Effect of Haemophilus influenzae Type b Vaccination on Nasopharyngeal Carriage Rate in Children, Tehran, 2019

Abstract

Background. Haemophilus influenzae (H. influenzae) strains, which commonly reside as commensals within the human pharynx and can remain as an asymptomatic carrier, but become invasive leading to pneumonia, septic arthritis, or meningitis. The Pentavac (pentavalent vaccine, manufactured by India, SII (DTwP-HepB-Hib)) was introduced to the Iranian National Immunization Plan in November 2014. The aim of this study is to investigate H. influenzae type b (Hib) carrier rate among children under 6 years old in Tehran. Methods. This cross-sectional study was performed on 902 children including vaccinated/unvaccinated in the age of 6 months to 6 years, in Tehran. Sampling was performed from July 2019 to September 2019. Nasopharyngeal samples were taken from children by sterile swab. The PCR method was used to extract DNA. Then, all H. influenzae isolates were initially confirmed by molecular tests. BexA was used to distinguish typeable H. influenzae strains from nontypeable Haemophilus influenzae (NTHi). Results. A total of 902 children were enrolled in the study: 452 were female (51%). H. influenzae carriage rate was 267 (29%), of that 150 samples (16.6%) were typeable. The nasopharyngeal Hib carrier rate in the children was 2.6% (24/902). 262 cases did not receive Hib vaccine. Analysis in nonnursery’s children aged 4 to 6 (unvaccinated) years showed that the lower educational level of father, mother, and family number correlated with increased odds of colonization of children with Hib. Conclusion. Our findings showed a significant decrease (60%) in the overall Hib nasopharyngeal carriage in healthy children under six years after 5 years after the start of Hib vaccination.

Multiplex polymerase chain reaction detection of Streptococcus pneumoniae and Haemophilus influenzae and their antibiotic resistance in patients with community-acquired pneumonia from southwest Iran

“…In November 2014, the pentavalent vaccine which contains diphtheria, tetanus, whole cell pertussis, hepatitis B, and H. influenzae type b entered the Iranian National Immunization Plan. Vaccination against Hib may reduce Hib colonization, while increasing other serotypes [ 8 , 34 ] The technique used to identify the H. influenzae capsular type may affect the results. Because in some studies, slide agglutination serotyping-based methods and in some others the molecular methods are used [ 33 ].…”

“…This Gram-negative bacterium exists in two forms: encapsulated (typeable) and unencapsulated (non-typeable) H. influenzae (NTHi) [ 6 , 7 ]. Encapsulated H. influenzae includes 6 serotypes a, b, c, d, e and f [ 8 – 10 ]. H. influenzae type b (Hib) is a prevalent cause of serious illness, practically in children under the age of 5 years.…”

Characteristics of Haemophilus influenzae carriage among healthy children in China: A meta-analysis

“…Since 2014—when Hib was included in Iran routine immunization program—and as of 2019, Hi has been detected in 267 of 902 healthy children in Tehran, Iran, with a carriage rate of 29%. [ 33 ] Among 565 healthy children in Rochester, New York, the Hi carriage rate was 5.9% in 2020. [ 34 ] Currently, the Hib vaccination is voluntary in China.…”

Pattern of Lipid nanoparticle (LNP)- RNA vaccine against Haemophilus influenza type b hcsA and hcsB genes facilitating the transport of capsular polysaccharides across the outer membrane

“…So far, this approach requires no specialized tools or radiolabeling and is almost as delicate as a radioimmunoassay (RIA). 14 The method known as "fluorescence-activated cell sorting" (also known as "flow cytometry") is used to describe the variety of immunologically active humoral cell types. If tracking the quantity of helper T cells is necessary, patient cells are tagged with monoclonal antibodies directed against proteins unique to the cells of interest, such as CD4 protein.…”