe disease (odds ratio=6.2, P=.03). In the YK Delta and at JHH, newborns may be at greater risk for severe RSV illness than previously thought.

Comparison of soy-based formulas with lactose and with sucrose in the treatment of acute diarrhea in infants

OBJECTIVE

To evaluate the effect of feeding infants a soy-based formula with lactose compared with a soy-based formula with sucrose during an acute diarrheal episode.

PARTICIPANTS AND METHODS

Two hundred boys, aged 3 to 18 months, who were admitted to the hospital with acute diarrhea and signs of dehydration were randomly assigned to receive a soy-based formula with lactose or sucrose after initial rehydration. Intake and output (stool, urine, and vomit) were measured and recorded every 3 hours until diarrhea resolved.

RESULTS

The stool output during the first 24 hours of maintenance therapy, the total stool output during maintenance therapy, and the stool output during the entire illness (measured in grams per kilograms) were significantly lower among patients who received the soy-based formula with sucrose (P<.05, P<.001, and P<.001, respectively) than among patients who received the soy-based formula with lactose. The duration of diarrhea was significantly shorter among patients who received the soy-based formula with sucrose (P<.001). The relative risk of being withdrawn from the study increased to 1.95 (95% confidence interval, 0.65-9.2) and the relative risk of recurrence of dehydration after feeding was initiated increased significantly to 3.49 (95% confidence interval, 1.1-9.6; P<.01) in the group receiving the soy-based formula with lactose.

CONCLUSION

During diarrheal episodes, feeding infants a soy-based formula with sucrose has a better outcome (lower stool output, shorter duration of diarrhea, and lower failure rates) than feeding infants a soy-based formula with lactose.

A case-control study of risk factors for Haemophilus influenzae type B disease in Navajo children

To understand the potential risk factors and protective factors for invasive Haemophilus influenzae type b (Hib) disease, we conducted a case-control study among Navajo children less than two years of age resident on the Navajo Nation. We analyzed household interview data for 60 cases that occurred between August 1988 and February 1991, and for 116 controls matched by age, gender, and geographic location. The Hib vaccine recipients were excluded from the analyses. Conditional logistic regression models were fit to examine many variables relating to social and environmental conditions. Risk factors determined to be important were never breast fed (odds ratio [OR] = 3.55, 95% confidence interval [CI] = 1.52, 8.26), shared care with more than one child less than two years of age (OR = 2.32, 95% CI = 0.91, 5.96); wood heating (OR = 2.14, 95% CI = 0.91, 5.05); rodents in the home (OR = 8.18, 95% CI = 0.83, 80.7); and any livestock near the home (OR = 2.18, 95% CI = 0.94, 5.04).

The protective effectiveness of natural rotavirus infection in an American Indian population

The degree of protection conferred by natural rotavirus infection was estimated through analyses of data gathered as part of a 2-year rotavirus vaccine study of 1185 Native American infants. In 292 placebo recipients with complete serum sample sets, rotavirus IgA antibody indicative of infection before 2 months of age was associated with a 58% decrease in symptomatic infections throughout the trial. In all 391 placebo recipients, the preventive effectiveness of an initial symptomatic infection was 72% overall and 94% within 6 months following the infection. In contrast to studies conducted at other sites in the United States, serotype G3 was the predominant serotype associated with gastrointestinal episodes (80%). The effectiveness of an initial serotype G3 episode with respect to preventing subsequent serotype G3 episodes was 91%.

Oral rehydration therapy for diarrhea: an example of reverse transfer of technology

On November 13 and 14, 1996, a scientific symposium on oral rehydration therapy (ORT) was held at the Johns Hopkins University School of Hygiene and Public Health in Baltimore, MD. The purpose of the meeting was to review the current treatment practices for the treatment of this disease in the United States. The group noted that diarrhea resulted in 300 to 400 deaths per year among children, approximately 200 000 hospitalizations, 1.5 million outpatient visits, and costs >$1 billion in direct medical costs. ORT is well established therapy for the treatment and prevention of dehydration due to diarrhea. The principles of ORT treatment include early adequate rehydration therapy using an appropriate oral rehydration solution (ORS), replacement of ongoing fluid losses from vomiting and diarrhea with ORS, and frequent feeding of appropriate foods as soon as dehydration is corrected. The effective use of ORT has saved millions of lives around the world. However, in the United States, ORT is grossly underused. Contrary to the recommendations of the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC), health care providers overuse intravenous hydration, prolong rehydration, delay reintroduction of feeding, and inappropriately withhold ORT, especially with children who are vomiting. The expert panel noted that the majority of deaths, hospitalization, and visits to emergency departments could be prevented by the appropriate use of ORT. They generated guidelines for the treatment and prevention of dehydration secondary to diarrhea. These measures, together with training providers, could substantially reduce diarrhea mortality and decrease hospitalizations of children by 100 000 per year in the next 5 years.

Efficacy and safety of high-dose rhesus-human reassortant rotavirus vaccine in Native American populations

OBJECTIVES

We compared the efficacy, safety, and immunogenicity of a rhesus rotavirus tetravalent vaccine (RRV-TV), a rhesus rotavirus monovalent (serotype 1) vaccine (RRV-S1), and placebo in healthy American Indian infants for two rotavirus seasons.

STUDY DESIGN

Infants aged 6 to 24 weeks were enrolled in a randomized, double-blind efficacy study. Infants were orally administered RRV-TV (4 x 10(5) plaque-forming units per dose), RRV-S1 (4 x 10(5) plaque-forming units per dose), or placebo at 2, 4, and 6 months of age. Stools collected during episodes of gastroenteritis were tested for detection of rotavirus antigen. A total of 1185 infants received at least one dose of a study vaccine or placebo, and 1051 received all three doses according to the protocol.

RESULTS

During the first year of surveillance, the estimates of vaccine efficacy (with 95% confidence interval) for preventing rotaviral gastroenteritis were 50% (26, 67) for RRV-TV and 29% (-1, 50) for RRV-S1. In this population only 6% of rotaviral gastroenteritis episodes among placebo recipients were associated with type G1 disease. For severe disease the estimates of vaccine efficacy were higher: 69% (29, 88) for RRV-TV and 48% (-4, 75) for RRV-S1.

CONCLUSIONS

These data indicate that RRV-TV is moderately efficacious in preventing all episodes of gastroenteritis caused by rotavirus and is most efficacious against the severe disease characteristic of rotaviral illness.

Comparison of two regimens of feeding and oral electrolyte solutions in infants with diarrhea

BACKGROUND

Glucose-based oral rehydration solutions (ORS) available in the United States do not appear to reduce the severity or duration of diarrhea. The use of cereal-derived ORS and cereal-based feedings appears to diminish the severity of illness in studies conducted in the developing world. To our knowledge, no controlled trials of cereal-derived ORS or cereal-based feedings have been performed in the United States.

METHODS

We performed a randomized, double-blind trial of two ORS feeding regimens in outpatients with diarrhea. Patients aged 2-13 months with acute watery diarrhea were enrolled. Subjects received standard glucose-based ORS in alternation with soy-based, lactose-free infant formula (Group 1) or rice syrup solid containing ORS in alternation with rice-based, lactose-free infant formula (Group 2). Subjects were visited at home daily to determine the severity of illness and characteristics of the stool.

RESULTS

After the first 2 days, significantly more Group 1 subjects continued to have diarrhea than did Group 2 subjects (median duration of diarrhea 3 vs. 2 days) as demonstrated by Kaplan-Meier survival curves (p = 0.04).

CONCLUSION

We conclude that infants fed a regimen consisting of rice syrup solid containing ORS and rice formula resolved their diarrhea sooner than did infants fed a regimen of standard glucose-based ORS and formula. The relative contributions of ORS and formula to this more rapid recovery can be elucidated by further studies.

The cost effectiveness of oral rehydration therapy for U.S. children with acute diarrhea

Diarrheal disease is a common cause of morbidity among U.S. children under five years of age and exerts a heavy burden on the health care system. Oral rehydration therapy (ORT), a simple, inexpensive treatment modality that can prevent most diarrhea-related complications, is grossly underutilized in the United States. Using a decision-analysis model, this article describes the financial burden of childhood diarrhea in the United States for children under five years of age and discusses the substantial economic benefits of ORT programs. If fully implemented, such programs would save our health care system close to $1 billion annually.

Wood-burning stoves and lower respiratory illnesses in Navajo children

BACKGROUND

Acute lower respiratory illnesses (ALRI) have been associated with exposure to domestic smoke. To examine further this association, a case-control study was conducted among Navajo children seen at the Public Health Service Indian Hospital at Fort Defiance, AZ.

METHODS

Cases, children hospitalized with an ALRI (n = 45), were ascertained from the inpatient logs during October, 1992, through March, 1993. Controls, children who had a health record at the same hospital and had never been hospitalized for ALRI, were matched 1:1 to cases on date of birth and gender. Home interviews of parents of subjects during March and April, 1993, elicited information on heating and cooking fuels and other household characteristics. Indoor air samples were collected for determination of time-weighted average concentrations of respirable particles (i.e. < 10 microns in diameter).

RESULTS

Age of cases at the time of admission ranged from 1 to 24 months (median, 7 months); 60% of the cases were male. Matched pair analysis revealed an increased risk of ALRI for children living in households that cooked with any wood (odds ratio (OR), 5.0; 95% confidence interval (CI), 0.6 to 42.8), had indoor air concentrations of respirable particles > or = 65 micrograms/m3 (i.e. 90th percentile) (OR 7.0, 95% CI 0.9 to 56.9), and where the primary caretaker was other than the mother (OR 9, 95% CI 1.1 to 71.4). Individual adjustment for potential confounders resulted in minor change (i.e. < 20%) in these results. Indoor air concentration of respirable particles was positively correlated with cooking and heating with wood (P < 0.02) but not with other sources of combustion emissions.

CONCLUSIONS

Cooking with wood-burning stoves was associated with higher indoor air concentrations of respirable particles and with an increased risk of ALRI in Navajo children.

Effect of diarrhea on the humoral response to oral polio vaccination

OBJECTIVE

The purpose of this study was to measure the effect of concurrent diarrheal illness on seroconversion to trivalent oral polio vaccine (OPV).

METHODS

Six- to 16-week-old infants with acute diarrhea and age-matched controls received single doses of OPV at enrollment, 4 weeks after enrollment and 8 weeks after enrollment. Serum specimens were obtained at enrollment, before the second OPV dose and 4 weeks after the third OPV dose for measurement of antibody titers to polio virus by the microneutralization assay.

RESULTS

Four weeks after the first OPV dose, the serologic responses to poliovirus types 2 and 3 in the case cohort were lower by 26 and 34%, respectively, than in the control cohort (P < 0.002 for both comparisons). Poliovirus type 2 and 3 geometric mean antibody titers in the diarrhea cohort were approximately 50% of the geometric mean antibody titers in the control cohort (235 (95% confidence interval (CI) 154 to 359) vs. 446 (95% CI 350 to 569) and 64 (95% CI 45 to 90) vs. 112 (95% CI 88 to 143), respectively, P < 0.01 for both comparisons). After the third OPV dose the seroconvertion rates to poliovirus types 2 and 3 each remained about 10% lower in the case cohort than in the control cohort, but the differences were not statistically significant.

CONCLUSION

Concurrent acute diarrhea adversely affects seroconvertion rates of type 2 and 3 polioviruses among infants in Bangladesh receiving the first dose of trivalent OPV.

How valid are clinical signs of dehydration in infants?

Our objective was to determine the ability of several clinical signs of dehydration to distinguish among degrees of dehydration in infants with acute diarrhea. The design was a prospective cohort study in a pediatric referral hospital in Cairo, Egypt. Infant boys, 3-18 months old, with a history of acute diarrhea (5 or more watery stools per day for no more than 7 days) were eligible, except those with frank protein-energy malnutrition, serious nongastrointestinal illness, or being exclusively breast-fed. Several clinical signs of dehydration were assessed upon study entry. Subjects were then rehydrated with an oral rehydration solution and fed a standardized diet until diarrhea ceased (no watery or loose stools for 16 h). The main outcome measure was percent body weight gain at rehydration and at resolution of illness. Data from 135 subjects were available for analysis. Average (SD) rehydration phase duration was 5.2 (2.1) h, and average (SD) duration of illness was 54.5 (38) h. Multiple regression analysis selected prolonged skinfold, altered neurologic status, sunken eyes, and dry oral mucosa as the clinical signs that correlated best with percent dehydration (R2 for model 0.244, p < 0.001). Mean weight gain for the two assessment systems was 3.6-3.9% for mild, 4.9-5.3% for moderate, and 9.5-9.8% for severe dehydration. The most valid clinical signs of dehydration include prolonged skinfold, altered neurologic status, sunken eyes, and dry oral mucosa. Children with clinical signs of mild or moderate dehydration have fluid deficits on the order of 3 or 5% body weight, respectively.

A double-blind clinical trial comparing World Health Organization oral rehydration solution with a reduced osmolarity solution containing equal amounts of sodium and glucose

OBJECTIVE

To compare the safety and efficacy of an oral rehydration solution (ORS) containing 75 mmol/L of sodium and glucose each with the standard World Health Organization (WHO) ORS among Egyptian children with acute diarrhea.

METHODS

One hundred ninety boys, aged 1 to 24 months, who were admitted to the hospital with acute diarrhea and signs of dehydration were randomly assigned to receive either standard ORS (311 mmol/L) or a reduced osmolarity ORS (245 mmol/L). Intake and output were measured every 3 hours.

RESULTS

In the group treated with reduced osmolarity ORS, the mean stool output during the rehydration phase was 36% lower (95% confidence interval, 1%, 100%) than in those treated with WHO ORS. The relative risk of vomiting during the rehydration phase was significantly lower in children treated with reduced osmolarity ORS (relative risk, 2.4; 95% confidence interval, 1.2, 4.8). During the maintenance phase, stool output, mean intake of food and ORS, duration of diarrhea, and weight gain were similar in the treatment groups. The relative risk of treatment failure (need for unscheduled administration of intravenous fluids) was significantly increased in children receiving standard WHO ORS (relative risk, 7.9; 95% confidence interval, 1.1, 60.9). The mean serum sodium concentration at 24 hours was significantly lower in children receiving the reduced osmolarity ORS solution (134 +/- 6 mEq/L) than in children receiving the standard WHO ORS (138 +/- 7 mEq/L) (p < 0.001). The relative risk of the development or worsening of hyponatremia was not increased in children given the reduced osmolarity ORS, and urine output was similar in the treatment groups.

CONCLUSION

The reduced osmolarity ORS has beneficial effects on the clinical course of acute diarrhea in children by reducing stool output, and the proportion of children with vomiting during the rehydration phase, and by reducing the need for supplemental intravenous therapy. These results provide support for the use of a reduced osmolarity ORS in children with acute noncholera diarrhea.

Oral prednisone as a risk factor for infections in children with asthma

OBJECTIVE

To determine whether the frequency of acute infections in children with asthma is associated with the number of doses of prednisone received for asthma attacks.

DESIGN

A cohort study.

SETTING

Primary care clinic and emergency department of an inner-city teaching hospital from March 31, 1992, to May 31, 1993.

PATIENTS

Convenience sample of clinic enrollees aged 2 to 14 years who had made two or more outpatient visits for acute asthma in the preceding year. Eighty-six children were enrolled. Seventy-eight (91%) completed the study.

MAIN OUTCOME MEASURES

The independent variable was cumulative prednisone dose received during the study period. Outcome variables were episodes of acute infections.

RESULTS

The mean (+/-SD) number of doses of prednisone (2 mg/kg to a maximum of 60 mg) received was 9.5 +/- 11.8 doses (range, 0 to 57 doses). Ninety-four episodes of acute infection occurred in 50 children. No difference was observed in the mean number of doses of prednisone received by those with the infection compared with those without the infection. No correlation was observed between the number of doses of prednisone received and the number of episodes of each infection.

CONCLUSIONS

The administration of prednisone as short courses for acute asthma is not associated with an increase in the number of episodes of common acute infections.

Case-cohort analysis of case-coverage studies of vaccine effectiveness

Evaluation of vaccine field effectiveness may be performed by combining surveillance data on incident cases with an immunization coverage survey. Although many methods have been used for the analysis of studies of similar design, they are not always desirable or optimal. The authors discuss these approaches and propose use of a case-cohort analysis for such a study design when appropriate. The case-cohort analytic approach is illustrated with data from studies of a vaccine for Haemophilus influenzae type b (Hib) disease in children living on a southwestern Native American reservation during 1988-1993.