School-age children and adolescents suspected of having been to be infected with pertussis in Japan

Bordetella pertussis and outer membrane vesicles

Bordetella pertussis is the causative agent of a respiratory infection called pertussis (whooping cough) that can be fatal in newborns and infants. The pathogen produces a variety of antigenic compounds which alone or simultaneously can damage various host cells. Despite the availability of pertussis vaccines and high vaccination coverage around the world, a resurgence of the disease has been observed in many countries. Reasons for the increase in pertussis cases may include increased awareness, improved diagnostic techniques, low vaccine efficacy, especially acellular vaccines, and waning immunity. Many efforts have been made to develop more effective strategies to fight against B. pertussis and one of the strategies is the use of outer membrane vesicles (OMVs) in vaccine formulations. OMVs are attracting great interest as vaccine platforms since they can carry immunogenic structures such as toxins and LPS. Many studies have been carried out with OMVs from different B. pertussis strains and they revealed promising results in the animal challenge and human preclinical model. However, the composition of OMVs differs in terms of isolation and purification methods, strains, culture, and stress conditions. Although the vesicles from B. pertussis represent an attractive pertussis vaccine candidate, further studies are needed to advance clinical research for next-generation pertussis vaccines. This review summarizes general information about pertussis, the history of vaccines against the disease, and the immune response to these vaccines, with a focus on OMVs. We discuss progress in developing an OMV-based pertussis vaccine platform and highlight successful applications as well as potential challenges and gaps.

Recent increase in pertussis incidence in South Korea: An age-period-cohort analysis

OBJECTIVES

Pertussis or whooping cough—one of the most contagious diseases—is caused by the Gram-negative bacterium Bordetella pertussis. Despite a high vaccination rate, Korea recently experienced a resurgence of pertussis. This study explores patterns and possible explanations for this resurgence through an age-period-cohort analysis.

METHODS

Using secondary data from the infectious disease portal of the Korea Disease Control and Prevention Agency and the Korea Statistical Information Service of Statistics Korea, this study analyzed the incidence of pertussis in Korea to determine which factors contributed to the recent increase using an age-period-cohort model.

RESULTS

Analysis of the age effect indicated that the age group most vulnerable to pertussis was 0-year to 2-year-olds. Analysis of the period effect showed a sharp increase in the incidence rate after 2016. Analysis of the cohort effect showed a significant decrease in incidence beginning with the 1955 birth cohort, with the risk increasing again with the 2000s birth cohort.

CONCLUSIONS

Previous studies have suggested 3 main possible explanations for our results. First, the increased incidence rate can be attributed to contact rates. Second, the rate of immunity through natural exposure has decreased due to the low number of circulating pathogens, in turn affecting the trend of infection. Lastly, variations in pathogens may have also contributed to the increase in incidence. Given that the most significant increase in incidence was observed among infants younger than 1 year old, sufficient maternal immunity must be prioritized to provide passive immunity to newborns via the placenta.

Changes and remaining challenges for the Japanese immunization program: Closing the vaccine gap

The Japanese immunization program has made considerable progress since 2009: several new vaccines have been introduced and most are included in the National Immunization Program (NIP). In October 2020, the Japanese law on immunization was revised, which resulted in a few laudable achievements. First, rotavirus vaccines were added to the NIP, 10 years after their introduction, and noteworthy studies of vaccine effectiveness and the incidence of intussusception in Japanese children were published. Second, rules on vaccine intervals-which had been a longstanding concern-were withdrawn. In addition to this revision of the law, the Japanese version of the Vaccine Information Statement (VIS) was released by the Japan Pediatric Society in 2018. The VIS provides useful caregiver information on general immunization concepts and individual vaccines. Further challenges for the Japanese immunization program include (1) administering a booster dose of pertussis-containing vaccine to preschool children or teenagers, (2) reestablishing the active recommendation for human papilloma virus vaccines, (3) adding the mumps and influenza vaccines to the NIP, and (4) ensuring optimal dosing of seasonal influenza vaccines. During the current coronavirus disease 2019 (COVID-19) pandemic, vaccination rates among children have been decreasing in many countries. In Japan, vaccination rates have been stable in infants, but declining among toddlers and school-aged children, despite public awareness of the need for timely administration of vaccines during the pandemic. Clearly, further action is needed if we are to adequately protect children living in Japan from vaccine-preventable diseases.

Seroprevalence of Bordetella pertussis among a nationally representative sample of Iranian pediatric population: The childhood and adolescence surveillance and prevention of adult noncommunicable disease-V study

Background:

Pertussis is a vaccine-preventable respiratory infection and seroepidemiology of the infection could be a marker of the pertussis immunity in a population. In many countries, despite vaccination coverage, high prevalence of pertussis has been observed. The present study aimed to evaluate the immunoglobulin G (IgG) antibody against pertussis and the role of demographic and anthropometric variables on the immunity rate in the Iranian pediatric population to evaluate the impact of existing immunization program in order to envisage future vaccination strategies to prevent infection.

Methods:

In a cross-sectional multi-centric study, 1593 samples of the students aged 7–18 years, who had been enrolled in a national survey (Childhood and Adolescence Surveillance and Prevention of Adult Noncommunicable disease-V), were randomly selected and tested for IgG antibody against Bordetella pertussis (BP) by enzyme-linked immunosorbent assay. The age, gender, education, residency, geographical region, and body mass index (BMI) were extracted from the questionnaires of the COSPIAN-Survey. Multiple logistic regression models were used to assess the associations between the variables with the IgG antibody against BP. Data were presented by odds ratio (OR), 95% confidence interval (95% CI) and P values (P): (OR [95% CI]; P).

Results:

Subjects were consisted of 774 boys and 750 girls, with a mean (standard deviation) age of 12.39 (3.03) years. Overall, BP seroprevalence was 59.8%. There were higher BMI values in seronegative ones versus seropositive (18.62 ± 4.07 vs. 18.15 ± 3.94, P = 0.041, 95% CI = 0.23 [0.02–0.92]). However, the categorized BMI for age was not significantly associated with IgG levels (0.27 [0.25–0.29]; 0.27). BP seroprevalence was not significantly different between geographical regions (0.06 [0.05–0.07]; 0.06), genders (1.17 [0.93–1.47]; 0.18), area of residence (1.07 [0.82–1.4]; 0.61), and educational levels (0.94 [0.75–1.19]; 0.62).

Conclusion:

IgG antibody against pertussis was not detected in nearly 40% of the subjects who had history of vaccination against pertussis. It is recommended to monitor the incidence of pertussis in high-risk populations closely and administer a booster dose of acellular pertussis vaccine in adolescents.

Safety of diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine in adults in Japan

Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine is generally used for booster vaccination in Europe and the United States to avoid increased reactogenicity after diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccination in infants. However, Japan has extended the use of additional DTaP vaccination without reducing the antigen dose for diphtheria and pertussis to adolescents and adults despite limited reports on its safety in adults. This prospective observational questionnaire-based study investigated the occurrence of adverse events (AEs) following DTaP vaccination between June 2018 and June 2019 in participants aged 10 years or older. Of 250 eligible participants, 235 (94%) responded regarding AEs. Of these 235 participants, 133 (56.6%) reported AEs, with 39 reporting systemic AEs (16.6%) and 120 reporting local AEs (51.1%) attributed to DTaP vaccination. The incidence of local AEs was much higher with DTaP than with non-DTaP vaccinations (51.1% vs. 10.2%), and the AEs appeared later (p<0.01) and lasted longer (p<0.01) with DTaP vaccination. However, more than 75% of these AEs resolved within 7 days. DTaP vaccination was not associated with any serious AEs. These results indicate that the DTaP vaccine can be widely used as a booster in adults as an alternative to the Tdap vaccine.

Vaccine acquired pertussis immunity was weakened at 4 years of age and asymptomatic pertussis infection was suspected based on serological surveillance

Serological surveillance of pertussis antibodies was performed in 118 children aged 1-12 years. The positivity of pertussis toxin (PT) antibodies was low at 4-6 years and significantly higher at 8-9 years, compared with those at 6 years. Fimbriae 2 (Fim2) antibody showed similar response to the PT antibody. Higher antibody titers against Fim3 were observed among subjects ≥5 years and highest at 8 years. Data demonstrated that the vaccine-induced antibodies decayed by 4-5 years and subclinical pertussis infection was suspected thereafter, suggesting the need for additional dose at around 4-5 years.