Evaluation of Haemophilus influenzae Type b Vaccine for Routine Immunization in Nepali Infants

Metz, Jane; Hanieh, Sarah; Pradhan, Rahul; Joshi, Arbin; Shakya, Dhana Ratna; Shrestha, Lochan; Shrestha, Ashis; Upadhyay, Bishwas; Kelly, Sarah; John, Tessa M.; Maharjan, Bishnu Devi; Yu, Ly-Mee; Omar, Omar; Borrow, Raymond; Findlow, Jamie; Kelly, Dominic F.; Thorson, Stephen; Adhikari, Neelam; Murdoch, David R.; Pollard, Andrew J.

doi:10.1097/inf.0b013e31824a9c37

Cited by 6 publications

(6 citation statements)

References 27 publications

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“…The first, the decrease in Hib IgG concentrations from 24 to 48 weeks of age, may lead to levels below the protective threshold in the ensuing months, consistent with previous findings in both HIV-exposed and -unexposed infants (35,38,43). Such data have been invoked in support of a recommendation for a booster dose at 1 year.…”

Section: Discussionsupporting

confidence: 78%

“…Indeed, the vaccine responses in our study are typical of observations in non-HIV-exposed populations in developing countries, where initial Hib vaccine responses may be more vigorous than in higher-income populations (37), as observed in Nepal, South Africa, and Latin America, where 95 to 100% of the infants generate protective levels of Hib-specific IgG (Ͼ1 g/ml) after a primary series. Indeed, even fractional doses (a fraction of the typical dose) of vaccine have been highly immunogenic in developing countries (38)(39)(40)(41). Furthermore, Hib vaccine responses do not appear to be affected by combination with whole-cell pertussis vaccine, such as that used in our Ugandan cohort and many low-and middleincome nations, whereas acellular pertussis vaccines are associated with decreased Hib antibody responses when used in combination, a phenomenon that may explain the higher levels of Hib IgG at 1 year among the Ugandan infants in this study (42).…”

Section: Discussionmentioning

confidence: 99%

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Impaired Haemophilus influenzae Type b Transplacental Antibody Transmission and Declining Antibody Avidity through the First Year of Life Represent Potential Vulnerabilities for HIV-Exposed but -Uninfected Infants

Gaensbauer

Rakhola

Onyango‐Makumbi

et al. 2014

Clin. Vaccine Immunol.

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fTo determine whether immune function is impaired among HIV-exposed but -uninfected (HEU) infants born to HIV-infected mothers and to identify potential vulnerabilities to vaccine-preventable infection, we characterized the mother-to-infant placental transfer of Haemophilus influenzae type b-specific IgG (Hib-IgG) and its levels and avidity after vaccination in Ugandan HEU infants and in HIV-unexposed U.S. infants. Hib-IgG was measured by enzyme-linked immunosorbent assay in 57 Ugandan HIVinfected mothers prenatally and in their vaccinated HEU infants and 14 HIV-unexposed U.S. infants at birth and 12, 24, and 48 weeks of age. Antibody avidity at birth and 48 weeks of age was determined with 1 M ammonium thiocyanate. A median of 43% of maternal Hib-IgG was transferred to HEU infants. Although its level was lower in HEU infants than in U.S. infants at birth (P < 0.001), Hib-IgG was present at protective levels (>1.0 g/ml) at birth in 90% of HEU infants and all U.S. infants. HEU infants had robust Hib-IgG responses to a primary vaccination. Although Hib-IgG levels declined from 24 to 48 weeks of age in HEU infants, they were higher than those in U.S. infants (P ‫؍‬ 0.002). Antibody avidity, comparable at birth, declined by 48 weeks of age in both populations. Early vaccination of HEU infants may limit an initial vulnerability to Hib disease resulting from impaired transplacental antibody transfer. While initial Hib vaccine responses appeared adequate, the confluence of lower antibody avidity and declining Hib-IgG levels in HEU infants by 12 months support Hib booster vaccination at 1 year. Potential immunologic impairments of HEU infants should be considered in the development of vaccine platforms for populations with high maternal HIV prevalence.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Impaired Haemophilus influenzae Type b Transplacental Antibody Transmission and Declining Antibody Avidity through the First Year of Life Represent Potential Vulnerabilities for HIV-Exposed but -Uninfected Infants

Gaensbauer

Rakhola

Onyango‐Makumbi

et al. 2014

Clin. Vaccine Immunol.

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“…In vaccine trials in Niger and Nepal, 83–88% and 100% of infants, respectively, had post-primary vaccination concentrations of anti-PRP above 1 mg/mL, declining to 67–75% and 64%, respectively, by late infancy. 28 , 29 In Mali, 2 years after vaccine introduction and with coverage at 81%, 82% of infants aged 6–7 months had anti-PRP concentrations greater than 1 mg/mL. 30 In the same setting the following year, antibody decline did not begin until after 2 years of age.…”

Section: Discussionmentioning

confidence: 99%

Effect of Haemophilus influenzae type b vaccination without a booster dose on invasive H influenzae type b disease, nasopharyngeal carriage, and population immunity in Kilifi, Kenya: a 15-year regional surveillance study

Hammitt

Crane

Karani

et al. 2016

The Lancet Global Health

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SummaryBackgroundHaemophilus influenzae type b (Hib) conjugate vaccine, delivered as a three-dose series without a booster, was introduced into the childhood vaccination programme in Kenya in 2001. The duration of protection and need for a booster dose are unknown. We aimed to assess vaccine effectiveness, the impact of the vaccine on nasopharyngeal carriage, and population immunity after introduction of conjugate Hib vaccine in infancy without a booster dose in Kenya.MethodsThis study took place in the Kilifi Health and Demographic Surveillance System (KHDSS), an area of Kenya that has been monitored for vital events and migration every 4 months since 2000. We analysed sterile site cultures for H influenzae type b from children (aged ≤12 years) admitted to the Kilifi County Hospital (KCH) from Jan 1, 2000, through to Dec 31, 2014. We determined the prevalence of nasopharyngeal carriage by undertaking cross-sectional surveys in random samples of KHDSS residents (of all ages) once every year from 2009 to 2012, and measured Hib antibody concentrations in five cross-sectional samples of children (aged ≤12 years) within the KHDSS (in 1998, 2000, 2004–05, 2007, and 2009). We calculated incidence rate ratios between the prevaccine era (2000–01) and the routine-use era (2004–14) and defined vaccine effectiveness as 1 minus the incidence rate ratio, expressed as a percentage.Findings40 482 children younger than 13 years resident in KHDSS were admitted to KCH between 2000 and 2014, 38 206 (94%) of whom had their blood cultured. The incidence of invasive H influenzae type b disease in children younger than 5 years declined from 62·6 (95% CI 46·0–83·3) per 100 000 in 2000–01 to 4·5 (2·5–7·5) per 100 000 in 2004–14, giving a vaccine effectiveness of 93% (95% CI 87–96). In the final 5 years of observation (2010–14), only one case of invasive H influenzae type b disease was detected in a child younger than 5 years. Nasopharyngeal H influenzae type b carriage was detected in one (0·2%) of 623 children younger than 5 years between 2009 and 2012. In the 2009 serosurvey, 92 (79%; 95% CI 70–86) of 117 children aged 4–35 months had long-term protective antibody concentrations.InterpretationIn this region of Kenya, use of a three-dose primary series of Hib vaccine without a booster dose has resulted in a significant and sustained reduction in invasive H influenzae type b disease. The prevalence of nasopharyngeal carriage is low and the profile of Hib antibodies suggests that protection wanes only after the age at greatest risk of disease. Although continued surveillance is important to determine whether effective control persists, these findings suggest that a booster dose is not currently required in Kenya.FundingGavi, the Vaccine Alliance, Wellcome Trust, European Society for Paediatric Infectious Diseases, and National Institute for Health Research.

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“…Both natural exposure to Hib and administration of Hib conjugate vaccine elicit robust anti-PRP antibodies. A threshold of anti-PRP antibody required for short-term protection has been established as >0.15 µg/mL, and long-term protection at >1 µg/mL [ 15 ]. Two studies have assessed anti-PRP antibody levels in Nepal to evaluate disease susceptibility.…”

Section: Discussionmentioning

confidence: 99%

Impact of Vaccination on Haemophilus influenzae Type b Carriage in Healthy Children Less Than 5 Years of Age in an Urban Population in Nepal

Shrestha

Stockdale

Gautam

et al. 2021

The Journal of Infectious Diseases

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Background Reduction in detection of asymptomatic carriage of Haemophilus influenzae type b (Hib) can be used to assess vaccine impact. In Nepal, routine vaccination against Hib in children at 6, 10, and 14 weeks of age was introduced in 2009. Before vaccine introduction, Hib carriage was estimated at 5.0% among children aged <13 years in Nepal, with higher rates among children under 5. Large-scale evaluation of Hib carriage in children has not been investigated since the introduction of the pentavalent diphtheria-tetanus-pertussis/Hib/hepatitis B (DTP-Hib-HepB) vaccine in Nepal. Methods A total of 666 oropharyngeal swabs were collected between August and December 2018 from healthy children between 6 months and 5 years of age attending the vaccination clinic at Patan Hospital, Kathmandu, Nepal. Of these 666 swabs, 528 (79.3%) were tested for Hib by culture. Demographic and vaccination data were collected. Results Among 528 swabs tested for Hib, 100% came from fully vaccinated children. No swabs were positive for Hib (95% confidence interval, .0–.7). The absence of Hib in 2018 suggests vaccine-induced protection against Hib carriage 9 years after vaccine introduction. Conclusions Following 3 doses of pentavalent DTP-Hib-HepB vaccine, Hib carriage in children under the age of 5 years in Nepal is no longer common. Ongoing high coverage with Hib vaccine in early childhood is expected to maintain protection against Hib disease in Nepal.

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Evaluation of Haemophilus influenzae Type b Vaccine for Routine Immunization in Nepali Infants

Abstract: Immunization with HibCV given as part of the Expanded Program on Immunization schedule in Nepal elicits robust antibody responses. Though the antibody wanes during the first year of life, most 1-year-old infants remain protected and respond robustly to a booster dose of the vaccine.

Cited by 6 publications

References 27 publications

Impaired Haemophilus influenzae Type b Transplacental Antibody Transmission and Declining Antibody Avidity through the First Year of Life Represent Potential Vulnerabilities for HIV-Exposed but -Uninfected Infants

Impaired Haemophilus influenzae Type b Transplacental Antibody Transmission and Declining Antibody Avidity through the First Year of Life Represent Potential Vulnerabilities for HIV-Exposed but -Uninfected Infants

Effect of Haemophilus influenzae type b vaccination without a booster dose on invasive H influenzae type b disease, nasopharyngeal carriage, and population immunity in Kilifi, Kenya: a 15-year regional surveillance study

Impact of Vaccination on Haemophilus influenzae Type b Carriage in Healthy Children Less Than 5 Years of Age in an Urban Population in Nepal

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