Haemophilus influenzae type b infection, vaccination, and H. influenzae carriage in children in Minnesota, 2008-2009

Vaccination in Pediatric Patients with Sickle-Cell Disease: Uptake Report and Mini-Review

BACKGROUND

Brazil has one of the highest numbers of births with sickle-cell disease (SCD) in the Americas. Despite the risk of severe illnesses and death due to both vaccine-preventable infections, vaccination uptake in pediatric patients with SCD is unknown.

MATERIAL AND METHODS

Children under 18 years with SCD presenting to routine medical consultations had their vaccination status evaluated according to the national recommendations. Data obtained were classified as 'Adequate', 'Delayed' or 'Missing' vaccination and compared among age groups.

RESULTS

From 117 children screened, 100 had their vaccination card available. Vaccination coverage of routine vaccines was above 95% for all primary series and both age groups, with varied rates of delays and low missing doses. Among SCD extended vaccination, the most frequently delayed and missed vaccines were those specifically recommended to individuals with SCD as per national guidelines-and particularly those against encapsulated bacteria. Significant and varied rates of missing doses occurred in primary series and booster doses for PPSV23, Hib, menC, hepatitis A and varicella. The average influenza vaccination rate was 69.5%, with higher rates among younger children.

CONCLUSIONS

Children with SCD have alarming under-vaccination rates. Basic prevention strategies in Brazil should be reassessed in this specific population.

Nasopharyngeal carriage of Haemophilus influenzae among adults with co-morbidities

After the widespread use of Haemophilus influenzae type b (Hib) vaccine, H. influenzae invasive disease is now commonly due to non-encapsulated (NTHi), affecting mostly the youngest and the elderly. The objective of this study was to investigate H. influenzae nasopharyngeal carriage rate in adults with co-morbidities and possible associated risk factors.

METHODS

Patients aged >50 years with co-morbidities attending medical centres were examined. A nasopharyngeal swab was analysed for H. influenzae presence by cultural and molecular methods (RT-PCR). Univariable and multivariable analysis of risk factors for H. influenzae carriage were performed. Serotype of isolates was determined by PCR capsular genotyping. Minimum inhibitory concentration (MIC) was determined by MIC gradient test and β-lactamase production was detected by the nitrocephin test. Genotyping was performed by Multilocus sequence typing (MLST). Phylogenetic relationships among carriage and invasive NTHi strains were assessed.

RESULTS

Among 248 enrolled patients (median age: 73 years), the carriage rate was 5.6% and 10.5% by cultural method or RT-PCR, respectively. Colonization with H. influenzae was significantly associated with the presence of acute respiratory symptoms (adjusted OR = 12.16, 95% CI: 3.05-48.58, p < 0.001). All colonizing isolates were NTHi. Three isolates (3/14, 21.4%) were resistant to ampicillin and beta-lactamase positive. MLST revealed a high degree of genetic diversity, with 11 different STs from 14 isolates. Eight out of the 11 (72.7%) STs were shared among carriage and invasive isolates.

CONCLUSIONS

Adults ≥50 years old with co-morbidities are occasionally colonized by H. influenzae, even if the presence of co-morbidities is not a risk factor for colonization. The presence of acute respiratory symptoms is the only factor associated with H. influenzae colonization. Colonizing H. influenzae are all NTHi. Colonizing H. influenzae often belong to the same STs of invasive disease isolates.

The pharyngeal carriage of Haemophilus influenzae among healthy population in China: a systematic review and meta-analysis

BACKGROUND

A nationwide investigation on the carriage proportion of H. influenzae among healthy populations is lacking in China. The purpose of the study was to review the prevalence of pharyngeal carriage of H. influenzae among healthy populations in China, and explore its influencing factors. The serotypes distribution of H. influenzae was also analyzed.

METHODS

A systematic search was conducted with key words "Haemophilus influenzae", "Carriage", and "China" or "Chinese" from inception to March 2018. After careful screening, the data of included articles were extracted with a pre-designed excel form. Then, the pooled carriage proportion of H. influenzae was calculated using the random effect model.

RESULTS

A total of 42 studies with 17,388 participants were included. The overall pooled carriage proportion of H. influenzae was 0.17 (95% CI: 0.13-0.21), and the carriage proportion largely varied by province. Subgroup analysis indicated that the pooled carriage proportion was 0.17 (0.13-0.21) for children, and 0.14 (0.7-0.23) for adults. There were no statistically significant heterogeneity between subgroups by age (p = 0.65), sex (p = 0.88), and season (p = 0.10). The pooled carriage proportion of Hib was 0.01 (0-0.02), while the carriage proportion of NTHi was 0.22 (0.13-0.31).

CONCLUSION

In China, the carriage proportion of H. influenzae among healthy population was low, but it largely varied by provinces.

Are we speaking the same language? an argument for the consistent use of terminology and definitions for childhood vaccination indicators

Vaccination indicators are used to measure the health status of individuals or populations and to evaluate the effectiveness of vaccination programs or policies. Ensuring that vaccination indicators are clearly and consistently defined is important for effective communication of outcomes, accurate program evaluation, and comparison between different populations, times, and contexts. The purpose of this commentary is to describe commonly used vaccination indicators and to highlight inconsistencies in how childhood vaccine researchers use and define these terms. The indicators we describe are vaccine coverage, uptake, and rate; vaccination status, initiation, and completion; and up-to-date, timely, partial, and incomplete vaccination. We conclude that many vaccination indicators are not explicitly defined within published research studies and/or are used quite differently across studies. We also note that the choice of indicator in a given study is often driven by program or vaccine specific factors, may be constrained by data availability, and should be chosen to best reflect the outcome of interest. We conclude that the use of consistent language and definitions would promote more effective communication of research findings. We also propose some standardized definitions for common indicators, with the goal of provoking discussion and debate on the issue.

A nationwide population-based surveillance of invasive Haemophilus influenzae diseases in children after the introduction of the Haemophilus influenzae type b vaccine in Japan

BACKGROUND

Haemophilus influenzae type b (Hib) vaccine was introduced as a voluntary vaccine in December 2008 and was included in the national routine immunization program in April 2013 in Japan. Currently, no nationwide data are available to evaluate the effectiveness of Hib vaccine in Japan.

METHODS

To evaluate the effectiveness of Hib vaccine in Japan, nationwide active population-based surveillance of culture-proven invasive infections caused by H. influenzae in children was performed in 2008-2017 in 10 prefectures in Japan (covering approximately 23% of the total Japanese population). Clinical data were recorded on a standardized case report form. Capsular type and antimicrobial susceptibility of the H. influenzae isolates were examined. The incidence rate ratio (IRR) and its confidence interval (CI) were calculated to compare data from 5 years before and that from after the introduction of the national routine Hib vaccine immunization program.

RESULTS

During the 10-year study period, 566 invasive H. influenzae disease cases including 336 meningitis cases were identified. The average number of invasive H. influenzae disease cases among children <5 years of age during 2013-2017 decreased by 93% (IRR: 0.07, 95%CI 0.05-0.10, p < 0.001) compared with those occurring during 2008-2012. Hib strains have not been isolated from invasive H. influenzae disease cases since 2014; however, non-typeable H. influenzae and H. influenzae type f isolates have been noted as causes of invasive H. influenzae diseases among children <5 years in the post-Hib vaccine era.

CONCLUSIONS

After the governmental subsidization of the Hib vaccine, invasive Hib disease cases decreased dramatically in the study population, as per our surveillance. Continuous surveillance is necessary to monitor the effectiveness of Hib vaccine and for detecting any emerging invasive capsular types.

Haemophilus influenzae Type b Invasive Disease in Amish Children, Missouri, USA, 2014

During 5 months in 2014, three Amish children in Missouri, USA, were diagnosed with invasive Haemophilus influenzae type b infection. Two were rural neighbors infected with a genetically similar rare strain, sequence type 45. One child had recently traveled, raising the possibility of maintenance of this strain among unvaccinated carriers in Amish communities.

Cultivation of an Adaptive Domestic Network for Surveillance and Evaluation of Emerging Infections

Accomplishments of this program have provided numerous dividends and might benefit areas outside infectious diseases.

Evaluation of Haemophilus influenzae type b carrier status among children 10 years after the introduction of Hib vaccine in Brazil

The aim of the present study was to assess the prevalence of Haemophilus influenzae type b (Hib) nasopharyngeal (NP) colonisation among healthy children where Hib vaccination using a 3p+0 dosing schedule has been routinely administered for 10 years with sustained coverage (> 90%). NP swabs were collected from 2,558 children who had received the Hib vaccine, of whom 1,379 were 12-< 24 months (m) old and 1,179 were 48-< 60 m old. Hi strains were identified by molecular methods. Hi carriage prevalence was 45.1% (1,153/2,558) and the prevalence in the 12-< 24 m and 48-< 60 m age groups were 37.5% (517/1,379) and 53.9% (636/1,179), respectively. Hib was identified in 0.6% (16/2,558) of all children in the study, being 0.8% (11/1,379) and 0.4% (5/1,179) among the 12-< 24 m and 48-< 60 m age groups, respectively. The nonencapsulate Hi colonisation was 43% (n = 1,099) and was significantly more frequent at 48-< 60 m of age (51.6%, n = 608) compared with that at 12-< 24 m of age (35.6%, n = 491). The overall resistance rates to ampicillin and chloramphenicol were 16.5% and 3.7%, respectively; the co-resistance was detected in 2.6%. Our findings showed that the Hib carrier rate in healthy children under five years was very low after 10 years of the introduction of the Hib vaccine.

The incidence of pediatric invasive Haemophilus influenzae and pneumococcal disease in Chiba prefecture, Japan before and after the introduction of conjugate vaccines

The Haemophilus influenzae type b (Hib) vaccine and the heptavalent pneumococcal conjugate vaccine (PCV7) were introduced in Japan in 2008 and 2010, respectively. In 2011, immunization with these two vaccines was encouraged throughout Japan through a governmental program. Children treated in Chiba prefecture for culture-proven invasive H. influenzae disease (IHiD) and invasive Streptococcus pneumoniae disease (IPD) were identified in a prefectural surveillance study from 2008 to 2013. The incidence rate ratio (IRR) and its confidence interval (CI) were calculated to compare the 3 years before and after governmental financial support for vaccination. The average number of IHiD and IPD cases among children <5 years of age in 2011-2013 decreased 84% (IRR: 0.16, 95% CI: 0.09-0.26, p<0.0001) and 51% (IRR: 0.49, 95% CI: 0.37-0.63, p<0.0001) compared with those occurring in 2008-2010. The most common non-PCV7 serotype encountered in 2011 and 2013 was 19A. After governmental subsidization of Hib and PCV7 vaccination, IHiD and IPD decreased in Chiba prefecture, Japan. Continuous surveillance is necessary to determine the effectiveness of these two vaccines and for detection of emerging invasive serotypes.

Invasive Haemophilus influenzae Disease in Adults ≥65 Years, United States, 2011

In this older age group burden of disease and CFR both increase significantly as age increases. Several underlying conditions increased risk of disease severity and patients with severe disease were more likely to die.

Background

 Since the introduction of the Haemophilus influenzae serotype b vaccine, H influenzae epidemiology has shifted. In the United States, the largest burden of disease is now in adults aged ≥65 years. However, few data exist on risk factors for disease severity and outcome in this age group.

Methods

 A retrospective case-series review of invasive H influenzae infections in patients aged ≥65 years was conducted for hospitalized cases reported to Active Bacterial Core surveillance in 2011.

Results

 There were 299 hospitalized cases included in the analysis. The majority of cases were caused by nontypeable H influenzae, and the overall case fatality ratio (CFR) was 19.5%. Three or more underlying conditions were present in 63% of cases; 94% of cases had at least 1. Patients with chronic heart conditions (congestive heart failure, coronary artery disease, and/or atrial fibrillation) (odds ratio [OR], 3.27; 95% confidence interval [CI], 1.65–6.46), patients from private residences (OR, 8.75; 95% CI, 2.13–35.95), and patients who were not resuscitate status (OR, 2.72; 95% CI, 1.31–5.66) were more likely to be admitted to the intensive care unit (ICU). Intensive care unit admission (OR, 3.75; 95% CI, 1.71–8.22) and do not resuscitate status (OR, 12.94; 95% CI, 4.84–34.55) were significantly associated with death.

Conclusions

 Within this age group, burden of disease and CFR both increased significantly as age increased. Using ICU admission as a proxy for disease severity, our findings suggest several conditions increased risk of disease severity and patients with severe disease were more likely to die. Further research is needed to determine the most effective approach to prevent H influenzae disease and mortality in older adults.

Invasive Haemophilus influenzae serotype e and f disease, England and Wales

Incidence of serotype e was 3-fold lower than serotype f, but it caused more severe clinical disease.

Haemophilus influenzae type b disease and vaccine booster dose deferral, United States, 1998-2009

BACKGROUND

Since the introduction of effective vaccines, the incidence of invasive Haemophilus influenzae type b (Hib) disease among children <5 years of age has decreased by 99% in the United States. In response to a limited vaccine supply that began in 2007, Hib booster doses were deferred for 18 months.

METHODS

We reviewed national passive and active surveillance (demographic and serotype) and vaccination status data for invasive H. influenzae disease in children aged <5 years before (1998-2007) and during (2008-2009) the vaccine shortage years to assess the impact of the vaccine deferral on Hib disease. We estimated the average annual number of Hib cases misclassified as unknown (not completed or missing) serotype.

RESULTS

From 1998 to 2007 and 2008 to 2009, the annual average incidence of Hib disease per 100000 population was 0.2 and 0.18, respectively; no significant difference in incidence was found by age group, gender, or race. Among Hib cases in both time periods, most were unvaccinated or too young to have received Hib vaccine. During 2001 to 2009, there were <53 Hib cases per year, with an estimated 6 to 12 Hib cases misclassified as unknown serotype.

CONCLUSIONS

The booster deferral did not have a significant impact on the burden of invasive Hib disease in children <5 years of age. Continued surveillance and serotype data are important to monitor changes in Hib incidence, especially during vaccine deferrals. Hib booster deferral is a reasonable short-term approach to a Hib vaccine shortage.

Evaluation of new biomarker genes for differentiating Haemophilus influenzae from Haemophilus haemolyticus

PCR detecting the protein D (hpd) and fuculose kinase (fucK) genes showed high sensitivity and specificity for identifying Haemophilus influenzae and differentiating it from H. haemolyticus. Phylogenetic analysis using the 16S rRNA gene demonstrated two distinct groups for H. influenzae and H. haemolyticus.

Genome sequences for five strains of the emerging pathogen Haemophilus haemolyticus

We report the first whole-genome sequences for five strains, two carried and three pathogenic, of the emerging pathogen Haemophilus haemolyticus. Preliminary analyses indicate that these genome sequences encode markers that distinguish H. haemolyticus from its closest Haemophilus relatives and provide clues to the identity of its virulence factors.

Haemophilus influenzae type b carriage among young children in metropolitan Atlanta in the context of vaccine shortage and booster dose deferral

Short-term deferral of the Haemophilus influenzae type b (Hib) vaccine booster dose during a recent U.S. Hib vaccine shortage did not result in widespread Hib carriage in Atlanta, as the Hib carriage rate was found to be 0.3% (1/342). Hib colonization was significantly more common among males and day care attendees.