Immunogenicity of a 7-valent pneumococcal conjugate vaccine (PCV7) and impact on carriage in Venezuelan children at risk of invasive pneumococcal diseases

Vaccination coverage of children with chronic diseases is inadequate especially for specifically recommended vaccines

AIM

Our objectives were to measure the vaccine coverage rates for children with chronic diseases as well as the prevalence of potentially harmful delays for generally recommended vaccines. We also identified the factors influencing non-adherence to vaccines specifically recommended for chronic conditions.

METHODS

Three non-interventional point-prevalence surveys were performed in 2014 in all paediatric units at Lille University Hospital among children aged 2 months-18 years with chronic diseases and vaccination data. Vaccine coverage and delays for generally recommended vaccines were studied. The children who were up-to-date and those under-vaccinated for specifically indicated vaccines were compared and the factors potentially associated with under-vaccination were studied with multivariable analysis.

RESULTS

We screened 682 patients: of 207 with chronic diseases, mainly neurological, muscular and respiratory disorders, 146 had vaccination data. Only 47% (95% confidence interval 39-55) were up-to-date for all generally recommended vaccinations; potentially harmful vaccination delays were high (26%-75%). Only 11% of the 81% of patients for whom some vaccines were specifically recommended were up-to-date. Low maternal education level was significantly associated with under-vaccination (adjusted odds ratio 10.5, 95% confidence interval 1.3-86.9, P = .03).

CONCLUSION

This study showed inadequate vaccine coverage rates and significant delays among children with chronic diseases.

Impact of pneumococcal conjugate vaccine on the carriage density of Streptococcus pneumoniae and Staphylococcus aureus in children living with HIV: a nested case-control study

Nasopharyngeal colonization density of Streptococcus pneumoniae (pneumococcus) is associated with disease severity and transmission. Little is known about the density of pneumococcal carriage in children with HIV (CLH). Pneumococcal vaccines may impact the density of pneumococcus and competing microbes within the nasopharynx. We examined the impact of one dose of PCV13 on carriage density of pneumococcus and Staphylococcus aureus, in CLH, HIV-uninfected children (HUC), and their unvaccinated parents. We conducted a pilot-nested case-control study, within a larger prospective cohort study, on the impact of PCV13, in families in West Bengal India. Quantitative real-time PCR was run on 147 nasopharyngeal swabs from 27 CLH and 23 HUC, and their parents, before and after PCV13 immunization. CLH had higher median pneumococcal carriage density, compared to HUC: 6.28 × 108 copies/mL vs. 2.11 × 105 copies/mL (p = .005). Following one dose of PCV13, pneumococcal densities dropped in both groups, with an increase in S. aureus carriage to 80% from 48% in CLH, and to 60% in HUC from 25%. While limited in sample size, this pilot study shows that CLH carried higher densities of pneumococcus. PCV13 was associated with a decrease in pneumococcal density and a temporal increase in S. aureus carriage regardless of HIV status.

Pneumococcal Nasopharyngeal Carriage in Young Healthy Children After Pneumococcal Conjugate Vaccine in Turkey

AIMS

To determine the prevalence of nasopharyngeal carriage of Streptococcus pneumoniae in healthy children aged 0-6 years who were vaccinated with pneumococcal conjugate vaccine.

METHODS

This cross-sectional study was conducted on 150 healthy Turkish children between 1 month and 6 years of age. Serotyping was performed and risk factors of carriage were evaluated.

RESULTS

The overall carriage rate was 14%. Vaccine type serotypes were determined in 17 (12.6%) children who received full-dose PCV13 vaccine. The highest carriage rate was observed among children younger than 24 months (76.2%). In multivariate analysis, respiratory infection in recent months, age, attendance at a day-care center and antibiotic usage were not statistically significant risk factors for carriage. Overall, S. pneumoniae strains were considered as penicillin susceptible and antimicrobial resistance was limited.

CONCLUSION

We observed a low rate of pneumococcal carriage in children after PCV13 implementation compared with that of children receiving PCV7. Although it was reduced, vaccine serotype colonization in PCV13-vaccinated children remains persistent.

Nasopharyngeal Pneumococcal Colonization and Impact of a Single Dose of 13-Valent Pneumococcal Conjugate Vaccine in Indian Children With HIV and Their Unvaccinated Parents

BACKGROUND

Human immunodeficiency virus (HIV) infection increases risk of invasive disease from Streptococcus pneumoniae. Pneumococcal conjugate vaccines (PCV) prevent invasive disease and acquisition of vaccine type (VT) pneumococcus in the nasopharynx.

OBJECTIVE

To look at the safety and impact of one dose of PCV13 on acquisition of VT pneumococcal carriage in Indian children with HIV.

METHOD

We conducted a cohort study in families of HIV-infected children (CLH) and families of HIV-uninfected children (HUC) in West Bengal. All children received one dose of PCV13. Nasopharyngeal swabs were collected from children and parents at baseline and 2 months after vaccination.

RESULT

One hundred and fifteen CLH and 47 HUC received one dose of PCV13. Fifty-eight percent of CLH were on antiretroviral therapy (ART), and the median nadir CD4 count was 287. There were no significant adverse events in either group. HUC had more VT colonization than CLH-55% versus 23% of all pneumococcal isolates. HIV infection doubled the risk of nonvaccine serotype colonization (P = 0.03). There was no difference in acquisition of VT isolates in CLH (4.4%) and HUC (4.5%) post-PCV13; however, older CLH (>5 years) had decreased clearance of VT strains. ART made no difference in pneumococcal colonization at baseline or after PCV13; however, CLH with higher nadir CD4 counts before starting ART were less likely to have VT colonization post-PCV13 (prevalence ratio, 0.2; 95% confidence interval: 0.1-0.5).

CONCLUSION

While there was no difference in acquisition of VT nasopharyngeal carriage of pneumococcus in CLH and HUC after one dose of PCV13, earlier access to ART may impact response to PCV13 in CLH.

A phase III observer-blind randomized, controlled study to evaluate the immune response and the correlation with nasopharyngeal carriage after immunization of university students with a quadrivalent meningococcal ACWY glycoconjugate or serogroup B meningococcal vaccine

BACKGROUND

University students have high rates of pharyngeal carriage of Neisseria meningitidis. Interruption of carriage acquisition is an important mechanism of vaccines for inducing herd protection. 4CMenB and MenACWY-CRM vaccines have been shown to be immunogenic against meningococcal serogroups B and ACWY respectively in younger age groups, and also to elicit a modest impact on meningococcal carriage in vaccinated students. However, vaccine responses in university students and the impact of serum bactericidal antibody (SBA) titers on meningococcal carriage are undetermined.

METHODS

Immunogenicity of two 4CMenB doses or one MenACWY-CRM dose was measured in university students at Months 2, 4, 6 and 12 post-first vaccination. Immunogenicity of one MenACWY-CRM dose in students with previous meningococcal serogroup C conjugate vaccination was also assessed. Immune responses were measured with an SBA assay using human complement (hSBA) against three reference strains for serogroup B and against one strain for each for serogroups C and Y. Correlations between hSBA titers and meningococcal carriage were analyzed.

RESULTS

All subjects demonstrated robust functional antibody responses to both vaccines at Month 2 and a high proportion maintained protective hSBA titers up to Month 12. At baseline, carriage of disease-associated serogroup B strains and serogroups C and Y were higher in subjects with already-protective hSBA titers. Post-vaccination, while both 4CMenB and MenACWY-CRM elicited robust immunogenicity in students, significant correlations between post-vaccination hSBA titers and carriage of disease-associated serogroups were not observed.

CONCLUSIONS

4CMenB and MenACWY-CRM were both highly immunogenic. There was no correlation between carriage and post-vaccination hSBA titers.

Serotype distribution and penicillin-non-susceptibility of Streptococcus pneumoniae causing invasive diseases in Kuwait: A 10-year study of impact of pneumococcal conjugate vaccines

OBJECTIVES

The impact of PCV7 and PCV13 on pneumococcal infections in Kuwait is not known. Therefore we evaluated the impact on pneumococcal serotype distribution and penicillin-non-susceptibility in invasive infections in Kuwait.

METHODS

Children < 2 y were given PCV7 from Aug 2006 to Jul 2010 (period I), and PCV13 from Aug 2010 to Jul 2013 (period II) with a pre-vaccination period from Aug 2003 to Jul 2006. Serotype and penicillin-non-susceptibility of blood and cerebrospinal fluid isolates from all ages were determined.

RESULTS

In <2 y old children, even with a small number of infections, a drop in PCV7 serotypes was evident after vaccination. For all age groups combined, in the pre-vaccination period, PCV7, PCV13, PCV13 non-PCV7 serotypes and penicillin-non-susceptibility constituted 53.2%, 72.6%, 19.4% and 6.5% of the isolates respectively. PCV7, PCV13 non-PCV7 serotypes and penicillin-non-susceptibility changed to 32.7%, 28.2% and 7.3% (period I) and 6.6%, 22.2% and 8.9% (period II).

CONCLUSIONS

Vaccines reduced invasive infections due to PCV7 serotypes.