Quantitative Analysis of the Instant and Persistent Inhibition Effects of Maternal Poliovirus Antibodies on the Immune Response in a Phase IV Trial of a Sabin Strain-Based Inactivated Poliovirus Vaccine

BACKGROUND

An inactivated poliomyelitis vaccine made from Sabin strains (sIPVs) has widely been used in China since 2015. However, the quantitative data on the instant and persistent inhibition effects of maternal poliovirus antibodies on the immune response to sIPV priming and booster vaccination have not been available yet.

OBJECTIVE

In this study, we aim to explore and quantify the instant and persistent inhibition effect of maternal poliovirus antibodies on the immune response elicited by sIPV primary and booster vaccination.

METHODS

The immunogenicity data consisting of the days 0 and 30 after the prime and booster vaccination of the sIPV in a phase IV trial were pooled for a quantitative analysis of the inhibition effect of maternal poliovirus antibody. The geometric mean ratio (GMR) was calculated using linear regression models, representing that every 2-fold higher maternal poliovirus antibody titer may result in a (1-GMR) lower postimmunization antibody titer.

RESULTS

The GMRs for poliovirus types 1, 2, and 3 were 0.79 (0.77-0.82), 0.85 (0.81-0.89), and 0.87 (0.83-0.91) at 30 days after the priming series, 0.86 (0.83-0.89), 0.81 (0.76-0.85), and 0.86 (0.80-0.93) at one year after the priming series, and 0.96 (0.94-0.99), 0.89 (0.86-0.93), and 0.98 (0.93-1.03) at 30 days after the booster dose. The inhibition effect continued to exist until the booster dose 1 year later, and such a persistent inhibition effect was almost attenuated for poliovirus types 1 and 3, and partly reduced for type 2 at 30 days after the booster dose.

CONCLUSION

A wider interval between the four sIPV doses might be a consideration for reducing the effect of maternal antibodies and subsequently eliciting and maintaining higher antibody levels to protect against poliovirus transmission and infection at the final stage of polio eradication in the global world. This study's clinical trial registry number is NCT04224519.

COVID-19 pandemic impact on primary immunization uptake

Purpose/Background

Pediatricians across the world are seeing a steep drop in the number of children coming in for appointments due to COVID-19 pandemic. To prevent outbreaks of serious diseases that pose an even greater threat to children than COVID-19, it is important that children not skip their routine vaccines. The aim of this study was to determine the impact of COVID-19 pandemic on primary immunization activities in Saudi Arabia.

Settings and Design

Cross-sectional design.

Methods and Material

The study was conducted at a community pediatric clinic. All parents of preschool-age children who visited the community pediatric clinics were asked to complete a self-administrated questionnaire on primary immunization uptake during the pandemic.

Statistical Analysis Used

The Chi-square and Fisher's exact test were performed to examine the demographic differences between participants who missed vaccination during the pandemic and reasons for missing the vaccination.

Results

Three hundred study participants completed our questionnaire. In total, 90.6% of respondents were up to date with their vaccinations prior to the pandemic, and most respondents believed that children should be immunized at an appropriate age, it is essential for children to be fully immunized, vaccination is effective in preventing serious disease, and childhood immunization is essential during the pandemic (98.3%, 98.7%, 97.3%, and 93.7%, respectively). In total, 72.4% of respondents did not miss their vaccinations during the pandemic, while 26.6% missed vaccinations. The most common reason for missing vaccinations during the pandemic was transportation difficulty and curfew, followed by fear of contracting COVID-19 infection (40.9% and 35.5%, respectively). Those who did not believe that childhood immunization was necessary during the pandemic were more likely to miss vaccinations during the pandemic (P < 0.001). In addition, those who did not have a family member with COVID-19 infection were more likely not to miss the vaccine (P < 0.001). Moreover, those who thought taking vaccinations in a primary care setting or hospital is safe were more likely not to miss the vaccination during the pandemic (P < 0.027) and (P < 0.001).

Conclusions

Significant portion of the population was affected and missed immunizations during the pandemic. The perceptions on the importance of immunization and having a family member affected with COVID-19 during the pandemic were important factors in missing immunizations. Moreover, transportation and fear of contracting COVID-19 during the curfew were also common reasons for missing immunizations during the pandemic.

Recent Advances in the Use of Galleria mellonella Model to Study Immune Responses against Human Pathogens

The use of invertebrates for in vivo studies in microbiology is well established in the scientific community. Larvae of Galleria mellonella are a widely used model for studying pathogenesis, the efficacy of new antimicrobial compounds, and immune responses. The immune system of G. mellonella larvae is structurally and functionally similar to the innate immune response of mammals, which makes this model suitable for such studies. In this review, cellular responses (hemocytes activity: phagocytosis, nodulation, and encapsulation) and humoral responses (reactions or soluble molecules released in the hemolymph as antimicrobial peptides, melanization, clotting, free radical production, and primary immunization) are discussed, highlighting the use of G. mellonella as a model of immune response to different human pathogenic microorganisms.

Timeliness of Childhood Primary Immunization and Risk Factors Related with Delays: Evidence from the 2014 Zhejiang Provincial Vaccination Coverage Survey

Background: this study aimed to assess both immunization coverage and timeliness, as well as reasons for non-vaccination, and identity the risk factors of delayed immunization, for the vaccines scheduled during the first year of life, in Zhejiang province, east China. Methods: A cluster survey among children aged 24-35 months was conducted. Demographic information and socio-economic characteristics of the selected child, the mother, and the household were collected. Immunization data were transcribed from immunization cards. Timeliness was assessed with Kaplan-Meier analysis for each vaccine given before 12 months of age, based on the time frame stipulated by the expanded program on immunization of China. Cox proportional hazard regression was applied to identify risk factors of delayed immunization. Results: A total of 2772 eligible children were surveyed. The age-appropriate coverage ranged from 25.4% (95% CI: 23.7-27.0%) for Bacillus Calmette-Guerin (BCG) to 91.3% (95% CI: 90.2-92.3%) for the first dose of oral poliomyelitis vaccine (OPV1). The most frequent reason for non-vaccination was parent's fear of adverse events of immunization. Delayed immunizations were associated with mother having a lower education level, mother having a job, delivery at home, increasing number of children per household, and having a lower household income. Conclusions: Although the timeliness of immunization has improved since 2011, necessary steps are still needed to achieve further improvement. Timeliness of immunization should be considered as another important indicator of expanded program on immunization (EPI) performance. Future interventions on vaccination coverage should take into consideration demographic and socio-economic risk factors identified in this study. The importance of adhering to the recommended schedule should be explained to parents.

Novel Intervention in the Aging Population: A Primary Meningococcal Vaccine Inducing Protective IgM Responses in Middle-Aged Adults

Introduction

Vaccine responses are often reduced in the elderly, leaving part of the elderly population vulnerable to infectious diseases. Timely vaccination may offer a solution for strengthening memory immunity before reaching old age, which classifies middle-aged persons as a target age group for vaccine interventions. However, knowledge regarding the immunogenicity of primary immunizations in middle-aged adults is lacking. We determined the immunogenicity of a primary meningococcal vaccine towards which no or (very) low pre-vaccination immunity exists in middle-aged adults (NTR4636).

Methods

A vaccine containing multiple meningococcal groups (tetravalent) conjugated to tetanus toxoid (MenACWY-TT) was administered to middle-aged adults (50–65 years of age, N = 204) in a phase IV single-center and open-label study. Blood samples were taken pre-, 7 days, 28 days, and 1 year post-vaccination. Functional antibody titers were measured with the serum bactericidal assay (SBA). Meningococcal- and tetanus-specific antibody responses were determined with a fluorescent bead-based multiplex immunoassay. A bi-exponential decay model was used to estimate long-term protection.

Results

In the majority of the participants, the meningococcal vaccine clearly induced naïve responses to meningococci W (MenW) and meningococci Y (MenY) as compared to a booster response to meningococci C (MenC). After 28 days, 94, 99, and 97% of the participants possessed a protective SBA titer for MenC, MenW, and MenY, respectively, which was maintained in 76, 94, and 86% 1 year post-vaccination. At this 1-year time point, significantly lower SBA titers were found in participants without a pre-vaccination SBA titer. Overall, protective antibody titers were predicted to persist after 10 years in 40–60% of the participants. The SBA titers correlated well with the meningococcal-specific IgM responses, especially for MenW and MenY. Interestingly, these IgM responses were negatively correlated with age.

Conclusion

Primary immunization with a tetravalent meningococcal vaccine was highly immunogenic in middle-aged adults, inducing protective antibody titers in the vast majority of the participants lasting for at least 1 year. The age-related decrease in highly functional IgM responses argues in favor of vaccination against de novo antigens before reaching old age and, hence, middle-aged persons are an age group of interest for future vaccine interventions to protect the aging population.

Long-term effectiveness of plasma-derived hepatitis B vaccine 22-28 years after immunization in a hepatitis B virus endemic rural area: is an adult booster dose needed?

Longan County is considered a highly endemic area for hepatitis B virus (HBV). The plasma-derived vaccine has been used in newborns in this area since 1987. A cross-sectional survey was conducted to evaluate the long-term effectiveness of this vaccine. In total, 1634 participants born during 1987-1993 and who had received a series of plasma-derived HB vaccinations at ages 0, 1, and 6 months were enrolled. Serological HBV markers were detected and compared with previous survey data. Overall the prevalence of hepatitis B surface antigen (HBsAg) in all participants was 3·79%; 3·47% of subjects who had received the first dose within 24 h were HBsAg positive, and 8·41% of subjects who had received a delayed first dose were also HBsAg positive. There were 1527 subjects identified who had received the first dose within 24 h and whose HBsAg and anti-HBc prevalence increased yearly after immunization, while the anti-HBs-positive rate and vaccine effectiveness declined. The geometric mean concentration of antibody in the anti-HB-positive participants was 55·13 mIU/ml and this declined after immunization. Fewer than 2·0% of participants had anti-HB levels ⩾1000 mIU/ml. The data show that the protective efficacy of the plasma-derived vaccinations declined and administration of HB vaccine within 24 h of birth was very important. To reduce the risk of HBV infection in this highly endemic area, a booster dose might be necessary if anti-HBs levels fall below 10 mIU/ml after age 18 years. Furthermore, studies on the immune memory induced by plasma-derived HB vaccine are needed.

Evaluation of immunization coverage in the rural area of pune, maharashtra, using the 30 cluster sampling technique

Background:

Infectious diseases are a major cause of morbidity and mortality in children. One of the most cost-effective and easy methods for child survival is immunization. Despite all the efforts put in by governmental and nongovernmental institutes for 100% immunization coverage, there are still pockets of low-coverage areas. In India, immunization services are offered free in public health facilities, but, despite rapid increases, the immunization rate remains low in some areas. The Millennium Development Goals (MDG) indicators also give importance to immunization.

Objective:

To assess the immunization coverage in the rural area of Pune.

Materials and Methods:

A cross-sectional study was conducted in the field practice area of the Rural Health Training Center (RHTC) using the WHO's 30 cluster sampling method for evaluation of immunization coverage.

Results:

A total of 1913 houses were surveyed. A total of 210 children aged 12-23 months were included in the study. It was found that 86.67% of the children were fully immunized against all the six vaccine-preventable diseases. The proportion of fully immunized children was marginally higher in males (87.61%) than in females (85.57%), and the immunization card was available with 60.95% of the subjects. The most common cause for partial immunization was that the time of immunization was inconvenient (36%).

Conclusion:

Sustained efforts are required to achieve universal coverage of immunization in the rural area of Pune district.