Assessment of Pertussis Underreporting in Italy

Understanding the impact of adult pertussis and current approaches to vaccination: A narrative review and expert panel recommendations

Pertussis has several notable consequences, causing economic burden, increased strain on healthcare facilities, and reductions in quality of life. Recent years have seen a trend toward an increase in pertussis cases affecting older children and adults. To boost immunity, and protect vulnerable populations, an enduring approach to vaccination has been proposed, but gaps remain in the evidence surrounding adult vaccination that are needed to inform such a policy. Gaps include: the true incidence of pertussis and its complications in adults; regional variations in disease recognition and reporting; and incidence of severe disease, hospitalizations, and deaths in older adults. Better data on the efficacy/effectiveness of pertussis vaccination in adults, duration of protection, and factors leading to poor vaccine uptake are needed. Addressing the critical evidence gaps will help highlight important areas of unmet need and justify the importance of adult pertussis vaccination to healthcare professionals, policymakers, and payers.

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

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

Overview of adult immunization in Italy: Successes, lessons learned and the way forward

The exchange of knowledge and best practices in adult immunization are essential to improve vaccination strategies across the European region. Italy has made groundbreaking progress in the field, being one of the first countries to propose a life-course vaccination schedule, broadening the traditional focus on childhood immunization to include adults. All vaccines included in Italy's vaccination schedule are free of charge. Moreover, the country's National Immunization Plan sets clear coverage targets, immunization priorities, and actions to reduce disparities. However, the fragmentation of its National Health System following the constitutional reform of 2001 has led to an increased complexity and regional inequalities regarding immunization. Other challenges the country faces include growing vaccine hesitancy, data gaps and underserved populations. This review describes Italy's adult immunization system, from policy to implementation. The successes, challenges and lessons learned were shared during the first Adult Immunization Board country meeting in Italy, where local experts, healthcare providers, public health representatives, and policymakers engaged in collaborative discussions and shared insights through case studies and presentations (December 2023). These insights are reviewed and discussed in this manuscript.

Pertussis Notification Rate and Tdpa Vaccine/Booster Coverage in Adults: An Opportunity for an Epidemiological Observatory in Primary Care

Background: In recent years, Europe has experienced a significant increase in pertussis cases. One reason behind this rise is the decline in diphtheria-tetanus-pertussis (dTap) booster coverage among adults. Currently, Italy lacks a reliable monitoring system to track pertussis infections and vaccine coverage among adults. We therefore evaluated the reliability of a primary care framework to respond to this need. Methods: Using an Italian primary care database for individuals aged 15 or above, we determined the pertussis infection notification rate and dTap vaccine/booster coverage for the timeframe of 2009-2022. Results: In the overall population, we obtained a lifetime occurrence rate of pertussis infections of 7.52 per 10,000 individuals. The annual incidence rates of pertussis infections ranged from 0.008 to 0.001 per 10,000 person-years between 2009 and 2022. A rising trend in dTap vaccine coverage rate (ranging from 8.72 to 16.54 vaccines per 10,000 individuals) was observed during the same period. Notably, those aged 65 or older, smokers, and/or individuals with immunodeficiencies were more likely to receive the dTap vaccine compared to the general population. Conclusions: Given the organization of the Italian public health system, this primary care network might act as a reliable epidemiological monitoring system to keep track of pertussis infections and dTap vaccine coverage in adults. Pertussis cases were underreported, and there was a low uptake of vaccines and boosters. Therefore, it is crucial to closely monitor pertussis notifications and dTap administrations and develop intervention strategies at the national level to enhance vaccine-related prevention.

Seroprotection against tetanus in the Italian general population

BACKGROUND

Tetanus is a non-communicable disease, preventable with vaccination. Despite the implemented vaccination strategy, a certain number of tetanus cases per year continue to occur. The aim of the study was to evaluate the seroprevalence of anti-tetanus antibodies in the Italian population by age, sex and geographical area.

METHODS

To determine the level of tetanus-specific antibodies, an immunoenzymatic assay was used.

RESULTS

A total of 3,821 serum samples were collected in the years 2019-20 from healthy subjects aged 6-90 years residing in 13 Italian regions. Overall, 85 % of the tested subjects resulted positive. The rate of subjects protected against tetanus showed a gradual decrease from the younger age groups to the older ones (6-12 years: 93.6 %, 13-24 years: 91.8 %, 25-39 years: 91.0 %, 40-64 years: 78.2 %, ≥ 65 years: 45.3 %); this is particularly evident in the Southern regions and Islands. Moreover, the prevalence of subjects with low protection (<0.1 IU/ml) was significantly higher in the ≥ 65 age group (10.3 %). Males and females' prevalence showed a significant difference only in the oldest age group (M: 60.8 %, F: 30.4 %). In general, a higher prevalence was observed for Northern (90.8 %) and Central regions (87.3 %) than Southern regions and Islands (80.0 %).

CONCLUSION

These data, compared with epidemiological ones which showed a high number of cases in the elderly, confirmed that the population with lower protection has a greater risk of contracting the disease, demonstrating the need for adequate immunization through both primary vaccination and boosters for all ages and both sexes, in order to provide lifelong protection.

Pertussis Epidemiology in the Autonomous Province of Vojvodina, Serbia, 1948-2023

Pertussis continues to be a significant public health concern. We aimed to examine the epidemiological characteristics of pertussis in Vojvodina, which accounts for almost a third of Serbia's population. Our aim was to determine the overall and age-specific incidence and mortality rates of pertussis in Vojvodina from 1948 to 2023, as well as the coverage of immunization against pertussis from 1960 to 2023. In the period 1948-2023, 42,259 cases of pertussis were reported. Following the introduction of the DTwP vaccine (1960) in Serbia, the reported incidence of pertussis began to decline. In 2001, for the first time since introduction of pertussis surveillance in Vojvodina, no pertussis cases were reported. Since 2012, the reported incidence of pertussis has once again increased, and peaked (41.1/100,000) in 2023, approaching the incidence rates recorded shortly after the introduction of DTwP vaccine. A shift in the age profile of pertussis from children aged 0-6 years to school-aged children (7-14 years) occurred between 2012 and 2023, when 48.3% of pertussis cases occurred in this age group. Although the incidence rates of pertussis among individuals aged 20 years and older were significantly lower than among younger age groups, there is evidence of an increasing trend in pertussis cases, particularly among those aged 40-49 years, since 2012. Based on the findings of this study, it is imperative to introduce additional booster doses of the aP vaccine for individuals aged 14 years, along with implementing maternal immunization strategies targeting women of childbearing age.

Assessing the Underestimation of Adult Pertussis Disease in Five Latin American Countries

INTRODUCTION

Pertussis, a contagious respiratory disease, is underreported in adults. The study objective was to quantify underestimation of pertussis cases in adults aged ≥ 50 years in five Latin American countries (Argentina, Brazil, Chile, Mexico, Peru).

METHODS

A previously published probabilistic model was adapted to adjust the number of pertussis cases reported to national surveillance systems by successive multiplication steps (proportion of pertussis cases seeking healthcare; proportion with a specimen collected; proportion sent for confirmatory testing; proportion positive for pertussis; proportion reported to passive surveillance). The proportions at each step were added in a random effects model to produce a pooled overall proportion, and a final multiplier was calculated as the simple inverse of this proportion. This multiplier was applied to the number of cases reported to surveillance to estimate the number of pertussis cases. Monte Carlo simulation with 10,000 iterations estimated median as well as upper and lower 90% values. Input data were obtained from surveillance systems and published sources.

RESULTS

The estimated median underestimation factor for pertussis cases in adults ranged from 104 (90% limits 40, 451) in Chile to 114 (90% limits 39, 419) in Argentina. In all five countries, the largest estimated number of cases was in the group aged 50-59 years. The highest number per 100,000 population was in the group aged ≥ 90 years in most countries. The estimated median underestimation factor for pertussis hospitalizations was 2.3 (90% limits 1.8, 3.3) in Brazil and 2.4 (90% limits 1.8, 3.2) in Chile (data not available for other countries).

CONCLUSION

This analysis indicates that the number of pertussis cases in adults aged ≥ 50 years in five Latin American countries is approximately 100 times higher than the number captured in surveillance data. These results could support decision-making in the diagnosis, management, and prevention of pertussis disease in adults.

Knowledge and attitude factors associated with the prevalence of Tdap (tetanus, diphtheria, and acellular pertussis) booster vaccination in healthcare workers in a large academic hospital in Southern Italy in 2022: a cross-sectional study

Introduction

In Europe, there is still suboptimal tetanus, diphtheria, and acellular pertussis (Tdap) booster coverage. This study aimed to assess coverage status, knowledge, and attitude on Tdap vaccination in healthcare workers (HcWs) of the University Hospital "Federico II" in Naples, Southern Italy, in 2022, to improve current vaccination strategies.

Methods

A cross-sectional study was conducted using a validated anonymous questionnaire. Knowledge and attitude were measured as scores. Multivariable logistic and linear regression models were employed to identify correlates of Tdap booster and knowledge and attitude toward the vaccination, as appropriate. Models were controlled for age, sex, profession, department, and job seniority.

Results

A total of 206 questionnaires were administered among HcWs, and 143 (69.4%) were medical doctors. In total, 71 (34.47%) HcWs received the Tdap booster. Those who have worked 5-9 years at the hospital had a 78% lower likelihood of being vaccinated with the Tdap booster (5-9 years-OR: 0.22, CI: 0.06 | 0.85) as compared with newly hired HcWs. No differences in the average knowledge score were found. Other healthcare workers had a lower attitude as compared to medical doctors (Other-Coef. -2.15; CI: -4.14 | -0.15) and, as compared with those who worked in a clinical department, those who worked in a diagnostic-therapeutic department or medical management had 3.1 and 2.0 lower attitude scores, on average, respectively (diagnostic-therapeutic-Coef. -3.12, CI: -5.13 | -1.12; public health-Coef. -1.98, CI: -3.41 | -0.56).

Discussion

The study findings support the necessity to implement public health strategies and improve knowledge and attitude toward vaccinations and specifically highlight the importance of Tdap booster every 10 years as a prevention tool to protect high-risk populations.