Antibody Levels and Infection Status of Pertussis in the Population under Pertussis Resurgence in Guangxi in 2018: A Cross-Sectional Survey.

Objective: Pertussis cases have increased markedly since 2018 in Guangxi. The aim of this study was to evaluate antibody levels and the infection status of pertussis in the resident population. Method: A total of 10,215 serum samples from residents were collected from August-November 2018 and tested for anti-pertussis IgG and toxin IgG using the enzyme-linked immunosorbent assay (ELISA). Results: Of the collected samples, 1,833 (17.94%) tested positive for anti-pertussis IgG, with the median concentration of 16.06 IU/mL. Antibody level < 10 IU/mL accounted for more than 60% in children under 4 years of age, but declined with age, whereas the percentages of the other three levels (10-40, 40-50, and ≥ 50 IU/mL) increased almost with age ( P < 0.001). Moreover, 7,924 samples were selected for anti-pertussis toxin IgG, of which 653 (8.24%) tested positive (≥ 40 IU/mL) with the median concentration of 5.89 IU/mL, and 204 participants (2.56%) had recent pertussis infection (≥ 100 IU/mL). Among the different age groups, the highest rates of positivity and recent infection were observed at 11-20 years of age, the lowest positivity rate at 5 years of age, and the lowest recent infection rate at 4 years of age ( P < 0.001, P = 0.005, respectively). Conclusion: The survey results showed that all age groups in Guangxi lacked immunity against pertussis, which was one of the main factors contributing to the resurgence of pertussis in 2018. In addition, the prevalence of pertussis is relatively high in Guangxi, and its incidence is seriously underestimated, especially in adolescents and adults.

Association of serum pertussis antibodies with acute asthma attacks in children.

Objective: The aim of this study was to examine the serum antibody levels against pertussis toxin (PT) in children experiencing an acute asthma attack and to explore the potential association between these levels and asthma. Methods: A prospective investigation was conducted, which involved 107 children with acute asthma attacks and 77 children diagnosed with bronchitis. The serum immunoglobulin G (IgG) antibody levels specific to PT were measured by using an in-house enzyme-linked immunosorbent assay. Based on the serum PT-IgG antibody levels, the children with asthma were categorized into three groups: non-pertussis infected, suspected pertussis infected, and recent pertussis infected. The clinical manifestations and pulmonary function of pediatric patients diagnosed with asthma were assessed and compared across various groups. Results: Of the total asthma group, 25 patients tested positive for PT-IgG, whereas only six patients in the bronchitis group were PT-IgG positive. The prevalence of recent pertussis infection was observed to be higher in the asthma group compared with the bronchitis group. Within the asthma group, those with recent pertussis infection exhibited a higher likelihood of experiencing wheezing and impaired lung function in comparison with the non-pertussis infection group. Conclusion: Pertussis infection is relatively common in children with asthma and correlates with the severity of asthma.

Transient reemergence of Bordetella parapertussis in France in 2022.

Between March and October 2022, a peak of detection of Bordetella parapertussis by qPCR, real-time PCR was observed in France.Hypothesis/Gap Statement. Whether this peak was due to resurgence from previous circulating lineages or reintroduction into the country was unknown.Objective. The objective of this study is to understand B. parapertussis-transient increase observed in France in 2022 whereas it had virtually stopped being reported since the start of the COVID-19 pandemic in 2020.Methods. We analysed real-time PCR (qPCR) data from the two largest French outpatient laboratories performing whooping cough diagnosis and characterized all B. parapertussis isolates collected in the 2016-2022 period by the French National Reference Centre for Whooping Cough.Results. Microbiological analyses reveal that 13 of 18 bacterial isolates collected in 2022 produce the vaccine antigen pertactin, whereas none of the 22 isolates collected in the 2016-2021 period did.Conclusion. We hypothesize a re-introduction of B. parapertussis from regions of the world where whole-cell vaccines are still in use.

Public health management of pertussis in adults: Practical challenges and future strategies.

A panel of 24 international experts met in July 2022 to discuss challenges associated with pertussis detection, monitoring, and vaccination in adults; conclusions from this meeting are presented. There has been a shift in the epidemiology of pertussis toward older children and adults. This shift has been attributed to the waning of infection- or vaccine-induced immunity, newer detection techniques causing detection bias, and possibly the replacement of whole-cell pertussis with acellular vaccines in high-income countries, which may lead to immunity waning more quickly. The burden of adult pertussis is still likely under-ascertained due to widespread under-recognition by healthcare professionals (HCPs), under-diagnosis, and under-reporting in this age group. Non-standardized testing guidance and varied case definitions have contributed to under-reporting. Key barriers to HCP engagement with the tetanus, diphtheria, and pertussis (Tdap) vaccine include low awareness, lack of time/funding, and lack of motivation due to low prioritization of Tdap.

HIV-related immune activation attenuates polyfunctional IgG and memory B-cell responses to Tdap immunization during pregnancy.

BACKGROUND: Maternal pertussis vaccination with Tdap vaccine is recommended to protect newborns from severe postnatal infection. HIV-exposed uninfected (HEU) infants have a higher incidence of pertussis infection and may particularly benefit from maternal immunization. The impact of HIV infection on the quality of IgG and memory B cell (MBC) responses to Tdap vaccination in pregnant women (PW) living with HIV (PWH) is unknown. METHODS: In this observational study, humoral immune responses to Tdap vaccination, including IgG levels, Fc-dependent effector functions, and MBC frequencies, were measured before and after vaccination in 40 PWH and 42 HIV-uninfected PW. Placental transfer of IgG and avidity were assessed in cord blood (CB). Soluble and cellular immune activation markers were quantified at baseline. FINDINGS: One month after vaccination, PWH had lower frequencies of MBC compared with HIV-uninfected PW. At delivery, PWH had attenuated pertussis-specific IgG levels and Fc-dependent effector functions. Reduced levels of maternal vaccine polyfunctional IgG and IgG avidity were transferred to HEU as compared to HIV-unexposed newborns. After adjustment with ethnicity, maternal antibody levels and gestational age at vaccination, HIV infection was independently associated with decreased levels of PT specific-IgG in CB. Both maternal and neonatal pertussis-specific IgG responses as well as PT-specific IgG avidity were inversely correlated with maternal sCD14 levels before vaccination among PWH. INTERPRETATION: Maternal HIV infection is associated with attenuated humoral immune responses to Tdap vaccination that correlate with sCD14. Suboptimal transfer of maternal immunity may further increase the risk of severe pertussis infection in HEU infants. FUNDING: This work was supported by IRIS Fund managed by the Foundation Roi Baudouin [2017J1820690206902], Association Vésale pour la Recherche Médicale and the Medical Council of CHU Saint-Pierre and has been funded in part with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, US Department of Health and Human Services, under Award No. U19AI145825. N.D. is a clinical researcher and A.M. is Research Director at the Fonds de la Recherche Scientifique (F.R.S.-FNRS), Belgium. M.E.A. was partially supported by NIHNIAID1U19AI14825. This article is published with the support of the Fondation Universitaire of Belgium.

Pertussis outbreak in neonates and young infants across Italy, January to May 2024: implications for vaccination strategies.

Since January 2024, Italy experiences a pertussis outbreak, primarily affecting neonates and unvaccinated infants at high risk of severe complications and mortality; 11 major paediatric centres noted 108 hospitalisations and three deaths by 10 May. The outbreak reflects increased circulation of Bordetella pertussis and non-adherence to immunisation recommendations during pregnancy. Public health interventions, including maternal immunisation, vaccination of infants as early as possible and post-exposure prophylaxis, are critical for reducing the burden of pertussis and preventing further mortality.

Increase of pertussis cases in the Vallès region, Catalonia, Spain, September 2023 to April 2024.

We describe a pertussis outbreak in the Vallès region of Catalonia, from September 2023 to April 2024. Incidence was high in children aged 10-14 years compared with previous outbreaks. Limited impact in newborns could be explained by the high vaccination coverage during pregnancy and at 11 months of age in 2022, at 85% and 94.1 %, respectively. A third booster vaccine dose during preadolescence should be considered and vaccination coverage in pregnant women be improved to control future outbreaks.

Predictors of maternal pertussis vaccination acceptance among pregnant women in Norway.

Maternal vaccination against pertussis is safe and provides effective protection against pertussis for the newborn, but the vaccine coverage rate remains generally low. Norway is currently planning for introduction of routine maternal pertussis vaccination. To assess maternal pertussis vaccination acceptance among pregnant Norwegian women, we surveyed women at 20-40 weeks gestation in 2019. Among the 1,148 pregnant women participating in this cross-sectional study, 73.8% reported they would accept pertussis vaccination during pregnancy if it was recommended, 6.9% would not accept and 19.2% were undecided. Predictors for low likelihood of accepting pertussis vaccination during pregnancy included low confidence in health authorities and in maternal pertussis vaccination safety and effectiveness, low awareness and adherence to influenza vaccination during pregnancy, and low awareness of pertussis vaccination. The major reasons reported for not accepting or being undecided about maternal pertussis vaccination were lack of information on vaccine safety for both mother and child. Most women reported that they would consult their general practitioner or a midwife for information if they were offered maternal pertussis vaccination. General practitioners and midwives were also regarded as the most trustworthy sources of information if the women were in doubt about accepting vaccination. We conclude that information addressing safety concerns and raising awareness about maternal pertussis vaccination could increase acceptance of maternal pertussis vaccination. Our findings highlight the pivotal role of the antenatal and primary health care services in providing such information to pregnant women.

Pertussis notifications decline in Australia during COVID-19 non-pharmaceutical interventions, 2020-2021.

Background: Following implementation of coronavirus diseases 2019 (COVID-19) non-pharmaceutical interventions (NPIs) in early 2020, declines in the incidence of other respiratory pathogens have been reported. This study aimed to assess the impact of these interventions on pertussis notifications in Australia. Methods: We compared monthly national notification rates for pertussis during the first two years of the COVID-19 pandemic (2020 and 2021) to those during the three pre-pandemic years (2017 to 2019). Incidence rate ratios (IRR) by age group and jurisdiction were calculated for 2020 and 2021 compared to the mean prepandemic annual notification rate. Results: A substantial progressive decline in pertussis notifications was seen across all age groups, with all-age notification rates more than 40% lower than the pre-pandemic period in all jurisdictions in 2020, and more than 80% lower in 2021. Notification rates decreased more slowly from a lower baseline in Victoria than in other states and territories, despite the stricter, more sustained NPIs implemented in Victoria. Conclusion: The significant decrease in pertussis notifications across all jurisdictions and age groups has likely resulted in reduced infection-acquired immunity, making maintenance of high vaccine uptake, particularly among pregnant women and young infants, of key importance.

Immunogenicity, reactogenicity, and IgE-mediated immune responses of a mixed whole-cell and acellular pertussis vaccine schedule in Australian infants: A randomised, double-blind, noninferiority trial.

BACKGROUND: In many countries, infant vaccination with acellular pertussis (aP) vaccines has replaced use of more reactogenic whole-cell pertussis (wP) vaccines. Based on immunological and epidemiological evidence, we hypothesised that substituting the first aP dose in the routine vaccination schedule with wP vaccine might protect against IgE-mediated food allergy. We aimed to compare reactogenicity, immunogenicity, and IgE-mediated responses of a mixed wP/aP primary schedule versus the standard aP-only schedule. METHODS AND FINDINGS: OPTIMUM is a Bayesian, 2-stage, double-blind, randomised trial. In stage one, infants were assigned (1:1) to either a first dose of a pentavalent wP combination vaccine (DTwP-Hib-HepB, Pentabio PT Bio Farma, Indonesia) or a hexavalent aP vaccine (DTaP-Hib-HepB-IPV, Infanrix hexa, GlaxoSmithKline, Australia) at approximately 6 weeks old. Subsequently, all infants received the hexavalent aP vaccine at 4 and 6 months old as well as an aP vaccine at 18 months old (DTaP-IPV, Infanrix-IPV, GlaxoSmithKline, Australia). Stage two is ongoing and follows the above randomisation strategy and vaccination schedule. Ahead of ascertainment of the primary clinical outcome of allergist-confirmed IgE-mediated food allergy by 12 months old, here we present the results of secondary immunogenicity, reactogenicity, tetanus toxoid IgE-mediated immune responses, and parental acceptability endpoints. Serum IgG responses to diphtheria, tetanus, and pertussis antigens were measured using a multiplex fluorescent bead-based immunoassay; total and specific IgE were measured in plasma by means of the ImmunoCAP assay (Thermo Fisher Scientific). The immunogenicity of the mixed schedule was defined as being noninferior to that of the aP-only schedule using a noninferiority margin of 2/3 on the ratio of the geometric mean concentrations (GMR) of pertussis toxin (PT)-IgG 1 month after the 6-month aP. Solicited adverse reactions were summarised by study arm and included all children who received the first dose of either wP or aP. Parental acceptance was assessed using a 5-point Likert scale. The primary analyses were based on intention-to-treat (ITT); secondary per-protocol (PP) analyses were also performed. The trial is registered with ANZCTR (ACTRN12617000065392p). Between March 7, 2018 and January 13, 2020, 150 infants were randomised (75 per arm). PT-IgG responses of the mixed schedule were noninferior to the aP-only schedule at approximately 1 month after the 6-month aP dose [GMR = 0·98, 95% credible interval (0·77 to 1·26); probability (GMR > 2/3) > 0·99; ITT analysis]. At 7 months old, the posterior median probability of quantitation for tetanus toxoid IgE was 0·22 (95% credible interval 0·12 to 0·34) in both the mixed schedule group and in the aP-only group. Despite exclusions, the results were consistent in the PP analysis. At 6 weeks old, irritability was the most common systemic solicited reaction reported in wP (65 [88%] of 74) versus aP (59 [82%] of 72) vaccinees. At the same age, severe systemic reactions were reported among 14 (19%) of 74 infants after wP and 8 (11%) of 72 infants after aP. There were 7 SAEs among 5 participants within the first 6 months of follow-up; on blinded assessment, none were deemed to be related to the study vaccines. Parental acceptance of mixed and aP-only schedules was high (71 [97%] of 73 versus 69 [96%] of 72 would agree to have the same schedule again). CONCLUSIONS: Compared to the aP-only schedule, the mixed schedule evoked noninferior PT-IgG responses, was associated with more severe reactions, but was well accepted by parents. Tetanus toxoid IgE responses did not differ across the study groups. TRIAL REGISTRATION: Trial registered at the Australian and New Zealand Clinical 207 Trial Registry (ACTRN12617000065392p).

Seroepidemiology of pertussis in Huzhou: A population-based, cross-sectional study.

PURPOSE: The resurgence of pertussis has occurred around the world. However, the epidemiological profiles of pertussis cannot be well understood by current diseases surveillance. This study was designed to understand the seroepidemiological characteristics of pertussis infection in the general population of Huzhou City, evaluate the prevalence infection of pertussis in the population, and offer insights to inform adjustments in pertussis prevention and control strategies. METHODS: From September to October 2023, a cross-sectional serosurvey was conducted in Huzhou City, involving 1015 permanent residents. Serum samples were collected from the study subjects, and pertussis toxin IgG antibodies (Anti-PT-IgG) were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). The analysis included the geometric mean concentration (GMC) of Anti-PT-IgG, rates of GMC≥40IU/mL, ≥100IU/mL, and <5IU/mL. Stratified comparisons were made based on age, vaccination history, and human categories. RESULTS: Among the 1015 surveyed individuals, the geometric mean concentration (GMC) of Anti-PT-IgG was 10.52 (95% CI: 9.96-11.11) IU/mL, with a recent infection rate of 1.58%, a serum positivity rate of 11.43%, and a proportion with <5IU/mL of 40.49%. Among 357 children with clear vaccination history, susceptibility decreased with an increasing number of vaccine doses (Z = -6.793, P < 0.001). The concentration of Anti-PT-IgG exhibited a significant post-vaccination decline over time (Z = -5.143, P < 0.001). In women of childbearing age, the GMC of Anti-PT-IgG was 7.71 (95% CI: 6.90-8.62) IU/mL, with no significant difference in susceptibility among different age groups (χ2 = 0.545, P = 0.909). The annual pertussis infection rate in individuals aged ≥3 years was 9321 (95%CI: 3336-16039) per 100,000, with peak infection rates in the 20-29, 40-49, and 5-9 age groups at 34363 (95%CI: 6327-66918) per 100,000, 22307.72 (95%CI: 1380-47442) per 100,000, and 18020(95%CI: 1093-37266) per 100,000, respectively. CONCLUSIONS: In 2023, the actual pertussis infection rate in the population of Huzhou City was relatively high. Vaccine-induced antibodies exhibit a rapid decay, and the estimated serum infection rate increases rapidly from post-school age, peaking in the 20-29 age group. It is recommended to enhance pertussis monitoring in adolescents and adults and refine vaccine immunization strategies.