Effectiveness of the trivalent influenza vaccine in Navarre, Spain, 2010-2011: a population-based test-negative case-control study.

BACKGROUND: Some studies have evaluated vaccine effectiveness in preventing outpatient influenza while others have analysed its effectiveness in preventing hospitalizations. This study evaluates the effectiveness of the trivalent influenza vaccine in preventing outpatient illness and hospitalizations from laboratory-confirmed influenza in the 2010-2011 season. METHODS: We conducted a nested case-control study in the population covered by the general practitioner sentinel network for influenza surveillance in Navarre, Spain. Patients with influenza-like illness in hospitals and primary health care were swabbed for influenza testing. Influenza vaccination status and other covariates were obtained from health care databases. Using logistic regression, the vaccination status of laboratory-confirmed influenza cases was compared with that of test-negative controls, adjusting for age, sex, comorbidity, outpatient visits in the previous 12 months, health care setting, time between symptom onset and swabbing, period and A(H1N1)pdm09 vaccination. Effectiveness was calculated as (1-odds ratio)x100. RESULTS: The 303 confirmed influenza cases (88% for A(H1N1)pdm09 influenza) were compared with the 286 influenza test-negative controls. The percentage of persons vaccinated against influenza was 4.3% and 15.7%, respectively (p<0.001). The adjusted estimate of effectiveness was 67% (95% CI: 24%, 86%) for all patients and 64% (95% CI: 8%, 86%) in those with an indication for vaccination (persons age 60 or older or with major chronic conditions). Having received both the 2010-2011 seasonal influenza vaccine and the 2009-2010 pandemic influenza vaccine provided 87% protection (95% CI: 30%, 98%) as compared to those not vaccinated. CONCLUSION: The 2010-2011 seasonal influenza vaccine had a moderate protective effect in preventing laboratory-confirmed influenza.

[Effect of the time between symptom onset, swabbing and testing on the detection of influenza virus]. / Influencia de los tiempos entre el inicio de síntomas, la toma de frotis nasofaríngeo y su procesamiento en laboratorio en la detección de gripe.

BACKGROUND: 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). METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Mortality by causes in HIV-infected adults: comparison with the general population.

BACKGROUND: We compared mortality by cause of death in HIV-infected adults in the era of combined antiretroviral therapy with mortality in the general population in the same age and sex groups. METHODS: Mortality by cause of death was analyzed for the period 1999-2006 in the cohort of persons aged 20-59 years diagnosed with HIV infection and residing in Navarre (Spain). This was compared with mortality from the same causes in the general population of the same age and sex using standardized mortality ratios (SMR). RESULTS: There were 210 deaths among 1145 persons diagnosed with HIV (29.5 per 1000 person-years). About 50% of these deaths were from AIDS. Persons diagnosed with HIV infection had exceeded all-cause mortality (SMR 14.0, 95% CI 12.2 to 16.1) and non-AIDS mortality (SMR 6.9, 5.7 to 8.5). The analysis showed excess mortality from hepatic disease (SMR 69.0, 48.1 to 78.6), drug overdose or addiction (SMR 46.0, 29.2 to 69.0), suicide (SMR 9.6, 3.8 to 19.7), cancer (SMR 3.2, 1.8 to 5.1) and cardiovascular disease (SMR 3.1, 1.3 to 6.1). Mortality in HIV-infected intravenous drug users did not change significantly between the periods 1999-2002 and 2003-2006, but it declined by 56% in non-injecting drug users (P = 0.007). CONCLUSIONS: Persons with HIV infection continue to have considerable excess mortality despite the availability of effective antiretroviral treatments. However, excess mortality in the HIV patients has declined since these treatments were introduced, especially in persons without a history of intravenous drug use.

[Resurgence of mumps in the vaccine era. Factors involved in an outbreak in Navarre, Spain, 2006-2007]. / Rebrote de parotiditis en la era vacunal. Factores implicados en un brote en Navarra, 2006-2007.

BACKGROUND AND OBJECTIVE: We analysed a mumps outbreak that occurred in Navarre between August 2006 and December 2007, in which vaccinated persons were widely affected. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Considerations on surveillance of HIV infections. The experience of Navarre (Spain)]. / Consideraciones sobre la cuantificación de las infecciones por el VIH. La experiencia de Navarra.

OBJECTIVE AND METHODS: The number and proportion of cases in the HIV registry of Navarre (Spain) that were residents of this region were quantified, according to the census and the healthcare card database. RESULTS: Of the 2,385 persons diagnosed with HIV infection to 2003, only 1,610 (67.5%) were residents of Navarre. The rate of HIV cases diagnosed among residents in Navarre was over 90 cases per million between 1994 and 1998, with values similar to those of Switzerland. In contrast with the time-trend in other European countries, the time-trend in Navarre decreased from 1994 to 2003. Since 2000 the rate of new HIV cases in Navarre has been lower than rates in Portugal, Switzerland, Luxembourg, Belgium, Ireland, and the United Kingdom. CONCLUSION: To prevent overestimation of the number of HIV infections, cases duplicated between regions should be excluded. This could be achieved by a national HIV surveillance system.

Effectiveness of one and two doses of varicella vaccine in preventing laboratory-confirmed cases in children in Navarre, Spain.

Varicella vaccine effectiveness was evaluated in a case-control study in Navarre, Spain, in 2010-2012. The cases were 54 children aged 15 months to 10 years with a diagnosis of varicella confirmed by polymerase-chain-reaction. Each case was matched with eight controls by pediatric practice, district of residence and date of birth. The effectiveness was 87% (95% confidence interval: 60% to 97%) for one dose of vaccine and 97% (80% to 100%) for two doses. A single dose was 93% (34% to 100%) effective in the first year, which declined to 61% (95% CI: -64% to 94%) after the third year. In conclusion, varicella vaccine is highly effective in preventing confirmed cases, although this effect declines over time since the first dose. A second dose helps to reestablish very high levels of effectiveness and to reduce the risk of breakthrough varicella.

Effectiveness of rotavirus vaccines in preventing cases and hospitalizations due to rotavirus gastroenteritis in Navarre, Spain.

Two rotavirus vaccines have been available since 2006. This study evaluates the effectiveness of these vaccines using a test-negative case-control design in Navarre, Spain. We included children 3-59 months of age who sought medical care for gastroenteritis and for whom stool samples were taken between January 2008 and June 2011. About 9% had received the pentavalent vaccine (RotaTeq) and another 8% received the monovalent vaccine (Rotarix). Cases were the 756 children with confirmed rotavirus and controls were the 6036 children who tested negative for rotavirus. Thirty-five percent of cases and 9% of controls had required hospitalization (p<0.0001). The adjusted effectiveness of complete vaccination was 78% (95% CI: 68-85%) in preventing rotavirus gastroenteritis and 83% (95% CI: 65-93%) in preventing hospitalization for rotavirus gastroenteritis. No differences between the two vaccines were detected (p=0.4523). Both vaccines were highly effective in preventing cases and hospital admissions in children due to rotavirus gastroenteritis.

Vaccine effectiveness in preventing influenza hospitalizations in Navarre, Spain, 2010-2011: cohort and case-control study.

We evaluated the 2010-2011 seasonal influenza vaccine effectiveness in preventing hospitalizations. Using healthcare databases we defined the target population for vaccination in Navarre, Spain, consisting of 217,320 people with major chronic conditions or aged 60 years and older. All hospitalized patients with influenza-like illness (ILI) were swabbed for influenza testing. A total of 269 patients with ILI were hospitalized and 61 of them were found positive for influenza virus: 58 for A(H1N1)2009 and 3 for B virus. The incidence rates of hospitalization with laboratory-confirmed influenza were compared by vaccination status. In the Cox regression model adjusted for sex, age, children in the household, urban/rural residence, comorbidity, pandemic vaccination, pneumococcal vaccination, outpatient visits and hospitalization in the previous year, the seasonal vaccine effectiveness was 58% (95% CI: 16-79%). The nested test-negative case-control analysis gave an adjusted estimate of 59% (95% CI: 4-83%). These results suggest a moderate effect of the 2010-2011 seasonal influenza vaccine in preventing hospitalization in a risk population. The close estimates obtained in the cohort and the test-negative case-control analyses suggest good control of biases.

Effectiveness of the monovalent influenza A(H1N1)2009 vaccine in Navarre, Spain, 2009-2010: cohort and case-control study.

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.

[Differences between summer and fall waves of influenza in the pandemic of influenza (H1N1) 2009 in Navarre, Spain]. / Diferencias entre las ondas gripales de verano y de otoño durante la pandemia de gripe (H1N1) 2009 en Navarra.

BACKGROUND: 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. METHODS: 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). RESULTS: 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). CONCLUSION: Influenza circulation was much lower in the summer. Serious cases occurred in periods of both high and low incidence of influenza syndromes.

Effectiveness of Jeryl Lynn-containing vaccine in Spanish children.

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.

[Trends in mortality and causes of death among persons with HIV infection, 1985-2004]. / Cambios en la mortalidad y en las causas de defunción en las personas con diagnóstico de infección por el VIH, 1985-2004.

OBJECTIVE: To describe the changes in causes of death among persons with HIV infection. METHODS: An analysis of mortality according to cause was performed in persons diagnosed with HIV infection and residing in the province of Navarre (Spain) from 1985 to 2004. RESULTS: Among 1,649 persons diagnosed with HIV infection up to 2004, 709 (43.0%) had died. Mortality reached the maximum in 1993-1996 with 83.1 deaths per 1,000 person-years (PY). Since that time and up to 2001-2004, mortality due to AIDS decreased from 68.3 to 14.1 per 1,000 PY (p = 0.0001). From 1989-1992 period to the 2001-2004 period, mortality due to drug overdose dropped from 9.2 to 3.6 per 1,000 PY (p = 0.0035) and mortality due to hepatic disease rose from 1.6 to 6.6 per 1000 PY (p = 0.0061), with no significant changes in all other causes. In 2001-2004, AIDS continued to be the first cause of death (44.4%) in this population, followed by hepatic disease (20.9%) and drug overdose (11.3%). In the era of potent antiretroviral therapy (1997-2004), death caused by AIDS (rate ratio = 0.63; p = 0.0344) and by all other causes (RR = 0.59; p = 0.0232) was lower among women. In addition, mortality due to causes other than AIDS was higher in persons 40 years of age and older (RR = 1.77; P = 0.0050) and mortality was lower in homosexual men (RR = 0.22; p = 0.0360). A simultaneous diagnosis of HIV infection and AIDS was associated with higher mortality by AIDS (RR, 3.39; p < 0.0001). CONCLUSIONS: AIDS continues to be the primary cause of death in HIV-infected people, and mortality due to hepatic diseases and drug overdose is high. Early diagnosis of HIV-infection would reduce the incidence of deaths due to AIDS.