Absence of short-term changes in knowledge and attitudes among household contacts of COVID-19 cases during the post-acute phase of the pandemic in Catalonia and Navarre, Spain.

Objectives: To evaluate short-term changes in knowledge and attitude towards COVID-19 and preventive measures during the post-acute phase of the pandemic in Spain. Methods: A survey was performed in Catalonia and Navarre between May-2022 and July-2023 in household contacts of COVID-19 cases. Knowledge and attitude were assessed at baseline and at three months, using a Likert scale. Responses were grouped according to correct or incorrect. Results: At baseline, 172 subjects were contacted, 118 (69%) of which completed a follow-up interview three months later. Knowledge of correct hand-washing and mask protocols had maintained over time (-1.7%, p = 0.553 and - 2.5%, p = 0.473, respectively). Attitudes toward preventive measures was adequate in the first interview (86%), but attitudes regarding use of face masks decreased significantly (-9.1%, p = 0.048) over time in participants with higher risk of severe COVID-19. However, most short-term changes in knowledge and attitudes were not statistically significant. Conclusion: Household contacts showed correct knowledge and attitude towards COVID-19 and its preventive measures, without significant changes in the short term despite a relaxation of government-mandated preventive measures. These results provide relevant information in case of a new health emergency due to respiratory viruses.

Acute flaccid paralysis (AFP) surveillance: challenges and opportunities from 18 years' experience, Spain, 1998 to 2015.

Acute flaccid paralysis (AFP) surveillance is key for global polio eradication. It allows detecting poliovirus (PV) reintroductions from endemic countries. This study describes AFP surveillance in Spain from 1998 to 2015. During this time, 678 AFP cases were reported to the Spanish National Surveillance Network. The mean notification rate was 0.58 AFP cases/100,000 population under 15 years old (range: 0.45/100,000-0.78/100,000). Two periods (P) are described: P1 (1998-2006) with the AFP notification rate ranging from 0.66/100,000 to 0.78/100,000, peaking in 2001 (0.84/100,000); and P2 (2007-2015) when the AFP rate ranged from 0.43/100,000 to 0.57/100,000, with the lowest rate in 2009 (0.31/100,000). No poliomyelitis cases were caused by wild PV infections, although two Sabin-like PVs and one imported vaccine-derived PV-2 were detected. Overall, 23 (3.4%) cases met the hot case definition. Most cases were clinically diagnosed with Guillain-Barré syndrome (76.9%; 504/655). The adequate stool collection rate ranged from 33.3% (7/21) to 72.5% (29/40). The annual proportion of AFP cases with non-polio enterovirus findings varied widely across the study period. AFP surveillance with laboratory testing for non-polio enteroviruses must be maintained and enhanced both to monitor polio eradication and to establish sensitive surveillance for prompt detection of other enteroviruses causing serious symptoms.

Influenza vaccine effectiveness in preventing inpatient and outpatient cases in a season dominated by vaccine-matched influenza B virus.

Studies that have evaluated the influenza vaccine effectiveness (VE) to prevent laboratory-confirmed influenza B cases are uncommon, and few have analyzed the effect in preventing hospitalized cases. We have evaluated the influenza VE in preventing outpatient and hospitalized cases with laboratory-confirmed influenza in the 2012-2013 season, which was dominated by a vaccine-matched influenza B virus. In the population covered by the Navarra Health Service, all hospitalized patients with influenza-like illness (ILI) and all ILI patients attended by a sentinel network of general practitioners were swabbed for influenza testing, and all were included in a test-negative case-control analysis. VE was calculated as (1-odds ratio) × 100. Among 744 patients tested, 382 (51%) were positive for influenza virus: 70% for influenza B, 24% for A(H1N1)pdm09, and 5% for A(H3N2). The overall estimate of VE in preventing laboratory-confirmed influenza was 63% (95% confidence interval (CI): 34 to 79), 55% (1 to 80) in outpatients and 74% (33 to 90) in hospitalized patients. The VE was 70% (41 to 85) against influenza B and 43% (-45 to 78) against influenza A. The VE against virus B was 87% (52 to 96) in hospitalized patients and 56% in outpatients (-5 to 81). Adjusted comparison of vaccination status between inpatient and outpatient cases with influenza B did not show statistically significant differences (odds ratio: 1.13; p = 0.878). These results suggest a high protective effect of the vaccine in the 2012-2013 season, with no differences found for the effect between outpatient and hospitalized cases.

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.

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.

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.

Using surveillance data to estimate pandemic vaccine effectiveness against laboratory confirmed influenza A(H1N1)2009 infection: two case-control studies, Spain, season 2009-2010.

BACKGROUND: Physicians of the Spanish Influenza Sentinel Surveillance System report and systematically swab patients attended to their practices for influenza-like illness (ILI). Within the surveillance system, some Spanish regions also participated in an observational study aiming at estimating influenza vaccine effectiveness (cycEVA study). During the season 2009-2010, we estimated pandemic influenza vaccine effectiveness using both the influenza surveillance data and the cycEVA study. METHODS: We conducted two case-control studies using the test-negative design, between weeks 48/2009 and 8/2010 of the pandemic season. The surveillance-based study included all swabbed patients in the sentinel surveillance system. The cycEVA study included swabbed patients from seven Spanish regions. Cases were laboratory-confirmed pandemic influenza A(H1N1)2009. Controls were ILI patients testing negative for any type of influenza. Variables collected in both studies included demographic data, vaccination status, laboratory results, chronic conditions, and pregnancy. Additionally, cycEVA questionnaire collected data on previous influenza vaccination, smoking, functional status, hospitalisations, visits to the general practitioners, and obesity. We used logistic regression to calculate adjusted odds ratios (OR), computing pandemic influenza vaccine effectiveness as (1-OR)*100. RESULTS: We included 331 cases and 995 controls in the surveillance-based study and 85 cases and 351 controls in the cycEVA study. We detected nine (2.7%) and two (2.4%) vaccine failures in the surveillance-based and cycEVA studies, respectively. Adjusting for variables collected in surveillance database and swabbing month, pandemic influenza vaccine effectiveness was 62% (95% confidence interval (CI): -5; 87). The cycEVA vaccine effectiveness was 64% (95%CI: -225; 96) when adjusting for common variables with the surveillance system and 75% (95%CI: -293; 98) adjusting for all variables collected. CONCLUSION: Point estimates of the pandemic influenza vaccine effectiveness suggested a protective effect of the pandemic vaccine against laboratory-confirmed influenza A(H1N1)2009 in the season 2009-2010. Both studies were limited by the low vaccine coverage and the late start of the vaccination campaign. Routine influenza surveillance provides reliable estimates and could be used for influenza vaccine effectiveness studies in future seasons taken into account the surveillance system limitations.

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.