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ABSTRACT: Influenza surveillance requires the collection of nasopharyngeal swabs in Primary Care for testing in reference laboratories. We evaluated the influence on the laboratory results of the time since the onset of symptoms to swabbing (TSS) and from then until laboratory processing (TSL).
We analysed swabs collected in the Sentinel Network of Navarra during the 2009-2010 influenza season. The samples were kept refrigerated until analysed by RT-PCR and viral culture. We analysed the percentage of positive swabs to influenza virus in accordance with the TSS and TSL by logistic regression.
From a total of 937 swabs, 373 (40%) were positive for influenza by RT-PCR. The TSS ranged from 0-15 days. In the adjusted analysis by period, laboratory and age, having a positive influenza culture decreased to less than half when the TSS was 4-5 days (OR=0.47; 95% CI, 0.24-0.94), and having a positive RT-PCR decreased when the TSS was 5 days or more (OR=0.24, 95% CI, 0.09-0.65). TSL does not significantly affect the result of the RT-PCR (OR by each day=0.96; 95% CI, 0.88-1.04), or the result of the viral culture (OR by each day=0.97, 95% CI, 0.89-1.06).
A TSS over 3 days reduced the likelihood of confirmation of influenza, affecting the viral culture more than the RT-PCR. A TSL within a range of two weeks had no significant effect on the results of the RT-PCR or the viral culture.
Enfermedades Infecciosas y Microbiología Clínica 09/2011; 30(1):11-4. · 1.49 Impact Factor
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Jesús Castilla,
Julio Morán,
Víctor Martínez-Artola, Mirian Fernández-Alonso,
Marcela Guevara,
Manuel García Cenoz,
Gabriel Reina,
Nerea Alvarez,
Maite Arriazu,
Fernando Elía,
Esther Salcedo,
Aurelio Barricarte
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ABSTRACT: We defined a population-based cohort (596,755 subjects) in Navarre, Spain, using electronic records from physicians, to evaluate the effectiveness of the monovalent A(H1N1)2009 vaccine in preventing influenza in the 2009-2010 pandemic season. During the 9-week period of vaccine availability and circulation of the A(H1N1)2009 virus, 4608 cases of medically attended influenza-like illness (MA-ILI) were registered (46 per 1000 person-years). After adjustment for sociodemographic covariables, outpatient visits and major chronic conditions, vaccination was associated with a 32% (95% CI: 8-50%) reduction in the overall incidence of MA-ILI. In a test negative case-control analysis nested in the cohort, swabs from 633 patients were included, and 123 were confirmed for A(H1N1)2009 influenza. No confirmed case had received A(H1N1)2009 vaccine versus 9.6% of controls (p<0.001). The vaccine effectiveness in preventing laboratory-confirmed influenza was 89% (95% CI: 36-100%) after adjusting for age, health care setting, major chronic conditions and period. Pandemic vaccine was effective in preventing MA-ILI and confirmed cases of influenza A(H1N1)2009 in the 2009-2010 season.
Vaccine 06/2011; 29(35):5919-24. · 3.77 Impact Factor
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ABSTRACT: Two waves of influenza (H1N1) 2009 were produced in Navarre in 2009, one in the summer and the other in the fall. We aim to compare the characteristics of the two epidemic waves.
We analysed individual influenza reports, virological confirmations in the primary care sentinel network, and hospitalised cases with confirmed influenza in Navarre. We compared the summer period (week 21 to 39 in 2009) with the fall-winter period (week 40 in 2009 to 20 in 2010).
Two waves of influenza A(H1N1)2009 occurred during 2009, with peaks in July and November. In the summer (week 21 to 39) 4389 cases of influenza syndrome were reported, with young adults the most affected group (58% aged 15-44 years). The highest incidence was registered after the San Fermin fiesta (92 cases per 100,000 population in week 29), with immediate return to baseline levels. A second wave occurred in the fall, with rates up to 7 times higher (667 cases per 100,000 in week 45); they remained above the epidemic threshold for 9 weeks, with children aged 5-14 years (111 per 1000) the most affected group. In the peak of both waves the percentage of smears confirmed for influenza reached 60%. During the summer there were 66 admissions with confirmed influenza (H1N1) 2009, and 158 than in the fall. The proportion of cases requiring admission to hospital was higher in the summer (1.5%) than in fall (0.8%: p<0,0001).
Influenza circulation was much lower in the summer. Serious cases occurred in periods of both high and low incidence of influenza syndromes.
Revista Española de Salud Pública 02/2011; 85(1):47-56. · 0.71 Impact Factor
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ABSTRACT: We analysed a mumps outbreak that occurred in Navarre between August 2006 and December 2007, in which vaccinated persons were widely affected.
Reports of mumps cases were completed by searching primary, emergency and hospital records and laboratory reports. Factors that could affect the occurrence of cases were analysed by birth cohort.
A total of 2866 mumps cases were detected (attack rate 4.7/1000), with 61% of cases in men and a peak incidence at age 19 (inter-quartile range 16-25 years). 14% of cases were confirmed by laboratory: 59 by virus isolation, 14 by PCR and 333 by IgM. The G1 genotype was identified in 7 cases. 21% of cases had been born before 1980 (pre-vaccine cohorts), and 0.2% had not yet reached the vaccination age (15 months). In the cohorts born between 1980 and 2000 (with the opportunity for vaccination), 94.5% of cases had received at least one dose and 88.3%, two doses. 31% of cases occurred in cohorts vaccinated with a first (1995-1997) or second (1986-1988) dose of the Rubini strain. There was also a record of 772 cases who had received two doses of the Jeryl Lynn strain.
This widespread outbreak is explained by the concurrence of various factors. The current vaccine has substantially reduced the incidence of mumps, but appears unable to totally eliminate virus circulation.
Medicina Clínica 10/2009; 133(20):777-82. · 1.38 Impact Factor
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Medicina Clínica 04/2009; 134(8):377-8. · 1.38 Impact Factor
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ABSTRACT: We evaluated the effectiveness of the Jeryl Lynn strain vaccine in a large outbreak of mumps in Navarre, Spain, 2006-2008. Each of the 241 cases of mumps occurring in children over 15 months of age born between 1998 and 2005 was compared with 5 controls individually matched by sex, birth date, district of residence and paediatrician. Vaccination history was obtained blindly from clinical records. Conditional logistic regression was used to obtain the matched odds ratios (ORs), and effectiveness was calculated as 1-OR. Some 70% of cases had received one dose of measles-mumps-rubella vaccine, and 24% had received two doses. Overall vaccine effectiveness was 72% (95% CI, 39-87%). Two doses were more effective (83%; 54-94%) than a single dose (66%; 25-85%). Among vaccinated children, risk was higher in those who had received the first dose after 36 months of age (OR=3.1; 1.2-8.4) and those who had received the second dose 3 or more years before study enrolment (OR=10.2; 1.5-70.7). Early waning of immunity in children after the second dose may contribute to reduced vaccine effectiveness for mumps prevention.
Vaccine 04/2009; 27(15):2089-93. · 3.77 Impact Factor
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Jesús Castilla,
Julio Morán,
Víctor Martínez-Artola, Mirian Fernández-Alonso,
Marcela Guevara,
Manuel García Cenoz,
Gabriel Reina,
Nerea Alvarez,
Maite Arriazu,
Fernando Elía,
Esther Salcedo,
Aurelio Barricarte
[show abstract]
[hide abstract]
ABSTRACT: We defined a population-based cohort (596,755 subjects) in Navarre, Spain, using electronic records from physicians, to evaluate the effectiveness of the monovalent A(H1N1)2009 vaccine in preventing influenza in the 2009–2010 pandemic season. During the 9-week period of vaccine availability and circulation of the A(H1N1)2009 virus, 4608 cases of medically attended influenza-like illness (MA-ILI) were registered (46 per 1000 person-years). After adjustment for sociodemographic covariables, outpatient visits and major chronic conditions, vaccination was associated with a 32% (95% CI: 8–50%) reduction in the overall incidence of MA-ILI. In a test negative case–control analysis nested in the cohort, swabs from 633 patients were included, and 123 were confirmed for A(H1N1)2009 influenza. No confirmed case had received A(H1N1)2009 vaccine versus 9.6% of controls (p < 0.001). The vaccine effectiveness in preventing laboratory-confirmed influenza was 89% (95% CI: 36–100%) after adjusting for age, health care setting, major chronic conditions and period. Pandemic vaccine was effective in preventing MA-ILI and confirmed cases of influenza A(H1N1)2009 in the 2009–2010 season.
Vaccine. 29(35):5919-5924.
