Trends in Hospital Admissions for Pertussis Infection: A Nationwide Retrospective Observational Study in Italy, 2002–2016

Abstract

Background: Pertussis is a highly contagious infectious disease which continues to be an important public-health issue despite the high immunization coverage rates achieved. However, evidence of increased circulation of pertussis among adolescents and adults due to waning immunity and atypical clinical manifestations seem to be the main reasons for its resurgence. The aim of this study was the analysis of the epidemiological trend for pertussis-related hospitalizations in Italy, in relation with vaccination coverage and information from laboratory confirmed cases of pertussis. Methods: A retrospective observational study investigating hospitalizations for pertussis from 2002 to 2016 in Italy was conducted. Frequencies and rates of hospitalization were analyzed and hospitalization data were compared with a series of already published laboratory confirmed data. Results: This study highlighted a rising trend for pertussis hospitalizations in Italy since 2008. Infants aged <1 year showed the highest frequencies (63.39%) and average rates (74.60 × 100000 infants) of hospitalization despite an extremely high vaccination coverage (95.89%). An increasing trend of hospitalization frequency emerged for the age group with levels of IgG antibodies to pertussis toxin compatible with pertussis infection within the last year (20–29 years old age group). Conclusions: The rising trend for pertussis hospitalizations and the greater involvement of infants aged <1 year require an integrated approach, including the implementation of booster doses administration in adolescence and adulthood, the vaccination of pregnant women and the cocoon strategy.

Pertussis in Italy: how to protect the “unprotectable”?

“…3 The percentage of cases bearing the code 033.9, related to pertussis due to unspecified pathogens, was 48.6% indicating that more efforts should be made to implement the etiological diagnosis in order to reduce the under-notification of the disease, whereas in Italy pertussis notification is made on a clinical diagnosis. 8,11 Pertussis epidemiology is changing in Italy, with a lower incidence in children and an increased incidence in adolescents and adults: comparing period with a low (1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989), intermediate (1990)(1991)(1992)(1993)(1994)(1995)(1996) and high (1998-2002) vaccination coverage, the percent distribution of cases has appeared markedly changed, declining by half in the 0-4 y age group, while increasing by 1.5-fold in the 5-9 y age group and three-fold in the 10-14 y age group. 13 Thus, adolescents and adults represent a significant source of infection for unvaccinated or incompletely immunized newborns/infants in whom the severity of the disease can be serious.…”

“…The percentage of cases bearing the code 033.9, related to pertussis due to unspecified pathogens, was 48.6% indicating that more efforts should be made to implement the etiological diagnosis in order to reduce the under-notification of the disease, whereas in Italy pertussis notification is made on a clinical diagnosis. 8 , 11 …”

“…7 Despite a high vaccination coverage, a retrospective study reviewing the Italian national hospital discharge form database showed that, in the period 2002-2016, most hospitalizations (63.39%) involved subjects <1 y of age. 8 As infant-specific pertussis epidemiologic data, especially among neonates, in Italy were limited, the present study was designed to address this knowledge gap.…”

“…7 Despite a high vaccination coverage, a retrospective study reviewing the Italian national hospital discharge form database showed that, in the period 2002–2016, most hospitalizations (63.39%) involved subjects <1 y of age. 8 …”

Descriptive Observational Study of Tdap Vaccination Adhesion in Pregnant Women in the Florentine Area (Tuscany, Italy) in 2019 and 2020

“…Moreover, Germany, the Netherlands, Norway, Spain and the United Kingdom altogether accounted for 72% of all notified cases in all age groups. In Italy, it has been reported a rising trend of pertussis hospitalizations in the period 2002–2016, and infants <1-year-old showed the highest percentage (63.4%) and average hospitalization rates (74.6/100,000) [ 7 ]. During the period 2010–2019, pertussis vaccination coverage (VC) rates in the Tuscany region were reported as >95% (except for the year 2016); nevertheless, 38 cases of pertussis were notified in Tuscany in 2019, and 11 of these were hospitalized [ 8 ].…”