title: Increase of pertussis incidence in 2010 to 2012 after 12 years of low circulation in Spain.
abstract: In Spain, whole cell pertussis vaccination started in 1975, with three doses before the age of 6-7 months. Doses at 15-18 months and 4-6 years were introduced in 1996 and 2001, respectively. Spain switched to an acellular vaccine in 2005. From 1998 to 2009, pertussis incidence rates remained ≤1.5 cases/100,000 inhabitants but increased from 2010 to 7.5 cases/100,000 in 2012. Data from 1998 to 2012 were analysed to assess disease trends and susceptible populations. We defined four epidemic periods: 1998-2001 (reference), 2002-05, 2006-09 and 2010-12. In 2002-05, the incidence rate increased in individuals aged 15-49 years (IRR: 1.41 (95% CI: 1.11-1.78)) and ≥50 years (IRR: 2.78 (95% CI: 1.78-4.33)) and in 2006-09 increased also in infants aged <3 months (IRR: 1.83 (95% CI: 1.60-2.09)). In 2010-12, the incidence rate increased notably in all age groups, with IRRs ranging between 2.5 (95% CI: 2.3-2.8) in 5-9 year-olds and 36.0 (95% CI: 19.4-66.8) in 20-29 year-olds. These results, consistent with the country's vaccination history, suggest a progressive accumulation of susceptible individuals due to waning immunity after years of low incidence. Further vaccination strategies should be assessed and implemented to prevent pertussis in pre-vaccinated infants, in whom the disease is more severe.
authors.affiliation: National Centre for Epidemiology, Institute of Health Carlos III, Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Sizaire
authors.forename: M
authors.initials: M
authors.lastname: Garrido-Estepa
authors.forename: J
authors.initials: J
authors.lastname: Masa-Calles
authors.forename: M V
authors.initials: MV
authors.lastname: Martinez de Aragon
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001886:Bordetella pertussis / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D058872:Epidemics; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D017589:Immunization Programs; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D011159:Population Surveillance; D013030:Spain / Q000453:epidemiology; D013997:Time Factors; D014917:Whooping Cough / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D055815:Young Adult
chemical_list: D010567:Pertussis Vaccine