Global burden of pertussis in 204 countries and territories, from 1990 to 2019: results from the Global Burden of Disease Study 2019.

OBJECTIVES: This study aimed to examine the impact of pertussis on the global, regional, and national levels between 1990 and 2019. METHODS: Data on pertussis on a global scale from 1990 to 2019 were collected from the 2019 Global Burden of Disease Study. We performed a secondary analysis to report the global epidemiology and disease burden of pertussis. RESULTS: During the period spanning from 1990 to 2019, pertussis exhibited a steady global decline in the age-standardized incidence rate (ASIR), age-standardized disability-adjusted life years rate (ASYR), and age-standardized death rate (ASDR). Nevertheless, upon delving into an in-depth analysis of various regions, it was apparent that ASIR in southern sub-Saharan Africa, ASYR and ASDR in high-income North America, and ASDR in Western Europe and Australasia, were witnessing an upward trajectory. Moreover, a negative correlation was observed between the Socio­demographic Index (SDI) and burden inflicted by pertussis. Notably, the incidence of pertussis was comparatively lower in men than in women, with 0-4-year-olds emerging as the most profoundly affected demographic. CONCLUSION: The global pertussis burden decreased from 1990 to 2019. However, certain regions and countries faced an increasing disease burden. Therefore, urgent measures are required to alleviate the pertussis burden in these areas.

Economic burden of pertussis in children: A single-center analysis in Hangzhou, China.

The "reemergence of pertussis" has elicited international concerns, occurring paradoxically amidst the expansion of immunization programs. This study was aimed to evaluate quantitatively the economic burden and identify the determinants that influence the cost associated with treating pertussis in Chinese children. We evaluated the economic burden by Chinese children diagnosed with pertussis at the Children's Hospital, Zhejiang University School of Medicine in 2022. Direct medical expenses and the utilization of medical resources attributed to pertussis were calculated. A generalized linear regression model was applied to analyze the determinants that were associated with the direct medical expenses among patients. Among the 1110 pertussis patients included in the study, 1060 were outpatients and 50 were inpatients. The average direct medical cost was ¥1878.70(i.e. $279.33). Living in urban areas (OR:1.27, p = .04), complications (OR:1.40, p < .001), hospitalization (OR:10.04, p < .001), and ≥ 3 medical visits (OR:3.71, p < .001) were associated with increased direct medical expenses. Having received four doses of the pertussis vaccine was associated with reduced direct medical expenses (OR:0.81, p = .04). This study underscores a substantial economic burden of pertussis in Hangzhou, with pronounced implications for patients residing in urban areas, experiencing complications, requiring hospitalization, having multiple medical consultations, or lacking comprehensive pertussis vaccination.

Maternal Vaccination in Pregnancy: An Assessment of Influenza, Pertussis, and COVID-19 Vaccination Rates in Cracow, Poland.

BACKGROUND Maternal vaccination during pregnancy reduces the risk of severe course and complications from infections both for the mother and her child. As information regarding immunization status of pregnant women with recommended vaccines in Poland is scarce, this questionnaire-based study aimed to identify influenza, pertussis (whooping cough), and COVID-19 vaccination in 205 pregnant women in Cracow, Poland, between February and April 2023. Another objective was to assess whether any of the maternal factors might influence women's decision to inoculate during pregnancy. MATERIAL AND METHODS An anonymous and self-reported questionnaire developed specifically for this study was disseminated among postpartum women, who gave birth and were hospitalized at the Department of Obstetrics and Perinatology of the University Hospital in Cracow, Poland, between February and April 2023. Study participants were asked about their basic sociodemographic and obstetric data, as well as their immunization status regarding influenza, pertussis, and COVID-19 during their most recent pregnancy. RESULTS Only 12.2% and 23.4% of study participants received influenza and pertussis vaccinations, respectively, during pregnancy, while 61.5% of pregnant women reported vaccination with at least 2 doses of the mRNA COVID-19 vaccine. Features including type of occupation, place of residence, gravidity, and parity were statistically significant (P.

Cost-effectiveness analysis of pertussis booster vaccination for adolescents in Japan.

INTRODUCTION: In Japan, the introduction of a fifth diphtheria-tetanus-acellular pertussis (DTaP) vaccination has been considered, and adolescents aged 11-12 years old who are currently receiving the diphtheria-tetanus (DT) vaccine are one candidate group. We analyze the cost-effectiveness of replacing the DT vaccine with the DTaP vaccine for 11-year-old adolescents and investigate the indirect effect of vaccinated adolescents on unvaccinated infant siblings. We undertake two analyses using high- and low-morbidity pertussis cases, and based on the results, present suggestions for pertussis prevention in the post-COVID-19 pandemic era. METHOD: We used the number of pertussis cases in 2019 as the high-morbidity case and the average number of cases in 2020-2021 as the low-morbidity case, and evaluated the incremental cost-effectiveness ratio (ICER) of the DTaP strategy to the DT strategy based on quality-adjusted life years (QALYs). The economic model contained adolescent and infant sub-models. The indirect effect for infants was considered as the probability of unvaccinated infants avoiding pertussis infection from their vaccinated siblings. RESULTS: The ICER from the payers' perspective was Japanese yen (JPY) 4,254,515 per QALY gained in the high-morbidity case and JPY 62,546,776 per QALY gained in the low-morbidity case. The sensitivity analysis showed that the utility of pertussis had the greatest impact on the ICER, with a 60.58% and 0% probability that the ICER was less than JPY 5 million per QALY gained in the high-morbidity case and low-morbidity case, respectively. CONCLUSION: The cost-effectiveness of replacing the DT vaccine with the DTaP vaccine is affected by the level of pertussis morbidity, with the ICER becoming more favorable in the high-morbidity case. The indirect effect has little impact on the ICER. Thus, policy-makers should continue to monitor the pertussis epidemic in the post-COVID-19 era, and determine the need to introduce a booster based on perceived trends.

The impact of maternal pertussis vaccination recommendation on infant pertussis incidence and mortality in the USA: an interrupted time series analysis.

BACKGROUND: Pertussis is a contagious respiratory disease. Maternal tetanus-diphtheria-acellular pertussis vaccination during pregnancy has been recommended by the United States Centres for Disease Control (US CDC) Advisory Committee on Immunization Practices (ACIP) for unvaccinated pregnant women since October 2011 to prevent infection among infants; in 2012, ACIP extended this recommendation to every pregnancy, regardless of previous vaccination status. The population-level effect of these recommendations on infant pertussis is unknown. This study aimed to examine the impact of the 2011/2012 ACIP pertussis recommendation on pertussis incidence and mortality among US infants. METHODS: We used monthly data on pertussis deaths among infants aged <1 year between January 2005 and December 2017 in the CDC Death Data and yearly infant pertussis incidence data from the CDC National Notifiable Disease Surveillance System to perform an interrupted time series analysis, accounting for the passage of the Affordable Care Act. RESULTS: This study included 156 months of data. A potential decline in trend in infant pertussis incidence was noted during the post-recommendations period. No appreciable differences in trend were found in population-level infant pertussis mortality after the guideline changes in both adjusted and unadjusted models. Results were similar for all mortality sensitivity analyses. CONCLUSIONS: The 2011/2012 ACIP maternal pertussis vaccination recommendations were not associated with a population-level change in the trend in mortality, but were potentially associated with a decrease in incidence in the USA between 2005 and 2017.

Increased Burden of Pertussis Among Adolescents and Adults With Asthma or COPD in the United States, 2007 to 2019.

BACKGROUND: Individuals with chronic respiratory illnesses may be at higher risk of pertussis infection and severe pertussis than those without. RESEARCH QUESTION: What is the incidence of pertussis and pertussis complications in cohorts with preexisting asthma or COPD vs age- and sex-matched control patients from the general population in the United States? STUDY DESIGN AND METHODS: This observational, retrospective study included individuals aged ≥ 10 years from an administrative health claims system between 2007 and 2019. Individuals with preexisting asthma or COPD were matched with control patients from the general population. The incidence of pertussis infections and pertussis-related complications were assessed overall and by age. The incidence of asthma or COPD exacerbations was also assessed before and after diagnosis of pertussis. RESULTS: In the general population, incidence per 100,000 person-years of pertussis infection ranged from 5.33 in 2007 to 13.04 in 2012, with highest (all years) in those aged 10 to 17 years. The risk of pertussis was higher for the asthma (rate ratio, 3.57; 95% CI, 3.25-3.92) and COPD cohorts (rate ratio, 1.83; 95% CI, 1.57-2.12) than the general population. Those with asthma or COPD had a 4.12-fold (95% CI, 3.16-5.38) and 2.82-fold (95% CI, 2.14-3.27) increased risk of pertussis with complications than the general population, respectively. Exacerbations were most frequent 30 days before pertussis diagnosis (incidence rate [IR], 25%) in the asthma cohort and 30 days before (IR, 26%) and after (IR, 22%) pertussis diagnosis, remaining elevated for 180 days after diagnosis, in the COPD cohort. INTERPRETATION: Among these insured individuals, asthma or COPD increased the risk for pertussis disease and complications vs the general population. COPD and asthma exacerbations were observed most frequently within 30 days of receiving a pertussis diagnosis and remained elevated, suggesting a long-term effect of pertussis in the COPD cohort.

Cost of illness due to pertussis in adults ≥50 years of age in the United Kingdom.

BACKGROUND: Pertussis is an endemic respiratory tract infection caused by Bordetella pertussis that may affect all individuals from infants to older adults. Pertussis incidence in adults is often underreported and in various countries, including the United Kingdom (UK), there are evidence gaps on pertussis-associated economic burden in the older adult population. We aimed to quantify the economic burden of pertussis in adults aged ≥50 years in the UK. METHODS: A cost-of-illness study was conducted to estimate the cost of pertussis from a societal perspective. We utilized a sum diagnosis cost approach in which costs related to infection with pertussis were included. Medical, patient, and indirect costs were calculated individually and combined to calculate total costs. A framework was developed to assess costs for consecutive age groups from 50-54 years of age to ≥85 years of age. Sensitivity and scenario analyses were used to assess analysis uncertainty. RESULTS: The base-case analysis estimated the total annual economic burden of pertussis to be approximately £238 million (M). This comprised approximately £159 M in indirect costs, £66 M in medical costs, and £13 M in patient costs. Costs for the age group 55-59 years had the highest impact on the economic burden, with approximately £79 M in total annual costs. Visits to general practitioners and nurses were the largest contributors to medical costs (∼£37 M) followed by inpatient visits (∼£21 M). Transportation costs (∼£10 M) were the major patient costs. Productivity loss (∼£71 M) and leisure time loss (∼£72 M) had comparable contributions to annual indirect costs. Sensitivity and scenario analyses suggested that incidence rates, indirect costs, and underreporting estimates had the highest impact on outcomes. CONCLUSION: Total cost of pertussis in the UK among adults ≥50 years of age is substantial and highest for adults 55-59 years of age. Indirect costs were the main contributors to the economic burden.

Estimating the pertussis burden in adolescents and adults in the United States between 2007 and 2019.

We developed a machine learning algorithm to identify undiagnosed pertussis episodes in adolescent and adult patients with reported acute respiratory disease (ARD) using clinician notes in an electronic healthcare record (EHR) database. Here, we utilized the algorithm to better estimate the overall pertussis incidence within the Optum Humedica clinical repository from 1 January 2007 through 31 December 2019. The incidence of diagnosed pertussis episodes was 1-5 per 100,000 annually, consistent with data registered by the US Centers for Disease Control and Prevention (CDC) over the same time period. Among 18,573,496 ARD episodes assessed, 1,053,946 were identified (i.e. algorithm-identified) as likely undiagnosed pertussis episodes. Accounting for these undiagnosed pertussis episodes increased the estimated pertussis incidence by 110-fold on average (34-474 per 100,000 annually). Risk factors for pertussis episodes (diagnosed and algorithm-identified) included asthma (Odds ratio [OR] 2.14; 2.12-2.16), immunodeficiency (OR 1.85; 1.78-1.91), chronic obstructive pulmonary disease (OR 1.63; 1.61-1.65), obesity (OR 1.44; 1.43-1.45), Crohn's disease (OR 1.39; 1.33-1.45), diabetes type 1 (OR 1.21; 1.17-1.24) and type 2 (OR 1.12; 1.1-1.13). Of note, all these risk factors, except Crohn's disease, increased the likelihood of severe pertussis. In conclusion, the incidence of pertussis in the adolescent and adult population in the USA is likely substantial, but considerably under-recognized, highlighting the need for improved clinical awareness of the disease and for improved control strategies in this population. These results will help better inform public health vaccination and booster programs, particularly in those with underlying comorbidities.

Incidence and Healthcare Burden of Pertussis among Older Adults with and without Pre-Existing Chronic Obstructive Pulmonary Disease or Asthma in South Korea.

A retrospective cohort study was conducted to examine trends in the incidence and burden of pertussis among adults ≥50 years in South Korea, with/without pre-existing chronic obstructive pulmonary disease (COPD) or asthma. The nationwide Health Insurance Review and Assessment Service (HIRA) database was used to identify patients ≥50 years diagnosed with pertussis (2009-2018). Mean annual incidence of pertussis per 100 000 persons and overall mean incidence rate ratios (IRR) were calculated for patients with pre-existing COPD or asthma versus those with neither. Incremental healthcare costs (all-cause and pertussis-related) and healthcare utilisation (number of outpatient visits, emergency room visits, and number and length of hospitalisations) up to 12 months after, compared to 3 months before pertussis diagnosis, were also measured for each group (matched on sex, age, and Charlson Comorbidity Index). Of 1011 pertussis cases, 175 had asthma, 96 had COPD (not mutually exclusive), and 796 had neither. Overall mean pertussis incidence was 2.5, 3.4, and 0.5 for adults with pre-existing COPD, asthma, and those with neither. IRR (95% confidence interval) of pertussis for adults with pre-existing COPD and asthma was 4.9 (4.0-|6.1) and 6.7 (5.7-7.9). Both COPD-pertussis and asthma-pertussis groups had higher mean incremental all-cause costs and length of hospitalisations than the general-pertussis group 3 months following pertussis diagnosis. In conclusion, individuals ≥50 years in South Korea with pre-existing COPD or asthma were at an increased risk of being diagnosed with pertussis and had higher healthcare resource utilisation than those without these conditions.

The incidence, duration, risk factors, and age-based variation of missed opportunities to diagnose pertussis: A population-based cohort study.

OBJECTIVE: To estimate the incidence, duration and risk factors for diagnostic delays associated with pertussis. DESIGN: We used longitudinal retrospective insurance claims from the Marketscan Commercial Claims and Encounters, Medicare Supplemental (2001-2020), and Multi-State Medicaid (2014-2018) databases. SETTING: Inpatient, emergency department, and outpatient visits. PATIENTS: The study included patients diagnosed with pertussis (International Classification of Diseases [ICD] codes) and receipt of macrolide antibiotic treatment. METHODS: We estimated the number of visits with pertussis-related symptoms before diagnosis beyond that expected in the absence of diagnostic delays. Using a bootstrapping approach, we estimated the number of visits representing a delay, the number of missed diagnostic opportunities per patient, and the duration of delays. Results were stratified by age groups. We also used a logistic regression model to evaluate potential factors associated with delay. RESULTS: We identified 20,828 patients meeting inclusion criteria. On average, patients had almost 2 missed opportunities prior to diagnosis, and delay duration was 12 days. Across age groups, the percentage of patients experiencing a delay ranged from 29.7% to 37.6%. The duration of delays increased considerably with age from an average of 5.6 days for patients aged <2 years to 13.8 days for patients aged ≥18 years. Factors associated with increased risk of delays included emergency department visits, telehealth visits, and recent prescriptions for antibiotics not effective against pertussis. CONCLUSIONS: Diagnostic delays for pertussis are frequent. More work is needed to decrease diagnostic delays, especially among adults. Earlier case identification may play an important role in the response to outbreaks by facilitating treatment, isolation, and improved contact tracing.

Health and Economic Evaluation of Vaccination Against Pertussis in China: A 40-Year Analysis.

OBJECTIVES: This study aimed to evaluate the health and economic impact of diphtheria, tetanus, whole-cell pertussis vaccine (DTwP) and diphtheria-tetanus-acellular pertussis vaccine (DTaP) vaccination on pertussis prevention and control in China during the 40 years from 1978 to 2017. METHODS: We conducted cost-benefit analyses with a decision tree model populated with historical vaccination coverage levels and pertussis incidence and mortality data from before 1978 and during 1978 to 2017. We modeled 40 birth cohorts from birth until death. Costs and benefits were estimated from direct cost and societal perspectives (direct and indirect costs). Costs and benefits were adjusted to 2017 US dollars (USD), and future values were discounted at a 3% annual rate. We calculated net benefit values (net savings) and benefit-cost ratios of pertussis vaccination of children younger than 5 years. We conducted sensitivity analyses by varying key parameters within plausible ranges. RESULTS: Without DTwP and DTaP vaccination, there would be an estimated 115.76 million pertussis cases and 426 650 pertussis deaths in the 40 cohorts. With DTwP/DTaP vaccination, pertussis cases and deaths were decreased by an estimated 92.57% and 97.43%, saving 46 987.81 million USD in direct costs and 82 013.37 million USD from societal perspective. Pertussis vaccination program costs were 2168.76 million USD and 3961.28 million USD from direct cost and societal perspectives. Benefit-cost ratios were 21.67:1 from the direct cost perspective and 20.70:1 from the societal perspective. Sensitivity analyses showed the results to be robust. CONCLUSIONS: Over the lifetime of 40 birth cohorts, China's immunization program is preventing 93% of pertussis cases and 97% of pertussis deaths, resulting in substantial savings to the healthcare system and society.

Cost-Utility Analysis of Universal Maternal Pertussis Immunisation in Thailand: A Comparison of Two Model Structures.

OBJECTIVES: This study aimed to assess the cost-effectiveness of introducing universal maternal pertussis immunisation under the national vaccine programme in Thailand. METHODS: We conducted a cost-utility analysis from a societal perspective to compare maternal vaccination with (1) TdaP vaccine, (2) Td vaccine and aP vaccine, and (3) Td vaccine only. We constructed two decision-tree models with Markov elements, each following a different clinical pathway, to allow us to examine structural uncertainty. Costs were converted to 2021 Thai Baht (THB) and a discount rate of 3% was applied to health and cost outcomes, with sensitivity analysis at 0% and 6%. Parameter uncertainty was investigated through deterministic and probabilistic sensitivity analysis, with expected value of perfect information analysis. RESULTS: Maternal pertussis vaccination would avert 27 cases and up to one death per year. The incremental cost-effectiveness ratio (ICER) for adding aP to the maternal immunisation schedule is 2,184,025 THB/QALY and the ICER for replacing maternal Td vaccination with TdaP is 3,198,101 THB/QALY. Maternal pertussis vaccination only becomes favourable in the probabilistic sensitivity analysis at cost-effectiveness thresholds above 6,000,000 THB/QALY, far above the Thai threshold of 160,000 THB/QALY. If incidence is less than 397 cases per 100,000, maternal pertussis vaccination will not be cost-effective in Thailand, within the plausible range for vaccine effectiveness and probability of hospitalisation. Budget impact is dominated by vaccination costs, which represent 12% and 18% of the 2021 national vaccine programme budget for introducing aP vaccine or for switching Td with TdaP vaccine, respectively. CONCLUSIONS: We have found that maternal pertussis immunisation is not cost-effective in Thailand. Although there may be substantial under-reporting of pertussis cases, comparison with hospital data suggests that most under-reported cases are not hospitalised and therefore have negligible impact on our results. However, considerations such as affordability and local manufacturing may also be important for national immunisation programme decision-making.

Cost-effectiveness of pertussis booster vaccination for preschool children in Japan.

INTRODUCTION: Japan currently recommends four doses of the diphtheria-tetanus-acellular pertussis (DTaP) vaccine in its routine vaccination program, but the introduction of a fifth dose is currently under consideration. An objective of the booster vaccination is to prevent severe cases of pertussis in infants through herd immunity. Thus, the aim of this analysis was to demonstrate the cost-effectiveness of a fifth-dose of the DTaP vaccine for 6-year-old children, taking herd immunity for unvaccinated infants into account. METHOD: An economic model analysis was conducted comparing the cost and effectiveness of the two strategies based on quality-adjusted life years (QALYs). We evaluated the incremental cost-effectiveness ratio (ICER) of the booster strategy to the no booster strategy. This model contained two sub-models: one for children aged 6 years or older and one for infants under 3 months old. Herd immunity for infants is modeled as when siblings in the same family are infected. RESULTS: The ICER was JPY 71,605,491 (USD 656,931) per QALY gained from the societal perspective, and 7.10% of incremental QALYs (0.0000934) were from a reduction in infant infection. In the sensitivity analysis, no variables moved the ICER under the threshold (JPY 5,000,000 per QALY gained), and the duration of pertussis disease and the incidence rate of pertussis had a significant impact on the ICER. When the disease burden of pertussis decreased, the booster strategy resulted in fewer QALYs gained and greater costs compared with the no booster strategy. CONCLUSION: The introduction of a DTaP booster vaccination to the routine immunization schedule can be expected to reduce the number of pertussis cases in the target population. However, our study showed that adding a booster vaccination for 6-year-old children to the schedule in Japan would not be cost-effective in terms of achieving herd immunity among unvaccinated infants.

The impact of pertussis vaccine programme changes on pertussis disease burden in Manitoba, 1992-2017-an age-period-cohort analysis.

BACKGROUND: Changes to pertussis vaccination programmes can have impacts on disease burden that should be estimated independently from factors such as age- and period-related trends. We used age-period-cohort (APC) models to explore pertussis incidence in Manitoba over a 25-year period (1992-2017). METHODS: We identified all laboratory-confirmed cases of pertussis from Manitoba's Communicable Diseases Database and calculated age-standardized incidence rates. We used APC models to investigate trends in pertussis incidence. RESULTS: During the study period, 2479 cases were reported. Age-standardized rates were highest during a large outbreak in 1994 (55 cases/100 000 person-years), with much lower peaks in 1998, 2012 and 2016. We saw strong age and cohort effects in the APC models, with a steady decrease in incidence with increasing age and increased risk in the cohort born between 1980 and 1995. CONCLUSIONS: The highest risk for pertussis was consistently in young children, regardless of birth cohort or time period. The 1981 programme change to an adsorbed whole-cell pertussis vaccine with low effectiveness resulted in reduced protection in the 1981-95 birth cohort and contributed to the largest outbreak of disease during the 25-year study period.

The need for pertussis vaccination among older adults and high-risk groups: a perspective from advanced economies of the Asia Pacific region.

Introduction: Influenza and pneumococcal vaccines are the most regularly prescribed vaccines amongst adults <65 years of age. Pertussis booster vaccines (available as combined diphtheria-tetanus-acellular pertussis, Tdap) uptake is relatively low in many countries in the Asia-Pacific region. Increasing Tdap vaccination is a strategy that may aid healthy aging.Areas Covered: Epidemiology data, including notification reports from 6 advanced economies in Asia (Australia, Hong Kong, New Zealand, Singapore, South Korea, and Taiwan) were reviewed to assess the pertussis disease burden and identify high-risk groups. Existing Tdap vaccination recommendations were reviewed. Current vaccination practices were discussed to benchmark and identify barriers and success factors for Tdap booster vaccination in older adults.Expert Opinion: The available evidence supports Tdap vaccination at an individual level for the prevention of pertussis, along with tetanus and diphtheria in those aged 65+ years, together with influenza and pneumococcal vaccination. Data gaps need to be filled to support the development of national/supranational recommendations for pertussis booster vaccination. Groups at higher risk of pertussis infection and its complications, including those with chronic obstructive pulmonary disease and asthma, could be considered as priority groups. Increasing disease awareness and establishing adult vaccination registries could improve vaccine coverage and promote healthy aging.

PLAIN LANGUAGE SUMMARYPertussis, also called whooping cough, is a common disease in adults. However, how it affects adults in some countries in the Asia-Pacific region is not well understood. In 2019, a panel of experts met to review the available information on adult cases of pertussis in Australia, Hong Kong, New Zealand, Singapore, South Korea, and Taiwan. Here, we present the outcomes of the meeting. Pertussis is increasingly reported in the Asia-Pacific region, including cases diagnosed in adults. The diagnosis may be missed in countries where awareness is still low and/or it is not tested routinely. The experts concluded that physicians should consider recommending pertussis vaccination to older adults (aged 65 or older) on an individual basis, as well as people with asthma or chronic obstructive pulmonary disease, who appear to be at higher risk of severe pertussis. Uptake of pertussis vaccination in adults could be improved by increasing awareness of the vaccines available and vaccination infrastructure for this age-group. Some of the measures proposed were as follows: improved access to vaccination; personalized reminders when vaccines are due; and more education about pertussis in adults for doctors, nursesnurses, and patients. The experts also proposed setting up adult vaccination registries for tracking and evaluation of vaccine uptake. This expert opinion might help the healthcare community build action plans to recognise the burden of the disease and increase rates of vaccination among adults. In addition, better data on the disease burden would help to generate awareness.

Evaluating the impact of a continued maternal pertussis immunisation programme in England: A modelling study and cost-effectiveness analysis.

INTRODUCTION: An unexpected resurgence of pertussis cases and infant deaths was observed in some countries that had switched to acellular pertussis vaccines in the primary immunisation schedule. In response to the outbreaks, maternal pertussis vaccination programmes in pregnant women have been adopted worldwide, including the USA in 2011 and the UK in 2012. Following the success of the programme in England, we evaluated the health and economic impact of stopping versus continuing the maternal pertussis immunisation to inform public health policy making. METHODS: We used a mathematical model to estimate the number of infant hospitalisations and deaths related to pertussis in England over 2019-2038. Losses in quality-adjusted life years, QALYs, were considered for infants (aged 0-2 months) who survived or died from pertussis, bereaved parents (of infants who died from pertussis), and women with pertussis (aged 20-44 years). Direct medical costs to the National Health Service included infant hospitalisations, maternal vaccinations, and disease in women. Costs and QALYs were discounted at 3.5%. Changes in the incremental cost-effectiveness ratio, ICER, were explored in sensitivity analyses. RESULTS: The model supports continuing the maternal pertussis immunisation programme as a cost-effective intervention at an ICER of £14,500/QALY (2.5% and 97.5%-quantile: £7,300/QALY to £32,400/QALY). Stopping versus continuing the maternal programme results in an estimated mean of 972 (range 582 to 1489) versus 308 (184 to 471) infant hospitalisations annually. Results were most sensitive to the number of hospitalisations and deaths when stopping the maternal programme. At a cost-effectiveness threshold of £30,000/QALY, the probability of the maternal programme being cost-effective was 96.2%. CONCLUSION: Our findings support continuing the maternal pertussis vaccination programme as otherwise higher levels of disease activity and infant mortality are expected to return. These results have led policy makers to decide to continue the maternal programme in the UK routine immunisation schedule.

Burden of Pertussis in COPD: A Retrospective Database Study in England.

Chronic obstructive pulmonary disease (COPD) may increase the risk and severity of pertussis infection. Health care resource utilization (HCRU) and direct medical costs (DMC) of treating pertussis among patients with COPD are unknown. Reported incidence of pertussis among individuals aged ≥ 50 years with COPD was assessed in Clinical Practice Research Datalink and Hospital Episode Statistics databases during 2009-2018 using a retrospective cohort design. HCRU and DMC from the National Health Service perspective were compared between patients with COPD and pertussis and propensity score-matched patients with COPD without pertussis. Seventy-eight new pertussis events were identified among 387 086 patients with COPD aged ≥ 50 years (incidence rate: 4.73; 95% confidence interval 3.74-5.91 per 100 000 person-years). HCRU and DMC were assessed among 67 patients with COPD and pertussis and 267 matched controls. During the month before the pertussis diagnosis, the rates of general practitioner (GP)/nurse visits (4289 vs. 1774 per 100 patient-years) and accident and emergency visits (182 vs. 18 per 100 patient-years) were higher in the pertussis cohort; GP/nurse visits (2935 vs. 1705 per 100 patient-years) were also higher during the following 2 months (all p < 0.001). During the month before the pertussis diagnosis, annualized per-patient total DMC were £2012 higher in the pertussis cohort (£3729 vs. £1717; p < 0.001); during the following 2 months, they were £2407 higher (£5498 vs. £3091; p < 0.001). In conclusion, a pertussis episode among individuals with COPD resulted in significant increases in HCRU and DMC around the pertussis event.

Pertussis infant morbidity and mortality trends after universal maternal immunisation in Mexico: An ecological database study with time-series analysis.

INTRODUCTION: Pertussis is a highly contagious infectious disease caused by Bordetella pertussis and a leading cause of infant mortality in Mexico. The Tetanus-diphtheria-acellular pertussis (Tdap) vaccine was recommended in the Mexican Immunisation Programme for pregnant women in 2013. We describe pertussis morbidity and mortality trends in infants ≤2 and ≤12 months of age), before and after maternal Tdap immunisation implementation in Mexico. METHODS: An ecological retrospective database study was performed in the Mexican National and Workers Social Security Institutes (IMSS; ISSSTE). Data were collected on confirmed pertussis ambulatory cases, hospitalisations, and deaths, plus vaccination coverage (Tdap; Diphtheria-tetanus-acellular pertussis [DTPa]) and population estimates. Descriptive and regression time-trend analyses were performed for pertussis morbidity and mortality in infants between pre- (2010-2012) and post- (2014-2018) maternal Tdap immunisation periods. RESULTS: Around 1 million infants a year are covered in IMSS/ISSSTE databases. Average full primary infant DTPa vaccine coverage was 71.4%-72.7% nationally. Since 2013, annual maternal Tdap vaccine coverage ranged from 70%-93%. Between 2010-2018, 2,024 pertussis cases, 2,518 hospitalisations and 71 deaths were reported in infants. Among infants 0-2 months old (maternal immunisation target group), there was a significant decrease, post-maternal vaccination, in pertussis incidence (49.9%, p < 0.000), hospitalisation (70.0%, p < 0.000) and mortality (82.4%, p = 0.003). In infants 0-12 months old, pertussis hospitalisations (28.9%, p = 0.000) and mortality (36.2%, p = 0.059) decreased, but incidence increased (61.8%, p = 0.000). CONCLUSION: After maternal immunisation was implemented, there was a decreasing trend in incidence, hospitalisation and death due to pertussis in infants 0-2 months old. Increases in incidence reported in 0-12-month-olds are likely due to major changes in diagnosis and reporting introduced during the study period as well as limited vaccination and health coverage in some states. These findings confirm the important contribution of the Tdap maternal immunisation programme in reducing pertussis disease burden, particularly severe disease, among infants in Mexico.

Timeliness of immunisation with the pentavalent vaccine at different levels of the health care system in the Lao People's Democratic Republic: A cross-sectional study.

BACKGROUND: The timely administration of vaccines is considered to be important for both individual and herd immunity. In this study, we investigated the timeliness of the diphtheria-tetanus-whole cell pertussis-hepatitis B-Haemophilus influenzae type b (pentavalent) vaccine, scheduled at 6, 10 and 14 weeks of age in the Lao People's Democratic Republic. We also investigated factors associated with delayed immunization. METHODS: 1162 children aged 8-28 months who had received the full course of the pentavalent vaccine at different levels of the health care system were enrolled. Vaccination dates documented in hospital records and/or immunisation cards were recorded. Age at vaccination and time intervals between doses were calculated. Predictors for timely completion with the pentavalent vaccine at 24 weeks were assessed by bivariate and multivariable analyses. RESULTS: Several discrepancies in dates between vaccination documents were observed. In general, vaccination with the pentavalent vaccine was found to be delayed, especially in health care settings below the provincial hospital level. Compared to the central hospital level, less participants who were vaccinated at the district/health center level received the third dose by 16 (48% at the central hospital level vs. 7.1% at the district and 12.4% at the health center level) and 24 weeks of age (94.4% at the central hospital level vs 64.6% at the district-outreach and 57.4% at the health center level) respectively. In logistic regression analyses, lower education level of the mother as well as vaccination by outreach service, were independently associated with delayed completion of vaccination. CONCLUSION: We observed a general delay of vaccination, especially at lower ranked facilities, which correlated with indicators of poor access to health services. This highlights the need for further improving health equity in rural areas. Age-appropriate vaccination should become a quality indicator for the national immunization programme. In addition, we recommend further training of the health care staff regarding the importance of reliable documentation of dates.

A systematic review of the burden of pertussis disease in infants and the effectiveness of maternal immunization against pertussis.

Introduction Infants too young to be fully immunized are the most vulnerable to severe pertussis disease. To close this susceptibility gap, passive infant immunization through vaccination of pregnant women against pertussis was first introduced in 2011 in the United States and has been extended since then to more than 40 countries. Areas covered We conducted two systematic literature searches to describe the worldwide burden of pertussis disease in infants <6 months of age since 2005, and the effectiveness and impact of maternal pertussis vaccination in preventing infant pertussis since 2011. Expert opinion Pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Virtually all pertussis deaths occurred in this age group. Data from Africa, Eastern Mediterranean, and Asia were limited, but suggest a similar or higher disease burden than in Europe or the Americas. Estimates of effectiveness of second/third trimester pertussis vaccination in preventing pertussis disease in <2-3 months old infants were consistently high (69%-93%) across the observational studies reviewed, conducted in various settings with different designs. Maternal vaccination programs appear to be achieving their goal of reducing the burden of disease in very young infants. Plain language summary What is the context? Pertussis, also known as whooping cough, is a highly contagious disease of the respiratory tract. Infants too young to be fully vaccinated are at the highest risk of severe pertussis disease, hospitalization, and death. Vaccinating pregnant women against pertussis with a Tdap vaccine is recommended in more than 40 countries as a safe and effective strategy to protect infants for the first months of life. What is new? This review summarizes recent literature describing the burden of pertussis disease in infants worldwide prior to the introduction of maternal vaccination programs; pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Immunization of pregnant women with a Tdap vaccine can prevent about 70-90% of pertussis disease and up to 90.5% of pertussis hospitalizations in infants under 3 months of age. What is the impact? Limited available data suggest that incidence rates of pertussis disease after the introduction of Tdap maternal immunization have declined in infants. Current knowledge supports the implementation of Tdap maternal immunization programs.