Hyperleukocytosis associated with pertussis: Two case reports

BACKGROUND

Pertussis is an acute respiratory infectious disease caused by Bordetella pertussis. Although the diphtheria-pertussis-tetanus vaccine is widely administered, there are still a number of patients with severe pertussis each year, which can lead to death, especially in infants and young children. Hyperleukocytosis is a factor related to the severity of pertussis and a risk factor for death. Reducing the leukocyte number by plasma exchange is a treatment method in clinical practice.

CASE SUMMARY

Two children with pertussis with cough as the initial symptom, developed pneumonia during the course of the illness. White blood cell counts were significantly increased with the highest values of 87.34 × 10⁹/L and 55.46 × 10⁹/L. Following anti-infection, plasma exchange, and ventilator treatment, both children recovered.

CONCLUSION

Early identification of children with pertussis complicated with hyperleukocytosis and timely plasma exchange can improve the prognosis and reduce mortality.

Risk factors and mortality in children with severe pertussis: the role of exchange transfusion in a PICU

OBJECTIVE

Although multiple risk factors have been reported for adverse outcomes in children with severe pertussis, their predictive values and the benefits of interventions such as exchange transfusion remain poorly understood. Therefore, we aimed to comprehensively evaluate the risk factors associated with mortality in children with severe pertussis and assess the potential benefits of exchange transfusion therapy.

METHODS

A retrospective analysis of 170 pertussis patients admitted to the Pediatric Intensive Care Unit (PICU) between January 2018 and June 2024 was performed.

RESULTS

Among the 170 patients, 38 (22.35%) died. The death group exhibited significantly higher white blood cell (WBC) counts (67.31 vs. 28.41 × 10^9/L, P < 0.001), neutrophils (29.95 vs. 11.61 × 10^9/L, P < 0.001), and C-reactive protein (CRP) (29 vs. 8 mg/L, P < 0.001). Additionally, sepsis (39.47% vs. 9.09%, P < 0.001), shock (63.16% vs. 6.06%, P < 0.001), ARDS (23.68% vs. 2.27%, P < 0.001), and acute kidney injury (21.05% vs. 0.76%, P < 0.001) were more prevalent in the death group. ROC analysis showed that WBC counts had a predictive value for mortality (AUC = 0.75, sensitivity = 0.78, specificity = 0.68), with an optimal cutoff of 48.58 × 10^9/L.

CONCLUSION

High WBC counts are significantly correlated with increased mortality risk in severe pertussis children, with a threshold of 48.58 × 10^9/L marking high risk. Although exchange transfusion can reduce WBC counts and improve symptoms, its benefit is limited in patients with severe secondary infections, necessitating tailored treatment strategies.

Clinical characteristics and impact of exchange transfusion in infant pertussis with extreme leukocytosis

BACKGROUND

Extreme leukocytosis in pertussis is a rare condition, and without effective interventions to reduce white blood cell counts, the mortality rate can approach 100%. The clinical characteristics of these patients and the application of exchange transfusion (ET) in their management are not yet clear.

METHODS

This retrospective study examines the clinical characteristics and impact of ET in infant pertussis with extreme leukocytosis.

RESULTS

We have included six infant pertussis patients with extreme leukocytosis, all of whom were female and underwent ET. Two patients survived, while four died. The surviving patients were relatively older at disease onset compared to those who died, and all three unvaccinated patients died. All patients required admission to the pediatric intensive care unit, presenting with fever, whooping cough, cyanosis, severe pneumonia, and respiratory failure. Pulmonary consolidation, cardiovascular failure, and pulmonary hypertension (PH) were also common, especially among those who died. Hypoglycemia and seizures were rare. Acute-phase proteins, such as C-reactive protein and procalcitonin, were elevated to varying degrees. ET effectively reduced peripheral blood leukocytes; however, a significant increase in leukocytes was observed 1-2 days after the first ET in the deceased patients.

CONCLUSION

Extreme hyperleukocytosis is more commonly observed in young female children with pertussis. Younger age, unvaccinated status, and the presence of concurrent heart failure and PH may be associated with a poor prognosis. ET can effectively reduce peripheral blood leukocytes, but a rapid leukocyte rebound post-ET may be indicative of impending death.

Effect of Early Administration of Clarithromycin or Azithromycin on Symptoms of Pertussis in Infants

Background: A resurgence of pertussis has been observed in several geographic areas in the post-COVID-19 era. Macrolides are the first-choice antibiotics for the treatment of pertussis. Limited data exist on the impact of the early administration of clarithromycin or azithromycin on infants' pertussis symptoms. Methods: This retrospective cohort study analyzed infants enrolled in an enhanced surveillance program for pertussis at a single Italian clinical reference center between 2015 and 2020. All cases were laboratory-confirmed. This study compared outcomes based on the timing of macrolide antibiotic treatment: early administration (within 7 days of cough onset) versus late administration (8 days or later). Key outcomes included cough duration, symptom frequency, and complication rates. Results: We studied 148 infants with confirmed pertussis. The median duration of coughing was 14 days in infants with early administration and 24 days in those with late administration. The occurrence of symptoms differed for apnea (62.6% for early administration; 84.6% for late administration). In a multivariable Cox model, the duration of the cough was lower in infants receiving antibiotics within 7 days from the beginning of the cough compared with those starting later (HR = 0.36, 95% CI: 0.25-0.53, p < 0.001). Clarithromycin was associated with a shorter duration of coughing (HR = 0.42, 95% CI: 0.19-0.92, p = 0.030) independently from other factors. Regarding the occurrence of symptoms, children receiving antibiotics later were three times more likely to experience apnea compared to those treated early (p = 0.008). Conclusions: Early treatment with clarithromycin or azithromycin for infants with pertussis improves clinical symptoms. Clarithromycin may be more effective than azithromycin in shortening coughing. The early administration of antibiotics may also help prevent the spread of disease during the resurgence of pertussis and should be considered regardless of the laboratory confirmation, while taking into account the potential side effects of an unnecessary therapy.

Pertussis in Early Infancy: Diagnostic Challenges, Disease Burden, and Public Health Implications Amidst the 2024 Resurgence, with Emphasis on Maternal Vaccination Strategies

Bordetella pertussis is the causative agent of pertussis or whooping cough, an acute and highly contagious respiratory infection that can have serious and fatal complications such as pneumonia, encephalopathy, and seizures, especially for newborns. The disease is endemic not only in the European Union (EU)/European Economic Area (EEA) but also globally. Larger outbreaks are anticipated every three to five years, even in countries where vaccination rates are high. Despite the high pertussis vaccination coverage in developed countries and a low rate of pertussis incidence for many years, especially during the COVID-19 pandemic, the incidence of pertussis has been on the rise again, with outbreaks in some places, which is referred to as "re-emergence of pertussis". The aim of this review is to underscore the critical importance of achieving high vaccination coverage, particularly among pregnant women, to safeguard vulnerable neonates from pertussis during their early months, before they are eligible for vaccination. This aligns with the need to address diagnostic challenges, mitigate disease severity, and strengthen public health strategies in light of the ongoing 2024 Bordetella pertussis resurgence.

Pertussis in the Post-COVID-19 Era: Resurgence, Diagnosis, and Management

Pertussis is endemic worldwide, with epidemics occurring every 2 to 5 years despite a high vaccination coverage. After limited circulation during the coronavirus disease 2019 (COVID-19) pandemic, pertussis cases have increased rapidly worldwide since mid-late 2023, returning to pre-pandemic patterns. In Korea, 90 cases of pertussis were reported from April 2020 to May 2023, with elderly individuals aged ≥65 years accounting for 48.9%. Pertussis cases have increased sharply since June 2024, showing a nationwide epidemic, with a large increase among adolescents aged 13-15 years. As of August 2024, the national incidence rate of pertussis was estimated to be 37.75 per 100,000 population, with the highest incidence of 526.2 per 100,000 population in 13-year-olds. In Europe, during 2023-2024, an increase in pertussis incidence among infants was observed, along with large increases in 10-19-year-olds. In China, the number of reported cases of pertussis has increased rapidly since late 2023, with an age shift to older children, increase of vaccine escape, and a marked increase in the prevalence of macrolide-resistant Bordetella pertussis. The recent global resurgence of pertussis is due to decreased opportunities for boosting immunity by natural infection during the COVID-19 pandemic in combination with waning of immunity-induced pertussis vaccines.

Interferon lambda signaling in neutrophils enhances the pathogenesis of Bordetella pertussis infection

Interferon lambda plays diverse roles in bacterial infections. Previously, we showed that interferon lambda is induced in the lungs of Bordetella pertussis-infected adult mice and exacerbates inflammation. Here, we report that mice lacking the interferon lambda receptor 1 specifically on neutrophils (MRP8creIFNLR1fl/fl mice) exhibit reduced lung bacterial load and inflammation compared to wild-type mice during B. pertussis infection. In B. pertussis-infected wild-type mice, lung type I and III IFN responses were higher than in MRP8creIFNLR1fl/fl mice, correlating with increased lung inflammatory pathology. There was an increased proportion of interferon gamma-producing neutrophils in the lungs of MRP8creIFNLR1fl/fl mice compared to wild-type mice. IFNLR1-/- neutrophils incubated with B. pertussis exhibited higher killing compared to wild-type neutrophils. Treatment of wild-type neutrophils with interferon lambda further decreased their bacterial killing capacity and treatment of wild-type mice with interferon lambda increased lung bacterial loads. Contributing to the differential killing, we found that IFNLR1-/- neutrophils exhibit higher levels of reactive oxygen species, myeloperoxidase, matrix metalloproteinase-9 activity, neutrophil extracellular traps, and interferon gamma secretion than wild-type neutrophils, and inhibiting NADPH oxidase inhibited bacterial killing in IFNLR1-/- neutrophils. B. pertussis-induced interferon lambda secretion and IFNLR1 gene expression in mouse and human neutrophils and this was dependent on the bacterial virulence protein pertussis toxin. Pertussis toxin enhanced bacterial loads in wild type but not in MRP8creIFNLR1fl/fl or IFNLR1-/- mice. Thus, pertussis toxin disrupts neutrophil function by enhancing type III IFN signaling, which prevents neutrophils from effectively clearing B. pertussis during infection, leading to higher bacterial loads and exacerbation of lung inflammation.

Pertussis infection in critically ill infants: meta-analysis and validation of a mortality score

BACKGROUND

Despite widespread vaccination programs, pertussis continues circulating within populations and remains a life-threatening infection in infants. While several mortality risk factors have been described, a comprehensive synthesis is lacking. We conducted a meta-analysis of studies investigating mortality risk factors in Pertussis infections and validated those factors in a large cohort.

METHODS

Observational studies published in English were systematically searched in PubMed, EMBASE, and LiSSa databases from 01/2000 to 06/2024. The search yielded 816 unique citations. The primary outcome was mortality before discharge from the Pediatric Intensive Care Unit (PICU). Two independent reviewers assessed the risk of bias and extracted data. A REML-random effect model was used to calculate pooled prevalence and conduct the analysis. The identified risk factors were subsequently evaluated in a monocentric cohort of patients admitted to a tertiary hospital's PICU for severe pertussis between January 1996 and December 2020. Data analysis was conducted between June and August 2024.

RESULTS

Seventeen studies, including 2,725 patients, met the inclusion criteria. The pooled prevalence of mechanical ventilation, continuous renal replacement therapy, and Extracorporeal Membrane Oxygenation support were 55% (95% CI: 40-70; I2 = 98), 15% (95% CI: 3-27; I2 = 95), and 8% (95% CI: 3-12; I2 = 93), respectively. The pooled mortality incidence was 19% (95% CI:12-26; I2 = 96). Identified mortality risk factors included elevated heart rate, presence of pulmonary hypertension, presence of seizures, and elevated white blood cell (WBC) count. Validation in an 83-patient cohort (median age: 45 days, IQR: 30-55) revealed a mortality rate of 12%. Risk factors identified in the meta-analysis were significantly associated with non-survival in the cohort. A mortality prediction score was developed incorporating age < 30 days, heart rate > 200/min, and WBC > 30 G/l, achieving an area under the curve of 0.92 (95% CI: 0.86-0.99).

CONCLUSION

This meta-analysis identified a simple yet effective score to assess the severity of pertussis infection in infants admitted to PICU. Accurate risk stratification may enable timely treatment of critically ill patients, potentially improving outcomes.

TRIAL REGISTRATION

The study protocol was registered on PROSPERO: CRD42024582057.

Pertussis Vaccination During Pregnancy: Regional Situation and Impact of Implementation on National Immunization Programs in Latin America

BACKGROUND

Infants face a high risk of morbidity and mortality from pertussis early in life, leading to the adoption of maternal vaccination. This study aimed to review the characteristics of the maternal pertussis vaccination in Latin American (LATAM) countries and evaluate their impact on pertussis absolute mortality and case fatality rate (CFR) in infants under 1 year old.

METHODS

LATAM countries with maternal tetanus, diphtheria and acellular pertussis (Tdap) vaccination in their National Immunization Programs were included. Data on pertussis incidence, deaths and cases in <1-year-old; characteristics of Tdap vaccination in pregnancy; and third dose of diphtheria, tetanus and pertussis and Tdap coverage rates were collected and analyzed. The impact on absolute mortality and CFR was assessed by comparing the percentage reduction between 4 years before and after (up to 2019) the Tdap introduction for each country.

RESULTS

The LATAM countries included were Argentina, Brazil, Chile, Costa Rica, Colombia, El Salvador, Mexico, Panamá, Paraguay, Peru and Uruguay. Post-Tdap introduction, pertussis incidence declined notably, especially from 2020. The beginning of the maternal Tdap strategy varied, occurring between 2012 and 2019, with a common recommendation at 20 weeks gestation. In most countries, absolute mortality and CFR decreased, though variations ranged from -9.9% to 88.9% and -60.6% to 81.2%, respectively. Tdap and third dose of diphtheria, tetanus and pertussis coverage rates declined by 2021, with rates ranging from 37% to 92% and 58% to 95%, respectively.

CONCLUSION

The characteristics of maternal Tdap vaccination varied across LATAM countries. The vaccine implementation into the National Immunization Program has reduced pertussis cases, deaths and CFR in infants <1-year-old in most countries.

Hydroxyurea for Malignant Pertussis in Critically Ill Children

OBJECTIVES

Malignant pertussis, the most severe manifestation of Bordetella pertussis infection, is characterized by multiple organ failure and a high mortality rate despite advanced intensive care measures. Hyperleukocytosis is the hallmark of malignant pertussis and necessitates urgent and aggressive interventions. Among the therapeutic options, leukoreduction via whole blood exchange (BE) transfusion has been associated with significant procedural risks and potential clinical deterioration. Hydroxyurea was recently proposed as a pharmacological alternative for leukoreduction. This study reports our clinical experience with hydroxyurea as an alternative to BE in managing infants with malignant pertussis admitted to a PICU.

DESIGN

Prospective case series.

SETTING

A referral PICU in France.

PATIENTS

Critically ill infants (n = 27) with severe pertussis infection.

INTERVENTIONS

Hydroxyurea therapy or BE transfusion.

MEASUREMENTS AND MAIN RESULTS

We reviewed all critically ill infants admitted to our unit for severe pertussis between January 2017 and July 2024. The primary outcome was 28-day survival, and the secondary outcome was the efficacy of hydroxyurea on blood leukocyte count reduction. Among the 27 infants admitted for severe pertussis, 12 exhibited features of malignant pertussis. Of these, seven were treated with hydroxyurea and five with BE. The majority of infants were term and under 3 months old. All patients required ventilatory support, with eight on invasive mechanical ventilation and three receiving extracorporeal membrane oxygenation therapy. Overall mortality was three of 12 (25%). Hydroxyurea was administered at a dose of 20 mg/kg/d for a median duration of 12 days. Hyperleukocytosis was successfully reduced within 7 days.

CONCLUSIONS

Hydroxyurea is an alternative therapy for malignant pertussis infection that can efficiently address hyperleukocytosis with limited mortality.

Association between pertactin-producing Bordetella pertussis and fulminant pertussis in infants: a multicentre study in France, 2008-2019

OBJECTIVES

Virulence factors of the causative agent, Bordetella pertussis, may be involved in fulminant pertussis, the most severe form of whooping cough (pertussis) in infants. We aimed to assess the association between fulminant pertussis and the status of pertactin (PRN) production of B. pertussis clinical isolates.

METHODS

Symptomatic infants aged <6 months with a positive B. pertussis culture from 2008-2019 were included. B. pertussis isolates and clinical data were collected from French hospital laboratories through the national pertussis surveillance network. Fulminant pertussis was defined as a case with a leukocyte count >40 × 109/L and at least one of the following criteria: respiratory failure, pulmonary hypertension, shock, or multiple organ failure. PRN production was assessed by western blotting. Baseline characteristics of infants and microbiological findings were compared between patients with and without fulminant pertussis. To identify patient and microbiological features associated with fulminant pertussis, a multivariable modified Poisson regression model was developed with confounders selected using a directed acyclic graph.

RESULTS

We included 361 infants with pertussis (median age 63 days [interquartile range, 39-86]), of whom 32 (9%) progressed to fulminant pertussis. None of the mothers was vaccinated during pregnancy. Of the 361 implicated B. pertussis isolates, 294 (81%) produced PRN. Patients with fulminant pertussis were more often neonates (adjusted relative risk [aRR]: 3.62, 95% confidence interval [CI]: 1.76-7.44), infants with a history of prematurity (aRR: 7.08, 95% CI: 3.06-16.36), unvaccinated infants (aRR: 4.42, 95% CI: 1.02-19.24), and infants infected by PRN-producing isolates (aRR: 3.76, 95% CI: 1.02-13.83).

DISCUSSION

PRN-producing B. pertussis was independently associated with an increased risk of fulminant pertussis. In a context where PRN-containing acellular pertussis vaccines favour the emergence of PRN-deficient isolates, our study suggests a positive role for such vaccines in driving the evolution of B. pertussis populations towards reduced virulence.

Severe pertussis infections in pediatric intensive care units: a multicenter study

This study aims to evaluate the clinical course of critical pertussis illness to the pediatric intensive care unit in Istanbul. The study was conducted as a multicenter, retrospective study between January 1, 2023, and December 31, 2023. Cases with positive polymerase chain reaction testing for Bordetella pertussis of nasopharyngeal swab samples within the first 24 h of pediatric intensive care unit admission were recorded. We divided the patients into exchange blood transfusion group and non-exchange blood transfusion group, comparing related factors and clinical characteristics among each group. A total of 50 children with severe pertussis were enrolled in the study, including 29 males (58%), with a median age of 9.14 weeks (range, 7.29-15.3 weeks). The mortality rate for severe pertussis was 8%. Exchange blood transfusion was performed in eight patients (16%). There were no significant differences between patients who received exchange blood transfusion and those who did not in terms of age, male gender, gestational age, birth weight, comorbidities, presenting symptoms, duration of cough, prior antibiotic use, vaccination status, coinfections, PICU length of stay, or mortality (p > 0.05). Children who underwent exchange blood transfusion had significantly higher white blood cell (WBC) counts, lymphocyte counts, neutrophil counts, and C-reactive protein (CRP) levels compared to those who did not receive the procedure (p < 0.05). Pulmonary hypertension was observed in 50% of the children who received exchange blood transfusion, while it was present in only 11.8% of those who did not undergo the procedure (p < 0.05). Additionally, patients who received exchange blood transfusion had higher incidences of respiratory failure, cardiac failure or arrest, inotrope requirement, and mechanical ventilation compared to those who did not receive the transfusion (p < 0.05).

CONCLUSIONS

Pertussis can lead to severe complications and mortality in critically ill infants. Most severe pertussis occurred in young, unimmunized infants. Children admitted with pertussis with high CRP level, high WBC and lymphocyte, and cardiac and respiratory failure can need exchange blood transfusion.

WHAT IS KNOWN

• Pertussis is a highly contagious respiratory infection caused by Bordetella pertussis, which primarily affects infants. Despite vaccination efforts, pertussis remains a significant cause of morbidity and mortality in infants, particularly those too young to be fully vaccinated.

WHAT IS NEW

• In pertussis, exchange blood transfusion may be considered in cases of severe pulmonary hypertension or cardiogenic shock, as indicated by echocardiographic findings, in conjunction with leukocytosis observed on laboratory tests.

Pertussis clinical profile shift, severity, prediction in a tertiary hospital: A comparative study before, during, and after COVID-19 in Southern China

OBJECTIVE

To analyze the epidemiological characteristics, clinical manifestations, antimicrobial resistance and develop a predictive model for severe pertussis spanning five years - before, during, and after the COVID-19 pandemic - in Shenzhen children's hospital in southern China, aiming to provide insights into the pandemic impact and control measures on the pertussis disease profile.

METHODS

Demographic, clinical, vaccination, and laboratory data were collected for patients who tested positive for pertussis by polymerase chain reaction and/or culture from January 1, 2019, to March 30, 2024. Analysis included changes in demographic and clinical features, indicators of severe cases, and resistance patterns over the study period.

RESULTS

During this period, 3963 patients were diagnosed, with 79 severe (PICU admitted) cases; 1433 isolates underwent antimicrobial susceptibility testing. In late 2023, pertussis cases began to increase. From 2019 to 2024, the proportion of cases among 4-6 year olds rose from 4.9 % to 28.6 %, and among 7-11 year olds from 0.7 % to 21.2 %. Macrolide resistance surged from 46.5 % in 2019 to 97.3 % in 2024, with 80 % of resistant hospitalized cases initially treated with macrolides. Clinical severity and co-infection increased post-pandemic, with a larger number of cases necessitating antibiotic changes and enhanced supportive care. Vaccination protected against severe disease. Indicators such as white blood cell count, lymphocyte to neutrophil ratio, platelet count, cyanosis and pneumonia predicted disease severity.

CONCLUSIONS

Post-pandemic, pertussis cases shifted from infants to school-aged children, with increased clinical severity and high macrolide resistance. Urgent measures are needed to optimize vaccination schedules and develop management strategies addressing and changing epidemiological patterns.

Expert consensus for pertussis in children: new concepts in diagnosis and treatment

BACKGROUND

Pertussis resurgence has been reported worldwide in the past two decades. Pertussis is still endemic and difficult to control though with universal vaccination in children. The resurgence may be related to multiple variables, such as increased disease awareness and laboratory tests, waning of immunity following vaccination, and/or genetic mutations of Bordetella pertussis. For better pertussis prevention, diagnosis, and management, we called up an expert panel to develop this expert consensus to provide new concepts in diagnosis and treatment for clinical practice.

DATA SOURCES

The expert groups collected clinical evidence, summarized their clinical experiences, evaluated preliminary recommendations or guidelines, and then organized open-ended discussions to form the recommendations. This consensus was developed by reviewing the literature and studies in databases, including PubMed, Cochrane, EMBASE, the China Biomedical Database, and the Chinese Journal Full-text Database up to May 2024. The search terms included "pertussis" or "whooping cough", "children", "diagnosis", and "treatment".

RESULTS

The burden of pertussis has also changed from infants to  school children and adults, and these age groups have consequently become the main source of infection for vulnerable population including infants and newborns. In China, a high prevalence of erythromycin-resistant Bordetella pertussis (ERBP) has been reported in the past decade. ERBP may lead to failed clinical empirical treatment with macrolides, which poses a great challenge for pertussis management and control. For better management of pertussis, a flow diagram for diagnosis and treatment of pertussis was presented in this consensus. This consensus also described the diagnostic criteria for pertussis, high-risk cases, and severe pertussis. Macrolides can still be used to treat confirmed erythromycin-sensitive B. pertussis (ESBP) infections, whereas oral trimethoprim-sulfamethoxazole therapy is the initial treatment option for children older than two months. For infants younger than two months, severe patients, or those exhibiting a high degree of sulfonamide allergy, intravenous administration of piperacillin or cefoperazone-sulbactam is advised.

CONCLUSIONS

This expert consensus provides a comprehensive guidance and a reference for the diagnosis and treatment of pertussis in children.

Alpha-1 antitrypsin inhibits pertussis toxin

Pertussis (whooping cough) is a vaccine-preventable but re-emerging, highly infectious respiratory disease caused by Bordetella pertussis. There are currently no effective treatments for pertussis, complicating care for nonvaccinated individuals, especially newborns. Disease manifestations are predominantly caused by pertussis toxin (PT), a pivotal virulence factor classified as an ADP-ribosylating AB-type protein toxin. In this work, an unbiased approach using peptide libraries, bioassay-guided fractionation and mass spectrometry revealed α1-antitrypsin (α1AT) as a potent PT inhibitor. Biochemistry-, cell culture-, and molecular modeling-based in vitro experimentation demonstrated that the α1AT mode of action is based on blocking PT-binding to the host target cell surface. In the infant mouse model of severe pertussis, α1AT expression was reduced upon infection. Further, systemic administration of α1AT significantly reduced B. pertussis-induced leukocytosis, which is a hallmark of infant infection and major risk factor for fatal pertussis. Taken together our data demonstrates that α1AT is a novel PT inhibitor and that further evaluation and development of α1AT as a therapeutic agent for pertussis is warranted. Importantly, purified α1AT is already in use clinically as an intravenous augmentation therapy for those with genetic α1AT deficiency and could be repurposed to clinical management of pertussis.

International treatment outcomes of neonates on extracorporeal membrane oxygenation (ECMO) with persistent pulmonary hypertension of the newborn (PPHN): a systematic review

BACKGROUND

PPHN is a common cause of neonatal respiratory failure and is still a serious condition and associated with high mortality.

OBJECTIVES

To compare the demographic variables, clinical characteristics, and treatment outcomes in neonates with PHHN who underwent ECMO and survived compared to neonates with PHHN who underwent ECMO and died.

METHODS

We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline and searched ProQuest, Medline, Embase, PubMed, CINAHL, Wiley online library, Scopus and Nature for studies on the development of PPHN in neonates who underwent ECMO, published from January 1, 2010 to May 31, 2023, with English language restriction.

RESULTS

Of the 5689 papers that were identified, 134 articles were included in the systematic review. Studies involving 1814 neonates with PPHN who were placed on ECMO were analyzed (1218 survived and 594 died). Neonates in the PPHN group who died had lower proportion of normal spontaneous vaginal delivery (6.4% vs 1.8%; p value > 0.05) and lower Apgar scores at 1 min and 5 min [i.e., low Apgar score: 1.5% vs 0.5%, moderately abnormal Apgar score: 10.3% vs 1.2% and reassuring Apgar score: 4% vs 2.3%; p value = 0.039] compared to those who survived. Neonates who had PPHN and died had higher proportion of medical comorbidities such as omphalocele (0.7% vs 4.7%), systemic hypotension (1% vs 2.5%), infection with Herpes simplex virus (0.4% vs 2.2%) or Bordetella pertussis (0.7% vs 2%); p = 0.042. Neonates with PPHN in the death group were more likely to present due to congenital diaphragmatic hernia (25.5% vs 47.3%), neonatal respiratory distress syndrome (4.2% vs 13.5%), meconium aspiration syndrome (8% vs 12.1%), pneumonia (1.6% vs 8.4%), sepsis (1.5% vs 8.2%) and alveolar capillary dysplasia with misalignment of pulmonary veins (0.1% vs 4.4%); p = 0.019. Neonates with PPHN who died needed a longer median time of mechanical ventilation (15 days, IQR 10 to 27 vs. 10 days, IQR 7 to 28; p = 0.024) and ECMO use (9.2 days, IQR 3.9 to 13.5 vs. 6 days, IQR 3 to 12.5; p = 0.033), and a shorter median duration of hospital stay (23 days, IQR 12.5 to 46 vs. 58.5 days, IQR 28.2 to 60.7; p = 0.000) compared to the neonates with PPHN who survived. ECMO-related complications such as chylothorax (1% vs 2.7%), intracranial bleeding (1.2% vs 1.7%) and catheter-related infections (0% vs 0.3%) were more frequent in the group of neonates with PPHN who died (p = 0.031).

CONCLUSION

ECMO in the neonates with PPHN who failed supportive cardiorespiratory care and conventional therapies has been successfully utilized with a neonatal survival rate of 67.1%. Mortality in neonates with PPHN who underwent ECMO was highest in cases born via the caesarean delivery mode or neonates who had lower Apgar scores at birth. Fatality rate in neonates with PPHN who underwent ECMO was the highest in patients with higher rate of specific medical comorbidities (omphalocele, systemic hypotension and infection with Herpes simplex virus or Bordetella pertussis) or cases who had PPHN due to higher rate of specific etiologies (congenital diaphragmatic hernia, neonatal respiratory distress syndrome and meconium aspiration syndrome). Neonates with PPHN who died may need a longer time of mechanical ventilation and ECMO use and a shorter duration of hospital stay; and may experience higher frequency of ECMO-related complications (chylothorax, intracranial bleeding and catheter-related infections) in comparison with the neonates with PPHN who survived.

Vaccination coverage during pregnancy and factors associated with refusal of recommended vaccinations: An Italian cross sectional study

Background

The vaccines recommended during pregnancy are the Tdap, the influenza vaccine, and, during the SARS-CoV-2 pandemic, the vaccine against COVID-19. This survey aimed at determining vaccination coverage among pregnant women and adverse events, reasons for vaccine refusal, and factors associated with vaccine uptake.

Methods

A single-center cross-sectional study was conducted on women who delivered between March and April 2022 at Careggi University Hospital in Florence, Italy. Information on the vaccinations (Tdap, influenza and COVID-19) received during pregnancy were collected through in-person interviews.

Results

Among 307 enrolled women (response rate 99 % on a study population of 310 eligible women), 74 % of patients were vaccinated with Tdap, 82 % against COVID-19, and only 33 % against influenza. Vaccination coverage for Tdap and COVID-19 was significantly higher among Italian than foreign patients (80 % vs 51 %, p < 0.001 and 86 % vs 69 %, p = 0.002, respectively), and for Tdap was higher among patients followed in the private vs public care setting. The main reasons behind refusal of vaccinations were low risk perception of influenza (41 %), insufficient information received from the prenatal care provider regarding the Tdap (35 %), and, for the COVID-19, fear of vaccine side effects (64 %), and concerns about effects on the fetus (70 %).

Conclusions

Adherence to the influenza vaccine was low because of reduced perception of the disease risks. The difference in vaccination coverage between Italians and foreigners is an example of healthcare disparity. Better information provided to patients about vaccines' efficacy and safety is advisable to increase acceptance of recommended vaccines.

Age-dependent natural killer cell and interferon γ deficits contribute to severe pertussis in infant mice

Many respiratory infections are selectively injurious to infants, yet the etiology of age-associated susceptibility is unknown. One such bacterial pathogen is Bordetella pertussis. In adult mice, innate interferon γ (IFN-γ) is produced by natural killer (NK) cells and restricts infection to the respiratory tract. In contrast, infant pertussis resembles disease in NK cell- and IFN-γ-deficient adult mice that experience disseminated lethal infection. We hypothesized that infants exhibit age-associated deficits in NK cell frequency, maturation, and responsiveness to B. pertussis, associated with low IFN-γ levels. To delineate mechanisms behind age-dependent susceptibility, we compared infant and adult mouse models of infection. Infection in infant mice resulted in impaired upregulation of IFN-γ and substantial bacterial dissemination. B. pertussis-infected infant mice displayed fewer pulmonary NK cells than adult mice. Furthermore, the NK cells in the infant mouse lungs had an immature phenotype, and the infant lung showed no upregulation of the IFN-γ-inducing cytokine IL-12p70. Adoptive transfer of adult NK cells into infants, or treatment with exogenous IFN-γ, significantly reduced bacterial dissemination. These data indicate that the lack of NK cell-produced IFN-γ significantly contributes to infant fulminant pertussis and could be the basis for other pathogen-induced, age-dependent respiratory diseases.

Antibody and B-cell Immune Responses Against Bordetella Pertussis Following Infection and Immunization

Neither immunization nor recovery from natural infection provides life-long protection against Bordetella pertussis. Replacement of a whole-cell pertussis (wP) vaccine with an acellular pertussis (aP) vaccine, mutations in B. pertussis strains, and better diagnostic techniques, contribute to resurgence of number of cases especially in young infants. Development of new immunization strategies relies on a comprehensive understanding of immune system responses to infection and immunization and how triggering these immune components would ensure protective immunity. In this review, we assess how B cells, and their secretory products, antibodies, respond to B. pertussis infection, current and novel vaccines and highlight similarities and differences in these responses. We first focus on antibody-mediated immunity. We discuss antibody (sub)classes, elaborate on antibody avidity, ability to neutralize pertussis toxin, and summarize different effector functions, i.e. ability to activate complement, promote phagocytosis and activate NK cells. We then discuss challenges and opportunities in studying B-cell immunity. We highlight shared and unique aspects of B-cell and plasma cell responses to infection and immunization, and discuss how responses to novel immunization strategies better resemble those triggered by a natural infection (i.e., by triggering responses in mucosa and production of IgA). With this comprehensive review, we aim to shed some new light on the role of B cells and antibodies in the pertussis immunity to guide new vaccine development.

Risk Factors of Exchange Blood Transfusion in Infants With Severe Pertussis

Exchange blood transfusion (ET) reportedly improves the outcomes of the patients with severe pertussis accompanied with deadly complications continued to worsen despite intensive therapeutic measures. This study assessed the medical records of 12 patients with severe pertussis requiring ET therapy who were admitted to our medical center. Of the 12 patients requiring ET therapy, 8 survived and 4 died. The independent risk factors for requiring ET therapy in infants with severe pertussis were T ≥ 38.5°C (odds ratio [OR], 11.697; 95% confidence interval [CI], 1.325-262.184; P = .046), C-reactive protein (CRP) >30 mg/L (OR, 62.393; 95% CI, 6.264-2381.773; P = .004), and WBC > 40.0 × 109/L (OR, 68.509; 95% CI, 8.118-1829.695; P = .001). ET therapy worked effectively for our severe pertussis cases. When the severe pertussis patients with T ≥ 38.5°C, CRP >30 mg/L, and WBC > 40.0 × 109/L, ET therapy might be taken into consideration.

Metagenomics next-generation sequencing assists in the diagnosis of infant pertussis encephalopathy: A case report

RATIONALE

Pertussis is an acute respiratory infection that often occurs in the pediatric population, especially in infants under 3 months old. Bordetella pertussis is the causative agent of pertussis, which can lead to pneumonia, encephalopathy, and pulmonary hypertension, causing death in severe cases. Therefore, an accurate and comprehensive diagnosis of the pathogen is essential for effective treatment.

PATIENT CONCERNS

We report a case of 2-month-old male infant admitted to the pediatric intensive care unit of West China Second University due to hoarse cough for 7 days, accompanied by a crowing-like echo, fever and listlessness, occasional nonprojectile vomiting with anorexia, shortness of breath, accelerated heart rate, cyanosis of the lips, and convulsions. B pertussis was identified by metagenomic next-generation sequencing in blood and cerebrospinal fluid and polymerase chain reaction assay using blood.

DIAGNOSES

The infant was diagnosed with pertussis.

INTERVENTIONS

Intravenous infusion of erythromycin (50 mg/kg/d) for anti-infection and dexamethasone for alleviating intracranial inflammatory reaction were given.

OUTCOMES

The patient was eventually recovered and discharged.

LESSONS

This case report emphasized the importance of metagenomic next-generation sequencing using cerebrospinal fluid and blood for early diagnosis of pertussis-associated encephalopathy.

Vaccination in Pregnancy against Pertussis: A Consensus Statement on Behalf of the Global Pertussis Initiative

Infants are at high risk for severe morbidity and mortality from pertussis disease during early infancy. Vaccination against pertussis in pregnancy has emerged as the ideal strategy to protect infants during these early, vulnerable, first months of life. On 30 November and 1 December 2021, the Global Pertussis Initiative held a meeting that aimed to discuss and review the most up-to-date scientific literature supporting vaccination against pertussis in pregnancy and outstanding scientific questions. Herein, we review the current and historically published literature and summarize the findings as consensus statements on vaccination against pertussis in pregnancy on behalf of the Global Pertussis Initiative.

Severe Pertussis Infection With Hyperleukocytosis in a 10-Month-Old Unvaccinated Amish Female: A Case Report

Bordetellapertussis (B. pertussis) commonly infects individuals of all ages. However, pertussis, the disease caused by B. pertussis infection, is most severe in young infants. Severe pertussis, defined by the presence of refractory hypoxemia, pneumonia, cardiogenic shock, and hyperleukocytosis, is associated with significant morbidity and mortality. Both hyperleukocytosis and pulmonary hypertension have been found to be predictive of mortality in young infants. Leukoreductive strategies such as leukapheresis and exchange transfusion have been employed to treat these complications. Pulmonary hypertension is thought to be a result of aggregation of white blood cells in pulmonary vasculature; however, studies have suggested that the mechanism of pulmonary hypertension is multifactorial. We report a case of a 10-month-old unvaccinated Amish female with pertussis complicated by an initial hyperleukocytosis of 204,900 10³/uL successfully treated with leukapheresis in our pediatric intensive care unit. This infant never showed signs of pulmonary hypertension, which is often associated with hyperleukocytosis in severe or fatal cases of pertussis in infants and neonates. To our knowledge, this is the most significant degree of hyperleukocytosis reported in pertussis. The findings in this case support the clinical utility of leukoreductive therapy in severe pertussis and provide some evidence that the mechanism of pulmonary hypertension in these patients is multifactorial.

Severe pertussis disease in a paediatric population: The role of age, vaccination status and prematurity

AIM

To estimate hospitalisation rate and investigate the role of age, prematurity and vaccination status in severe pertussis cases.

METHODS

We retrospectively evaluated 200 children aged 0-14 years, admitted to the emergency rooms of Meyer Hospital of Florence and Pisa Hospital with a diagnosis of pertussis from 1 October 2010 to 31 January 2020.

RESULTS

Children younger than 12 months were 63.0%. Preterm infants were 6.5%. The rate of hospitalisation was 49.0%. Among hospitalised cases, 80.6% were younger than 5 months. Overall, 62.0% were unvaccinated; this percentage increased among hospitalised (73.5%) and preterm subsamples (76.9%). Delays in pertussis vaccination were found in 57.7% of term infants and in 80.0% of preterms. Multivariable analysis confirmed the age under 2 months as the variable at higher risk for hospitalisation (OR 4.49, 95% CI 1.85-10.96, p < 0.001). Being fully vaccinated represented a significant protective factor (OR 0.12, 95% CI 0.04-0.35, p < 0.001).

CONCLUSION

Older classes of age and a complete vaccination, in time with the recommended schedule, are both protective factors for hospitalisation in severe pertussis disease. The widespread vaccination delay frequently observed in preterm children may be the cause for their higher rate of hospitalisation.

Clinical evaluation of a new rapid immunochromatographic test for detection of Bordetella pertussis antigen

A more rapid and less complicated test to diagnose pertussis is required in clinical settings. We need to detect Bordetella pertussis, which mainly causes pertussis, as early as possible, because pertussis is more likely to become severe in infants, and people around them can easily become a source of infection due to its strong infectivity. Nevertheless, methods that can detect B. pertussis rapidly and efficiently are lacking. Therefore, we developed a new immunochromatographic antigen kit (ICkit) for the early diagnosis of pertussis. The ICkit detects B. pertussis antigens in a nasopharyngeal swab without equipment and provides the result in about 15 min with a simple procedure. Additionally, a prospective study to evaluate the ICkit was conducted in 11 medical institutions, involving 195 cases with suspected pertussis. Compared with the real-time polymerase chain reaction (rPCR), the sensitivity and specificity of the ICkit were 86.4% (19/22) and 97.1% (168/173), respectively. The ICkit detected the antigen in both children and adults. Furthermore, the ICkit detected the antigen until the 25th day from the onset of cough, when rPCR detected the antigen. Thus, the ICkit demonstrated a high correlation with rPCR and would help diagnose pertussis more rapidly and efficiently.

Pertussis Toxin Promotes Pulmonary Hypertension in an Infant Mouse Model of Bordetella pertussis Infection

Pertussis, caused by Bordetella pertussis, is a reemerging disease that can produce severe disease manifestations in infants, including pulmonary hypertension (PH). B. pertussis-induced PH is a major risk factor for infection-induced death, but the molecular mechanisms promoting PH are unknown and there is no effective treatment. We examined B. pertussis-induced PH in infant and adult mouse models of pertussis by Fulton index, right heart catheterization, or Doppler echocardiogram. Our results demonstrate that B. pertussis-induced PH is age related and dependent on the expression of pertussis toxin by the bacterium. Hence, pertussis toxin-targeting treatments may ameliorate PH and fatal infant infection.

Risk factors and prediction model of severe pertussis in infants < 12 months of age in Tianjin, China

Background

To identify risk factors associated with the prognosis of pertussis in infants (< 12 months).

Methods

A retrospective study on infants hospitalized with pertussis January 2017 to June 2019. The infants were divided into two groups according to the severity of disease: severe pertussis and non-severe pertussis groups. We collected all case data from medical records including socio-demographics, clinical manifestations, and auxiliary examinations. Univariate analysis and Logistic regression were used.

Results

Finally, a total of 84 infants with severe pertussis and 586 infants with non-severe pertussis were admitted. The data of 75% of the cases (severe pertussis group, n = 63; non-severe pertussis group, n = 189) were randomly selected for univariate and multivariate logistic regression analysis. The results showed rural area [P = 0.002, OR = 6.831, 95% CI (2.013–23.175)], hospital stay (days) [P = 0.002, OR = 1.304, 95% CI (1.107–1.536)], fever [P = 0.040, OR = 2.965, 95% CI (1.050–8.375)], cyanosis [P = 0.008, OR = 3.799, 95% CI (1.419–10.174)], pulmonary rales [P = 0.021, OR = 4.022, 95% CI (1.228–13.168)], breathing heavily [P = 0.001, OR = 58.811, 95% CI (5.503–628.507)] and abnormal liver function [P < 0.001, OR = 9.164, 95% CI (2.840–29.565)] were independent risk factors, and higher birth weight [P = 0.006, OR = 0.380, 95% CI (0.191–0.755)] was protective factor for severe pertussis in infants. The sensitivity and specificity of logistic regression model for remaining 25% data of severe group and common group were 76.2% and 81.0%, respectively, and the consistency rate was 79.8%.

Conclusions

The findings indicated risk factor prediction models may be useful for the early identification of severe pertussis in infants.

Epidemiology of pertussis in Costa Rica and the impact of vaccination: A 58-year experience (1961-2018)

Costa Rica is an upper middle-income country in Central America with a vigorous public health system. We have studied the number of cases, hospitalizations, and deaths due to pertussis from 1961 to 2018, in relation to vaccine coverage. Following the introduction of the fourth and fifth doses of DTP (booster doses) in 1973 there was a marked reduction of reported pertussis. In 2002 pertussis surveillance and laboratory diagnosis were improved. In 2007, Tdap post-partum immunization was introduced and then switched to intrapartum Tdap immunization in 2011. Of these two strategies post-partum vaccination seemed to have a greater effect in decreasing hospitalizations and deaths, nevertheless, since 2011 there has been only 4 infant deaths due to pertussis.

Mortality risk factors among hospitalized children with severe pertussis

BACKGROUND

Some children hospitalized for severe pertussis need intensive care; moreover, some children die because of deterioration alone or in combination with other complications. The purpose of this study was to identify the mortality risk factors among hospitalized children with severe pertussis.

METHODS

This study evaluated the medical records of 144 hospitalized children with severe pertussis at the Guangzhou Women and Children's Medical Centre between January 2016 and December 2019.

RESULTS

The median age of patients was 2 months (IQR 1-4 months), with 90.3% of the patients aged < 6 months and 56.9% of the patients aged < 3 months. A total of 38 patients were admitted to intensive care unit (ICU), 13 patients died, and the mortality of severe pertussis was 34.2%, with patients younger than 6 weeks accounting for 76.9% of the deaths. On the multivariate analysis, the independent risk factors for death were WBC > 70.0 × 10⁹/L (odds ratio [OR], 230.66; 95% confidence interval [CI], 5.16-10,319.09 P = 0.005) and pulmonary hypertension (PH) (OR 323.29; 95% CI 16.01-6529.42; P < 0.001).

CONCLUSION

Severe pertussis mainly occurred in children aged < 3 months. The mortality of severe pertussis was 34.2%, with patients younger than 6 weeks accounting for the majority of the deaths. We recommend the first dose of diphtheria-tetanus-pertussis (DTP) should be advanced to the age of 2 months or even 6 weeks. The presence of a WBC > 70.0 × 10⁹/L and PH were the prognostic independent variables associated with death.

PTX Instructs the Development of Lung-Resident Memory T Cells in Bordetella pertussis Infected Mice

Whooping cough is a severe, highly contagious disease of the human respiratory tract, caused by Bordetellapertussis. The pathogenicity requires several virulence factors, including pertussis toxin (PTX), a key component of current available vaccines. Current vaccines do not induce mucosal immunity. Tissue-resident memory T cells (Trm) are among the first lines of defense against invading pathogens and are involved in long-term protection. However, the factors involved in Trm establishment remain unknown. Comparing two B.pertussis strains expressing PTX (WT) or not (ΔPTX), we show that the toxin is required to generate both lung CD4⁺ and CD8⁺ Trm. Co-administering purified PTX with ΔPTX is sufficient to generate these Trm subsets. Importantly, adoptive transfer of lung CD4⁺ or CD8⁺ Trm conferred protection against B. pertussis in naïve mice. Taken together, our data demonstrate for the first time a critical role for PTX in the induction of mucosal long-term protection against B. pertussis.

Pertussis Infants Needing Mechanical Ventilation and Extracorporeal Membrane Oxygenation: Single-Center Retrospective Series in Vietnam

OBJECTIVES

Pertussis is an infectious disease that causes epidemics and outbreaks and is associated with a high mortality rate, especially in infants, in both developed and developing countries. We aimed to characterize infants with pertussis with respiratory failure and shock and investigated the factors related to mortality.

DESIGN

A retrospective, observational study conducted between January 2015 and October 2020.

SETTING

This study was conducted at the Vietnam National Children's Hospital, which is a government hospital that serves as a tertiary care center in Hanoi, Vietnam.

PATIENTS

Children who fulfilled the following inclusion criteria were included: 1) admitted to the PICU, 2) less than 16 years old, 3) pertussis confirmed by real-time polymerase chain reaction, and 4) treated with mechanical ventilation due to respiratory failure and shock.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Seventy-three mechanically ventilated children (40 boys; median age, 56 d), whereas 19 patients received extracorporeal membrane oxygenation support. Twenty-six patients (36%) died including 12 who received extracorporeal membrane oxygenation. Those who received extracorporeal membrane oxygenation support had higher leukocyte counts upon admission and were more frequently diagnosed with pulmonary hypertension and stage 3 acute kidney injury. Compared with survivors, nonsurvivors showed increased heart rates, leukocyte and neutrophil counts, and lower systolic and diastolic blood pressure at admission. Increased Vasoactive-Inotropic Score, stage 3 acute kidney injury, fluid overload, the use of renal replacement therapy, and extracorporeal membrane oxygenation use were prevalent among nonsurvivors.

CONCLUSIONS

In this study, around one third of mechanically ventilated patients with pertussis died. Those who received extracorporeal membrane oxygenation had higher leukocyte counts, a higher prevalence of pulmonary hypertension, and advanced stages of acute kidney injury. Higher Vasoactive-Inotropic Score and advanced stages of acute kidney injury were associated with a greater risk of mortality.

Bordetella Adenylate Cyclase Toxin Elicits Airway Mucin Secretion through Activation of the cAMP Response Element Binding Protein

The mucus layer protects airway epithelia from damage by noxious agents. Intriguingly, Bordetella pertussis bacteria provoke massive mucus production by nasopharyngeal epithelia during the initial coryza-like catarrhal stage of human pertussis and the pathogen transmits in mucus-containing aerosol droplets expelled by sneezing and post-nasal drip-triggered cough. We investigated the role of the cAMP-elevating adenylate cyclase (CyaA) and pertussis (PT) toxins in the upregulation of mucin production in B. pertussis-infected airway epithelia. Using human pseudostratified airway epithelial cell layers cultured at air–liquid interface (ALI), we show that purified CyaA and PT toxins (100 ng/mL) can trigger production of the major airway mucins Muc5AC and Muc5B. Upregulation of mucin secretion involved activation of the cAMP response element binding protein (CREB) and was blocked by the 666-15-Calbiochem inhibitor of CREB-mediated gene transcription. Intriguingly, a B. pertussis mutant strain secreting only active PT and producing the enzymatically inactive CyaA-AC^– toxoid failed to trigger any important mucus production in infected epithelial cell layers in vitro or in vivo in the tracheal epithelia of intranasally infected mice. In contrast, the PT^– toxoid-producing B. pertussis mutant secreting the active CyaA toxin elicited a comparable mucin production as infection of epithelial cell layers or tracheal epithelia of infected mice by the wild-type B. pertussis secreting both PT and CyaA toxins. Hence, the cAMP-elevating activity of B. pertussis-secreted CyaA was alone sufficient for activation of mucin production through a CREB-dependent mechanism in B. pertussis-infected airway epithelia in vivo.

Clinical characteristics of 967 children with pertussis: a single-center analysis over an 8-year period in Beijing, China

The purpose of this study is to understand children’s clinical characteristics with pertussis and analyze risk factors on critical pertussis patients. Demographic data from patients with pertussis at Children’s Hospital affiliated to the Capital Institute of Pediatrics between March 2011 and December 2018 were collected. We retrospectively gathered more information with the positive exposure, vaccination, antibiotic usage before diagnosis, clinical manifestation, laboratory tests, therapy, and complications for hospitalized children. We divided the patients into severe and non-severe groups, comparing related factors and clinical characteristics among each group. In particular, we summarize the clinical features of the severe patients before aggravation. A total of 967 pertussis cases were diagnosed, of which 227 were hospitalized. The onset age younger than 3 months old accounted for the highest proportion, and 126 patients received hospitalization. For those patients, the incidence of post-tussive vomiting, paroxysmal cyanosis, post-tussive heart rate decrease, hypoxemia, severe pneumonia, and mechanical ventilation was significantly higher than that in the ≥ 3-month-old group (p < 0.05). Among 227 hospitalized patients, 54 suffered from severe pertussis. Risk factors for severe patients included early age of onset, pathogen exposure, and unvaccinated status. Cough paroxysms, post-tussive vomiting, paroxysmal cyanosis, facial flushing/cyanosis/fever during cough, increased WBC, and chest X-ray revealing pneumonia/consolidation/atelectasis were important indications of severe pertussis. Unvaccinated status was an independent risk factor for severe pertussis. The most vulnerable population was infants < 3 months old to pertussis, and may be on the severe end of the disease. Pediatricians must detect and treat severe cases promptly and recommend timely vaccination for all eligible children.

The Effect of Tetanus-Diphtheria-Acellular-Pertussis Immunization During Pregnancy on Infant Antibody Responses: Individual-Participant Data Meta-Analysis

Background

Immunization with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in pregnancy is increasingly recommended. We determined the effect of Tdap immunization in pregnancy on infants' vaccine responses.

Methods

Individual-participant data meta-analysis of ten studies (n=1884) investigating infants' antibody response to routine immunizations following Tdap immunization in pregnancy was performed. Geometric mean ratios (GMRs) of antigen-specific immunoglobulin G (IgG) levels were calculated using mixed-effects models. Seroprotection rates were compared using chi-squared tests.

Results

Infants of Tdap-immunized women had significantly lower IgG against pertussis toxin (GMR 0.65; 95%CI 0.57-0.74), filamentous haemagglutinin (FHA) (0.68; 0.53-0.87), pertactin (0.65; 0.58-0.72) and fimbria 2/3 (FIM2/3) (0.41; 0.32-0.52) after primary immunization, compared with infants of unimmunized women. These lower levels persisted after booster immunization for FHA (0.72; 0.61-0.84) and FIM2/3 (0.53; 0.29-0.96). After primary immunization, infants of Tdap-immunized women had lower seroprotection rates against diphtheria (90% [843/973] vs 98% [566/579]; p<0.001) and invasive pneumococcal disease (IPD) caused by 5 Streptococcus pneumoniae (SPN) serotypes (SPN5, SPN6B, SPN9V, SPN19A, SPN23F), and higher seroprotection rates against Haemophilus influenzae type b (short-term and long-term seroprotection rates, 86%[471/547] vs 76%[188/247] and 62%[337/547] vs 49%(121/247), respectively, all p=0.001). After booster immunization, seroprotection rates against diphtheria and tetanus were 99% (286/288) and (618/619) in infants of Tdap-immunized women, respectively.

Conclusions

Infants of Tdap-immunized women in pregnancy had lower IgG levels against pertussis, diphtheria and some SPN serotypes after their immunization compared with infants of unimmunized women. Enhanced surveillance of pertussis, diphtheria and IPD in infants is needed to determine the clinical significance of these findings.

Systematic Review Registration

CRD42017079171.

Is it time to administer acellular pertussis vaccine to childbearing age/pregnant women in all areas using whole-cell pertussis vaccination schedule?

Background:

Whole-cell pertussis (wP) vaccine administration is still advocated for children under 7 years of age in Iran. However, there is no recommendation for the administration of a dose of tetanus, diphtheria, and acellular pertussis (Tdap) vaccine to childbearing age/pregnant women in the Iranian vaccination program and it has increased the risk of infection through waning immunity during women’s childbearing age life. The study aimed to assess the levels of anti-Bordetella pertussis antibodies in childbearing age women of different ages in Iran.

Methods:

A cross-sectional study was conducted on a total number of 360 childbearing age women divided into six age groups, with 5-year intervals from 15 to 45 years old, in 2018–2019. Then, the levels of immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG) antibodies against B. pertussis were evaluated using enzyme-linked immunosorbent assay (ELISA). The IBM SPSS Statistics software (version 16.0) (SPSS Inc., Chicago, IL, USA) was used for data analysis.

Results:

The mean age of the participants was 30.01 ± 8.35 years (range 14–45 years). All the cases were IgM negative, but two IgA-positive individuals (in the age groups of 14–19 and 30–34 years) were reported. Overall, 239 (66.4%) cases were IgG positive. The mean age of IgG-positive cases was 30.37 ± 8.37 years. The IgG-positive cases were mostly in the age groups of 30–34 and 35–39 years [43 (71.1%)]. The odds of IgG positivity were 1.97. The highest odds of IgG positivity were seen in 30–34 and 35–39 years groups (2.52) and the lowest odds were seen in the 20–24 and 25–29 years groups (1.60). Using the Jonckheere–Terpstra test, the increasing trend of IgG changes in different age groups was not statistically significant (Tπ=5.78, p = 0.09).

Conclusion:

The infants of women of childbearing age might be prone to pertussis in countries using the wP vaccination schedule. It is suggested to administer a dose of Tdap to women before or during pregnancy to increase the immunity of their infants against this disease during early infancy.

Critical pertussis: A multi-centric analysis of risk factors and outcomes in Oman

OBJECTIVES

To identify risk factors and outcomes of patients with critical pertussis.

DESIGN

Retrospective observational cohort study.

SETTING

Sultan Qaboos University Hospital and The Royal Hospital, Muscat, Oman.

SUBJECTS

Children aged <13 years presenting to the emergency departments and diagnosed with laboratory-confirmed pertussis by polymerase chain reaction between January 2013 and December 2018.

MEASUREMENTS AND MAIN RESULTS

In total, 157 patients were diagnosed with pertussis, of which 12% (n = 19) had critical pertussis. Patients with critical pertussis had a higher white blood cell count (WBCC) [adjusted odds ratio (aOR) 1.05; 95% confidence interval (CI) 1.02-1.08; P = 0.003], absolute lymphocyte count (ALC) (aOR 1.08; 95% CI 1.03-1.15; P = 0.004) and absolute neutrophil count (ANC) (aOR 1.05; 95% CI 1.01-1.10; P = 0.032) than patients with non-critical pertussis, even after multi-variate adjustment. The area under the curve for discriminatory accuracy of laboratory variables was 0.75 (95% CI 0.65-0.85), 0.74 (95% CI 0.64-0.84) and 0.72 (95% CI 0.60-0.83) for maximum WBCC, ALC and ANC, respectively, with Youden's cut-off values of 31.5 × 10⁹/L, 19.9 × 10⁹/L and 5.0 × 10⁹/L, respectively.

CONCLUSIONS

In children, higher WBCC, ALC and ANC were significant predictors of critical pertussis. A cut-off level of 31.5 × 10⁹/L for WBCC was associated with critical pertussis.

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.

[Research advances in the treatment strategies for severe pertussis in children]

At present, effective antibiotics and comprehensive symptomatic/supportive treatment as early as possible are mainly used for the treatment of severe pertussis in clinical practice. However, some children with severe pertussis have unsatisfactory response to commonly used drugs and treatment measures in the intensive care unit and thus have a high risk of death. Studies have shown that certain treatment measures given in the early stage, such as exchange transfusion, may help reduce deaths, but there is still a lack of uniform implementation norms. How to determine the treatment regimen for severe pertussis and improve treatment ability remains a difficult issue in clinical practice. This article reviews the advances in the treatment of severe pertussis, in order to provide a reference for clinical treatment and research.

Effect of Macrolides and β-lactams on Clearance of Bordetella pertussis in the Nasopharynx in Children With Whooping Cough

OBJECTIVE

The purpose of the current study is to investigate the bactericidal effect of macrolides and β-lactams on Bordetella pertussis (B. pertussis) in the nasopharynx and provide guidance for treating macrolides-resistant B. pertussis infections.

METHODS

Patients with whooping cough was diagnosed by culture of nasopharynx swabs between January 2016 to December 2018. B. pertussis was identified using specific antisera against pertussis and parapertussis. Drug susceptibility test was carried out using the E-test method. The clearance of B. pertussis in nasopharynx at 7 and 14 days into and posttreatment with macrolides, and β-lactams was compared.

RESULTS

A total of 125 B. pertussis samples were collected from patients who received single antibiotic treatment. Among those isolates, 62.4% (78/125) had high resistance with minimum inhibitory concentrations greater than 256 mg/L for erythromycin and azithromycin. The MIC90 of piperacillin, cefoperazone-sulbactam, meropenem, ampicillin, ceftriaxone, ceftazidime and trimethoprim-sulfamethoxazole for these isolates was <0.016, 0.094, 0.094, 0.19, 0.19, 0.25 and 0.75 mg/L, respectively. The clearance rate with β-lactams treatment (68.8%, 44/64) was significantly higher than that with macrolides treatment at 14 days posttreatment (50.8%, 31/61) (χ2 = 4.18, P = 0.04). Macrolides had a better clearance rate at 7 days posttreatment than β-lactams (χ2 = 4.49, P = 0.03) for macrolides-sensitive isolates and a worse clearance rate for macrolides-resistant isolates.

CONCLUSION

B. pertussis isolates had a high-resistant rate for macrolides in our study. Macrolides are the first choice for treating pertussis caused by macrolides-sensitive strains, and some β-lactams such as piperacillin should be considered as alternative antibiotics for treatment of macrolides-resistant B. pertussis infection.

Protection of the Newborn Through Vaccination in Pregnancy

Newborns and infants are at risk for severe infections with some pathogens (eg, Bordetella pertussis, influenza, respiratory syncytial virus, group B Streptococcus) during early life. To decrease this window of high susceptibility to some infections during early life and protect young infants, vaccination in pregnancy against some vaccine-preventable diseases (eg, influenza, pertussis, tetanus) has been recommended in an increasing number of countries with notable success. In addition, recent advances have been made in developing vaccines for pregnant women with the aim of reducing the respiratory syncytial virus and group B Streptococcus burden in infancy. In this article, we review the vaccines currently recommended during pregnancy and their benefits to newborns and infants. We also discuss progress made in the development of other vaccines that are expected to be evaluated in pregnant women in the near future.

Clinical and Epidemiologic Characteristics of Pertussis in Hospitalized Children: A Prospective and Standardized Long-term Surveillance Study

BACKGROUND

Surveillance of incidence and severity of pertussis is key to control success and shortcomings of vaccination programs followed by adaptations of recommendations if necessary. In Switzerland, nationwide reporting of hospitalizations due to pertussis in children has a long tradition and resumed in 2013 to evaluate the effects of pertussis immunization in pregnancy introduced in 2013.

METHODS

Since 2013, all patients <16 years of age hospitalized with suspected or proven pertussis have been reported to the Swiss Pediatric Surveillance Unit. Patient data comprising clinical and epidemiologic characteristics and laboratory confirmation were assessed in a standardized fashion, and case definitions were applied to all cases reported until the end of 2019.

RESULTS

Two hundred thirteen of 294 cases were valid cases of pertussis. Of these, 168 (79%) occurred in <6-month-old infants. Mean duration of hospitalization was 8 days (median 5, range 2-47) overall and highest in neonates (14.2 days); 85% of all patients had ≥1 complication, most commonly cyanosis and dyspnea, especially in infants. Overall, case fatality rate was 1.4% (8.7% in neonates). Only 4 (2%) of 168 mothers of infants <6 months had been vaccinated during pregnancy; 14 (12%) of 112 patients with precise records of immunization had completed their primary series and were up-to-date for age.

CONCLUSIONS

Despite a decline of cases associated with the introduction of immunization against pertussis in pregnancy, control of the disease remains challenging, mainly due to failure to vaccinate rather than vaccine failure.

Pharmacotherapy for Bordetella pertussis infection. II. A synthesis of clinical sciences

Despite the plethora of studies that have examined laboratory susceptibility testing for Bordetella pertussis, assessments of treatment have lagged far behind both in quality and quantity. Macrolides and trimethoprim/sulfamethoxazole historically served the needs of both treatment and prevention, albeit there is still controversy about the degree of protection measured both bacteriologically and clinically. As high-level macrolide resistance has emerged in some geographic regions and since macrolides have been the mainstay of therapy, alternative antibiotics need to be defined for pertussis. In vitro susceptibility testing suggests the potential for several alternatives to macrolides, including trimethoprim/sulfamethoxazole, specific β-lactam agents, chloramphenicol, some quinolones and possibly some tetracyclines. For the latter antibiotics, more clinical studies for treatment and prophylaxis are required in to order to establish bacteriological-clinical correlates for outcome. In the interim, if the clinical circumstances mandate the use of proposed interim alternatives to macrolides, outcomes should be assessed with test of cure by culture, since genetic amplification technologies do not discriminate bacterial viability. Whereas there may be debate in regard to using placebo or macrolides as the controls for alternative antibiotic therapy in geographies where most B. pertussis isolates are antibiotic-susceptible, both placebo and macrolide controls should be assessed along with alternative antibiotics in well-designed controlled studies in regions pressured by macrolide resistance. Outcomes of clinical response and epidemiological patterns of disease should continue to be monitored given the degree of macrolide resistance that is emerging.

Leukoreduction and hydroxyurea in malignant pertussis: A case series

We report five cases of malignant pertussis, a rare but life-threatening illness. Current therapies include supportive care and leukoreduction. Notably, leukoreduction might be more effective when initiated prior to the development of organ failure and pulmonary hypertension.

Risk factors associated with death in infants <120 days old with severe pertussis: a case-control study

Background and purpose

Pertussis is a serious infectious disease in young infants, and severe cases frequently cause death. Our study explored risk factors for death from severe pertussis.

Method

A case-control study of infants with severe pertussis admitted to the paediatric intensive care unit (PICU) in the Children’s Hospital of Chongqing Medical University, China, from January 1, 2013, to June 30, 2019, was conducted. Pertussis was confirmed by clinical features and laboratory examinations. Severe pertussis was defined as patients with pertussis resulting in PICU admission or death. To understand the risk factors for death, we compared fatal and nonfatal cases of severe pertussis in infants aged < 120 days by collecting clinical and laboratory data.

Results

The participants included 63 infants < 120 days of age with severe pertussis. Fifteen fatal cases were confirmed and compared with 44 nonfatal severe pertussis cases, Four patients with termination of treatment were excluded. In the univariate analysis, the risk factors associated with death included apnoea (P = 0.001), leukocytosis (white blood cell (WBC) count≥30 × 10⁹/L (P = 0.001) or ≥ 50 × 10⁹/L (P = 0)), highest lymphocyte count (P = 0), pulmonary hypertension (P = 0.001), and length of PICU stay (P = 0.003). The multivariate analysis revealed that apnoea (OR 23.722, 95%CI 2.796–201.26, P = 0.004), leukocytosis (OR 63.708, 95%CI 3.574–1135.674, P = 0.005) and pulmonary hypertension (OR 26.109, 95%CI 1.800–378.809, P = 0.017) were significantly associated with death.

Conclusion

Leukocytosis and pulmonary hypertension exhibited the greatest associations with death in infants with severe pertussis admitted to the PICU. Vaccination is still the most effective protection method against pertussis.

Clinical and epidemiological features of pertussis in Salvador, Brazil, 2011-2016

Pertussis, a severe respiratory infection caused by Bordetella pertussis, is distributed globally. Vaccination has been crucial to annual reductions in the number of cases. However, disease reemergence has occurred over the last decade in several countries, including Brazil. Here we describe the clinical and epidemiological aspects of suspected pertussis cases in Salvador, Brazil, and evaluate factors associated with case confirmation. This descriptive and retrospective study was conducted in the five hospitals in Salvador that reported the highest number of pertussis cases between 2011-2016. Demographic and clinical data were recorded for each patient. Bivariate analysis was performed to evaluate differences between groups (confirmed vs. unconfirmed cases) using Pearson's Chi-square test or Fisher's exact test. Results: Of 529 suspected pertussis cases, 29.7% (157/529) were confirmed by clinical, clinical-epidemiological or laboratory criteria, with clinical criteria most frequently applied (63.7%; 100/157). Unvaccinated individuals (43.3%; 68/157) were the most affected, followed by age groups 2-3 months (37.6%; 59/157) and <2 months (31.2%; 49/157). Overall, ≤50% of the confirmed cases presented a complete vaccination schedule. All investigated cases presented cough in association with one or more symptoms, especially paroxysmal cough (66.9%; 105/529) (p = 0.001) or cyanosis (66.2%; 104/529) (p<0.001). Our results indicate that pertussis occurred mainly in infants and unvaccinated individuals in Salvador, Brazil. The predominance of clinical criteria used to confirm suspected cases highlights the need for improvement in the laboratory tools used to perform rapid diagnosis. Fluctuations in infection prevalence demonstrate the importance of vaccination strategies in improving the control and prevention of pertussis.

Establishment and application of a multiple cross displacement amplification combined with nanoparticles-based biosensor method for the detection of Bordetella pertussis

Background

Bordetella pertussis is the causative agent of pertussis, a respiratory tract infectious disease.

Efficient techniques for detection of B. pertussis isolates are important for clinical diagnosis.

Multiple cross displacement amplification (MCDA), a novel isothermal amplification based molecular detection method, has been developed to overcome the technical drawback of the current methods in recent years. This aim of this study is to develop a MCDA with Nanoparticles-based Lateral Flow Biosensor (MCDA-LFB) for the detection of B. pertussis.

Results

A set of 10 primers based on the pertussis toxin (PT) promoter region sequence of B. pertussis was designed. The B. pertussis-MCDA-LFB assay was successfully established and optimized at 64 °C for reaction of 40 min. The detection limit was determined as 10 fg/reaction of pure DNA, and no cross-reactions to non-B. pertussis strains were observed, based on the specificity validation. The whole operation, ranging from template preparation to result reporting, could be completed within 70 min without requirement of costly equipment. The B. pertussis-MCDA-LFB in clinic sample detection yielded identical positive rates with traditional culture and showed higher sensitivity than conventional PCR. The results of MCDA-LFB are easier to read due to the usage of LFB.

Conclusions

The isothermal amplification based MCDA-LFB established in the present study is a specific, sensitive, rapid and economical technique for the detection of B. pertussis.

Severe Pertussis Infections in the United States, 2011-2015

Background

The incidence of pertussis in the United States has increased in recent years. While characteristics of severe pertussis infection have been described in infants, fewer data are available in older children and adults. In this analysis, we characterize pertussis infections in hospitalized patients of all ages.

Methods

Cases of pertussis with cough onset from 1 January 2011 through 31 December 2015 from 7 US Emerging Infections Program Network states were reviewed. Additional information on hospitalized patients was obtained through abstraction of the inpatient medical record. Descriptive and multivariable analyses were conducted to characterize severe pertussis infection and identify potential risk factors.

Results

Among 15942 cases of pertussis reported, 515 (3.2%) were hospitalized. Three hospitalized patients died. Infants aged <2 months accounted for 1.6% of all pertussis cases but 29.3% of hospitalizations. Infants aged 2–11 months and adults aged ≥65 years also had high rates of hospitalization. Infants aged <2 months whose mothers received acellular pertussis during the third trimester and children aged 2 months to 11 years who were up to date on pertussis-containing vaccines had a 43%–66% reduced risk of hospitalization. Among adolescents aged 12–20 years, 43.5% had a history of asthma, and among adults aged ≥65 years, 26.8% had a history of chronic obstructive pulmonary disease.

Conclusions

Individuals at the extreme ends of life may be the most vulnerable to severe pertussis infections, though hospitalization was reported across all age groups. Continued monitoring of severe pertussis infections will be important to help guide prevention, control, and treatment options.

Analysis of Multiple Factors Involved in Pertussis-Like Coughing

Objectives. To identify risk factors associated with the prognosis of pertussis-like coughing. Methods. A retrospective study on children hospitalized with pertussis-like coughing from 2018 to 2019. We collected all the case data from medical records including age, gender, vaccination, clinical symptoms, complication, pathogens, white blood cell (WBC) count, lymphocyte ratio, application of macrolide antibiotics, usage of sulfamethoxazole, and usage of inhaled glucocorticoids. Logistic regression was used in this study. Results. A total of 213 hospitalized children with pertussis-like coughing were included in this study. About 70 children were cured within 2 weeks. One120 children were cured from 2 weeks to 3 months, including cases of initial attack and relapse. Symptoms lasting longer than 3 months accounts for 10.8%. Bordetella pertussis, WBC count >20 × 10⁹/L and lymphocyte ratio >60% were associated with poor prognosis (P < .05). Conclusions. Bordetella pertussis, WBC count, and lymphocyte ratio are independent risk factors for poor prognosis.

Burden of Children Hospitalized With Pertussis in Canada in the Acellular Pertussis Vaccine Era, 1999-2015

BACKGROUND

Recent increases in pertussis morbidity and mortality rates among young infants have led to a recommendation in some countries for vaccination against pertussis during pregnancy. Having data on the burden of pediatric pertussis in a large population over time is important for establishing the true burden of disease in the acellular pertussis (aP) vaccine era. Here, we describe age-specific epidemiology and morbidity and mortality rates in children hospitalized with pertussis over 17 years across Canada in the aP vaccine era.

METHODS

Patients aged ≤16 years who were admitted to 1 of 12 pediatric tertiary-care hospitals across Canada between 1999 and 2015 with confirmed (laboratory-confirmed or epidemiologically linked) or probable (clinically diagnosed) pertussis were included.

RESULTS

Overall, 1402 patients with pertussis were included. Infants aged <2 months had the highest mean annual incidences of pertussis hospitalization and intensive care unit (ICU) admission (116.40 [95% confidence interval (CI), 85.32-147.49] and 33.48 [95% CI, 26.35-40.62] per 100 000 population, respectively). The overall proportion of children who required ICU admission was 25.46%, and the proportion was highest in infants aged <2 months (37.90%). Over the span of this study, 21 deaths occurred. Age of <16 weeks, prematurity, encephalopathy, and a confirmed pertussis diagnosis were independent risk factors for ICU admission. Age of <4 weeks, prematurity, and female sex were independent risk factors for death.

CONCLUSIONS

In the aP vaccine era, endemic pertussis still contributes considerably to childhood morbidity and death, particularly in infants aged <2 months. Vaccination against pertussis during pregnancy has the potential to reduce this disease burden.