Vaccinated COVID-19 Index Cases Are Less Likely to Transmit SARS-CoV-2 to Their Household Contacts: A Cohort Study.

The aim of this study was to evaluate the impact of index case vaccination on SARS-CoV-2 transmission to household contacts. In our epidemiological cohort study (May 2022-November 2023), we surveyed registered index case vaccination status and test results for contacts (testing on day 0, and on day 7 for negative contacts) and calculated the secondary attack rate (SAR), i.e., newly infected contacts/susceptible included contacts. The association of the independent variable, index case COVID-19 vaccination (yes/no), with household contact infection was determined using the adjusted odds ratio (aOR) and its 95% confidence interval (CI). We recorded 181 index cases and 314 contacts, of whom 250 agreed to participate; 16 contacts were excluded upon testing positive on day 0. Of the 234 included contacts, 49.1% were women, and the mean (SD) age was 51.9 (19.8) years. The overall SAR of 37.2% (87/234) was lower in the contacts of both vaccinated index cases (34.9% vs. 63.2%; p = 0.014) and index cases with a previous SARS-CoV-2 infection history (27.0% vs. 46.3%; p = 0.002). Index case vaccination showed a protective effect against infection for their household contacts (aOR = 0.21; 95% CI: 0.07, 0.67). The household SAR was high when the Omicron variant circulated. Vaccinated index cases were less likely to transmit SARS-CoV-2 to their contacts.

Risk of tuberculosis among pulmonary tuberculosis contacts: the importance of time of exposure to index cases.

INTRODUCTION: The intensity of exposure to index cases of tuberculosis [TB] may increase the risk of TB in their contacts. The aim was to determine TB risk factors among contacts of TB index cases. METHODS: A cohort study was carried out in the contacts of pulmonary TB cases registered by the epidemiological surveillance network from 01/01/2019 to 06/30/2021. The factors associated with the risk of TB in contacts were determined using the adjusted odds ratio [aOR] and its 95% confidence interval [CI]. RESULTS: From 847 TB cases, 7087 contacts were identified. The prevalence of TB was 2.0% [145/7087] and was higher in < 5 years compared to those ≥ 65 years [4.4% versus 1.2%; p < 0.001], in those exposed ≥ 6 h daily [4%], and < 6 h daily [1.6%] with respect to weekly exposure of < 6 h [0.7%; p < 0.001]. Those contacts exposed ≥ 6 h daily [aOR= 6.9; 95%CI:2.1-22.1], < 5 years [aOR= 8.3; 95%CI:1.8-37.8] and immigrants [aOR= 1.7; 95%CI:1.1-2.7] had a higher risk of TB. CONCLUSIONS: The risk of TB increases with the time of exposure to the index case and this risk is also higher in < 5 years and immigrants. Contact tracing has a high yield for detecting new cases of TB.

Two successive outbreaks of acute gastroenteritis due to norovirus GII.6 in a holiday camp house.

When two outbreaks occur in the same institution within a short period of time, an important health and social concern is generated. Two gastroenteritis outbreaks occurring a week apart in the same facility were reported in Lleida, Spain, in 2018. The objective of this study was to describe the clinical, epidemiological and microbiological investigation carried out and to determine the risk factors. Demographic data, food consumption and symptoms were collected. Health inspections of the facility were carried out. Risk ratio and their 95% confidence intervals were estimated for the implication of each food consumed. The attack rate was 89.7% in the first outbreak and 69.6% in the second outbreak. The most frequent symptoms in the first and second outbreak were abdominal pain (88.5% and 100%, respectively), vomiting (80.8% and 87.5%, respectively) and nausea (69.2% and 81.3%, respectively). The first outbreak was associated with the consumption of a salad and the second with a cheese omelet. Norovirus GII.6 was detected by RT-PCR and sequenced in both groups of students and in the food handlers who prepared the meals. These results highlight the importance of exclusion from work of food handlers with gastroenteritis, the adequate availability of mechanisms for correct hand washing and the correct cleaning of surfaces.

Epidemiology of GII.4 and GII.2 norovirus outbreaks in closed and semi-closed institutions in 2017 and 2018.

Norovirus infections are a leading cause of acute gastroenteritis outbreaks worldwide, with genotypes GII.2 and GII.4 being the most prevalent. The aim of this study was to compare the characteristics of GII.2 and GII.4 norovirus outbreaks reported in Catalonia in closed or semi-closed institutions in 2017 and 2018. The epidemiological and clinical characteristics of GII.2 and GII.4 outbreaks were compared using the chi-square test or Fisher's exact test for categorical variables and the Mann-Whitney U test for continuous variables. Odds ratios and their 95% confidence intervals were estimated. 61 outbreaks were reported: GII.4 was the causative agent in 12 outbreaks (30%) and GII.2 in 9 outbreaks (22.5%). GII.2 outbreaks were detected more frequently in schools or summer camps (66.7%) and GII.4 outbreaks in nursing homes (91.7%) (p = 0.01). Ninety-three people were affected in GII.2 outbreaks and 94 in GII.4 outbreaks. The median age was 15 years (range: 1-95 years) in GII.2 outbreaks and 86 years (range: 0-100 years) in GII.4 outbreaks (p < 0.001). Nausea, abdominal pain, and headache were observed more frequently in persons affected by GII.2 outbreaks (p < 0.05). Symptomatic cases presented a higher viral load suggestive of greater transmission capacity, although asymptomatic patients presented relevant loads indicative of transmission capacity.

COVID-19 vaccination coverage and associated factors in seasonal fruit workers in Lleida.

Objectives: Seasonal fruit workers are a high-risk group for SARS-COV-2 infection. We aimed to estimate vaccination coverage and factors associated with vaccination in seasonal fruit workers. Methods: We carried out an anonymous survey of seasonal fruit workers in the 2021 campaign in Baix Segria region and Lleida city (Spain) on vaccination, knowledge and attitudes about the COVID-19 vaccine. Univariate and bivariate descriptive analyses were performed comparing vaccinated versus non-vaccinated. Multivariate analysis was performed using to assess factors associated to vaccination uptake. Results: We included 286 seasonal workers. The prevalence of confirmed COVID-19 background was 39.5% and overall vaccination coverage was 78.7%. Factors associated with vaccination were age (aOR = 0.96; 95% CI: 0.94-0.99), good knowledge of disease (aOR = 1.87; 95% CI : 1.01-3.47) and having a high-perceived vaccine effectiveness (aOR = 2.94; 95% CI : 1.50-5.73). High vaccination coverage in workers was associated to knowledge (OR = 3.69; 95% CI: 1.61-8.48), safe transport (OR = 2.84; 95% CI: 1.40-5.76) and appropriate housing (OR = 2.62; 95% CI: 1.25-5.46) as important non-pharmacological measures to reduced transmission. Conclusion: The study confirms the high prevalence of COVID-19 history and moderate vaccination coverage in seasonal fruit workers. Health education programs to improve knowledge about COVID-19 and its vaccination can help improve vaccination uptake.

Objetivos: Los trabajadores temporales de la fruta son un grupo de alto riesgo de infección por SARS-COV-2. El objetivo fue estimar la cobertura vacunal y los factores asociados a la vacunación en los trabajadores temporales de la fruta. Métodos: Se realizó una encuesta anónima a los temporeros de la campaña de la fruta 2021 en la comarca del Baix Segrià y en la ciudad de Lleida sobre la vacunación, y los conocimientos y actitudes sobre la vacuna de la COVID-19. Se realizaron análisis descriptivos y bivariantes comparando los vacunados con los no vacunados y se realizó un análisis multivariante para evaluar los factores asociados a la vacunación. Resultados: Se incluyeron 286 trabajadores temporales. La prevalencia de haber sido COVID-19 confirmado previamente fue del 39,5% y la cobertura global de vacunación fue del 78,7%. Los factores asociados a la vacunación fueron la edad (ORa = 0,96; IC 95%: 0,94-0,99), el conocimiento correcto de la enfermedad (ORa = 1,87; IC 95% : 1,01-3,47) y tener una alta percepción de la eficacia de la vacuna (ORa = 2,94; IC 95% : 1,50-5,73). Se observó una alta cobertura vacunal en los trabajadores manifestaron que los conocimientos de la enfermedad (OR = 3,69; IC 95%: 1,61-8,48), el transporte seguro (OR = 2,84; IC 95%: 1,40-5,76) y el alojamiento adecuado (OR = 2,62; IC 95%: 1,25-5,46) son importantes medidas para reducir la transmisión. Conclusiones: El estudio confirma la alta prevalencia de haber pasado la COVID-19 y la moderada cobertura de vacunación en los trabajadores estacionales de la fruta. Los programas de educación sanitaria para mejorar el conocimiento sobre el COVID-19 y su vacunación pueden ayudar a mejorar la aceptación de la vacunación.

Impact of the COVID-19 pandemic on contact tracing of patients with pulmonary tuberculosis.

BACKGROUND: The COVID-19 pandemic could have negative effects on tuberculosis (TB) control. The objective was to assess the impact of the pandemic in contact tracing, TB and latent tuberculosis infection (LTBI) in contacts of patients with pulmonary TB in Catalonia (Spain). METHODS: Contact tracing was carried out in cases of pulmonary TB detected during 14 months in the pre-pandemic period (1 January 2019 to 28 February 2020) and 14 months in the pandemic period (1 March 2020 to 30 April 2021). Contacts received the tuberculin skin test and/or interferon gamma release assay and it was determined whether they had TB or LTBI. Variables associated with TB or LTBI in contacts (study period and sociodemographic variables) were analyzed using adjusted odds ratio (aOR) and the 95% confidence intervals (95% CI). RESULTS: The pre-pandemic and pandemic periods showed, respectively: 503 and 255 pulmonary TB reported cases (reduction of 50.7%); and 4676 and 1687 contacts studied (reduction of 36.1%). In these periods, the proportion of TB cases among the contacts was 1.9% (84/4307) and 2.2% (30/1381) (P = 0.608); and the proportion of LTBI was 25.3% (1090/4307) and 29.2% (403/1381) (P < 0.001). The pandemic period was associated to higher LTBI proportion (aOR = 1.3; 95% CI 1.1-1.5), taking into account the effect on LTBI of the other variables studied as sex, age, household contact and migrant status. CONCLUSIONS: COVID-19 is affecting TB control due to less exhaustive TB and LTBI case detection. An increase in LTBI was observed during the pandemic period. Efforts should be made to improve detection of TB and LTBI among contacts of TB cases.

Norovirus outbreaks in long-term care facilities in Catalonia from 2017 to 2018.

Norovirus is the leading cause of outbreaks of acute viral gastroenteritis. We carried out this study to investigate outbreaks in long-term care facilities reported in 2017 and 2018 in Catalonia (Spain). The characteristics of the centers, exposed persons and the genogroups responsible were analyzed. Viral loads were estimated. The attack rate (AR) of the outbreaks studied, and the rate ratio (RR) and the odds ratio (OR) and their 95% confidence intervals as measures of association were calculated. The mean cycle thresholds were compared using the t-test for independent means. We included 30 outbreaks (4631 exposed people). The global AR was 25.93%. The RR of residents vs. staff was 2.28 (95% CI 2.0-2.6). The RR between AR in residents with total or severe dependence vs. residents with moderate, low or no-dependence was 1.23 (95% CI 1.05-1.45). The AR were higher in smaller centers than in larger ones (38.47% vs. 19.25% and RR 2; 95% CI 1.82-2.2). GII was responsible for 70% of outbreaks. No association was found between the genogroup and presenting symptoms (OR 0.96; 95% CI 0.41-2.26). Viral loads were higher in symptomatic than in asymptomatic patients (p = 0.001).

Effectiveness of maternal pertussis vaccination in protecting newborn: A matched case-control study.

INTRODUCTION: The objective was to estimate the effectiveness of maternal pertussis vaccination in protecting infants aged < 2 months. METHODS: We performed a case-control study. Laboratory-confirmed cases aged <8 weeks at disease onset were identified and 2-4 matched-controls born within ± 15 days of the case were included. Information was obtained from healthcare providers and maternal interviews. Odds ratios (OR) were calculated using multivariable conditional logistic regression. Vaccine effectiveness (VE) was estimated as (1 - OR) × 100%. RESULTS: 47 cases and 124 controls were studied. The mean age (in days) (39.8 ± 12.7 vs. 40.8 ± 13.2), weeks of gestation (38.8 vs. 39.1, p = 0.43) and mean birth weight (3.309 vs. 3.253 kg, p = 0.55) were comparable between cases and controls. Mothers of cases were less frequently vaccinated in the third trimester (59.6% vs. 83.9%, p <0.001). The VE of maternal vaccination in pregnancy was 88.0% (95%CI 53.8% -96.5%), and was slightly higher in those vaccinated before the 32nd week of gestation (88.5% vs 87.8%). CONCLUSION: Pertussis vaccination in pregnancy is very effective in reducing pertussis in children aged < 2 months. Vaccination before and after the 32nd week of pregnancy are equally effective in reducing the risk of pertussis.

Clinico-epidemiological characteristics of men and women with a new diagnosis of chronic obstructive pulmonary disease: a database (SIDIAP) study.

BACKGROUND: The risk of developing Chronic Obstructive Pulmonary Disease (COPD), the associated comorbidities and response to bronchodilators might differ in men and women. The objective of this study was to determine the prevalence of COPD and the clinic-epidemiological characteristics of primary care patients with COPD according to gender. METHODS: This is a cross-sectional study using electronic healthcare records Catalonia (Spain), during the 01/01/2012-31/12/2017 period. Patients from the SIDIAP database (System for the Development of Research in Primary Care) were included (5,800,000 patients registered in 279 primary care health centres). Clinic-demographic characteristics, comorbidities and blood tests results were collected for each patient. Adjusted OR (ORa) with logistic regression methods were used to determine variables associated with men and women. RESULTS: From an initial sample of 800,899 people, 24,135 (3%) were considered COPD patients, and 22.9%were women. The most common risk factors in women were bronchiectasis (ORa = 20.5, SD = 19.5-21.6), age > 71 years (ORa = 18.8; SD = 17.3-20.5), cor pulmonale (ORa = 5.2; SD = 4.3-6.7) and lung cancer (ORa = 3.6, SD = 3.2-4.0). Men and women presented the same comorbidities, though the strength of association was different for each gender. CONCLUSIONS: Patients suffering high comorbidity rates. Comorbidities are similar in men and women, although the strength of association varies according to gender. Women are more susceptible to the harmful effects of smoking and present a higher proportion of bronchiectasis and OSAS.

Involvement of Workers in Closed and Semiclosed Institutions in Outbreaks of Acute Gastroenteritis Due to Norovirus.

Norovirus outbreaks frequently occur in closed or semiclosed institutions. Recent studies in Catalonia and various countries indicate that, during outbreaks in these institutions, norovirus is detected in between 23% and 60% of workers, and the prevalence of infection in asymptomatic workers involved in outbreaks ranges from 17% to 40%. In this work, we carried out a prospective study to investigate the involvement of workers in closed and semiclosed institutions during outbreaks. The attack rates (ARs) and the rate ratios (RRs) were calculated according to the type of transmission and occupational category. The RRs and 95% confidence intervals (CIs) between workers and users were calculated. The mean cycle of quantification (Cq) values were compared according to the genogroup and the presence of symptoms. ARs were higher in person-to-person transmission than in common vehicle outbreaks, and 38.8% of workers were symptomatic. The RR between workers and users was 0.46 (95% CI 0.41-0.52). The ARs in workers were high, particularly in workers with closer contact with users. The mean Cq was lower in patients than in asymptomatic infected persons, although the difference was only significant for genogroup I (GI). The frequency of asymptomatic infected persons suggests that personal hygiene measures should be followed by all workers in the centers affected.

Diabetes as a risk factor for severe exacerbation and death in patients with COPD: a prospective cohort study.

BACKGROUND: Type 2 diabetes comorbidity is common in patients with COPD. One of the most frequent causes of hospital admission in patients with COPD are exacerbations. METHODS: Prospective cohort study, which included 512 patients with COPD recruited in a primary care centre in Mollerussa (Lleida, Spain). Inclusion criteria were: patients >40 years of age with COPD according to the Global Initiative for Chronic Obstructive Lung Disease. Variables collected were as follows: age, gender, civil status, education level, smoking habit, severity (Global Initiative for Chronic Obstructive Lung Disease), comorbidities (Charlson), history of severe exacerbations, dyspnoea (mMRC), BODEx, EuroQol 5 D and depression (HAD). Logistic regression was used to determine the association of diabetes with risk of hospital admission and death. RESULTS: Prevalence of diabetes was 25.8%. During the second year of follow up, 18.2% of patients with COPD and diabetes were admitted for exacerbation, in comparison with 8.9% non-diabetic COPD patients. The variables associated with hospital admission were diabetes (ORa=1.54); gender (men, ORa=1.93); age (ORa=1.02); number of hospital admissions during the previous year: 1 (ORa=2.83) or more than one admission (ORa=4.08); EuroQol 5 D (ORa=0.76) and BODEx (ORa=1.24). With the exclusion of BODEx, all these variables were associated with a higher risk of death. CONCLUSION: Prevalence of diabetes is high in patients suffering from COPD. COPD patients with diabetes are at higher risk of severe exacerbation and death. The suggested predictive model could identify patients at higher risk so that adequate preventive and therapeutic measures can be implemented.

[Prevalence and characteristics of chronic obstructive pulmonary disease in non-smokers]. / Prevalencia y características de la enfermedad pulmonar obstructiva crónica en no fumadores.

OBJECTIVE: The objective of the study was to know the profile of patients diagnosed with chronic obstructive pulmonary disease (COPD) and who have never been smokers. DESIGN: A transversal study. LOCATION: Primary Care Centre of Pla d'Urgell (Primary care setting in Lleida, Spain). PARTICIPANTS: 512 patients older than 40 years with COPD from Primary Care Centre of Pla d'Urgell with a compatible spirometry [forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio <0.7) to the beginning of the study. MAIN MEASUREMENTS: The dependent variable was de COPD in non-smokers and the independents were variables collected from the information on the respiratory clinical history, the risk factors of the patients and on quality of life. We designed a predictor model of COPD in non-smokers compared to smokers. RESULTS: 33.2% of COPD patients had never been smokers, 59.4% of whom were women. The average FEV1 for non-smokers was 70.5 (SD=17.1), higher than 62.6 (SD=18.5) for smokers/former smokers (p<0.001). The coverage of pneumococcal vaccination 23V was better in non-smokers (75.3%), p<0.001. COPD in non-smokers (compared to smokers/former smokers) were: mostly women (OR=16.46), older (OR=1.1), with better FEV1 (OR=1.1), better perception of quality, EuroQoL-5D (OR=0.8), with lower prevalence of diabetes (OR=0.5), lower level of studies (OR=0.2), and with fewer previous hospitalizations (OR=0.3). CONCLUSIONS: The study evidences a high proportion of non-smokers in COPD patients. Our study aims that older women with less severity would be associated with an increased risk of COPD in non-smokers. It seems to indicate that COPD in non-smokers would appear at later ages and would be milder than smoking-related COPD.

Mental disorders in chronic obstructive pulmonary diseases.

PURPOSE: Anxiety and depression are underdiagnosed in chronic obstructive pulmonary disease (COPD) patients. Few studies have tried to identify their association with hospitalization (severe exacerbation). The objective of this study was to determine whether the anxiety/depression was associated with severe exacerbation. DESIGN AND METHODS: A prospective cohort study, based on a sample of 512 patients diagnosed with COPD originating from primary care in a rural area in Lleida (Spain) and monitored between November 1, 2012 and October 31, 2014. For each patient, variables of interest were recorded; they were administered the HADS (Hospital Anxiety and Depression Scale) test to determine the possible presence of anxiety/depression, and its association with severe exacerbation was analyzed using a logistic regression model. FINDINGS: Initially, the prevalence of anxiety/depression was 15.6%. The incidence of global hospitalization in the first year was 8.2% and 11.3% in the second year. In patients with anxiety/depression, it increased to 17.5% in the first year and 18.8% in the second year. In the multivariate regression model, the diagnosis of anxiety/depression almost doubled the risk of hospitalization (OR = 1.94) (p < .041). PRACTICE IMPLICATIONS: Anxiety and depression are associated with an increased risk of hospitalization. Intervention studies are needed to evaluate the effects of anxiety/depression in the hospitalization.

Prevalence of chronic obstructive pulmonary disease (COPD) not diagnosed in a population with cardiovascular risk factors. / Prevalencia de enfermedad pulmonar obstructiva crónica no diagnosticada en una población con factores de riesgo cardiovascular.

BACKGROUND AND OBJECTIVE: The magnitude of undiagnosed COPD in our population with cardiovascular risk factors (CVRF) is unknown. The objective of this study was to estimate the prevalence of undiagnosed COPD and its specific characteristics in a population with CVRF. MATERIALS AND METHODS: Study the prevalence of COPD in patients with CVRF. Spirometry was performed between 01/01/2015 and 12/31/2016 and the percentage of patients with COPD, who had not previously been diagnosed, was determined. Each patient's variables of interest were recorded; the records of patients who had spirometry showing COPD were checked to confirm whether a diagnosis had been recorded or not. The association of undiagnosed COPD with different independent variables was determined with adjusted odds ratio (aOR) by non conditional logistic regression models. RESULTS: 2,295 patients with CVRF were studied. The overall prevalence of COPD was 14.5%. An underdiagnosis of 73.3% was observed. Newly diagnosed COPD vs. undiagnosed COPD showed to be higher in women (74.1% vs. 36.0%; P=.081), non-smokers (21.3% vs. 12.4%; P=.577), mild cases (GOLD1) (42.6% vs. 32.4%, P=.008) and cases with lower than average HbA1c (5.5% vs. 5.6%; P=.008) and uric acid (5.1mg/dL vs. 5.6mg/dL; P=.011). The variables associated with undiagnosed COPD were: women (aOR=1.27; 95%CI: 0.74-2.17; P=.383); age (aOR=0.94; 95%CI: 0.87-0.99; P=.018); smokers (smoker/non-smoker) (aOR=0.47; 95%CI: 0.22-1.01; P=.054) and HbA1c (%) (aOR=0.45; 95%CI: 0.23-0.88; P=.019). CONCLUSIONS: The under-diagnosis of COPD is very high. The contact patients aged between 50 and 65 years-old who have CVRF with their health system should be reassessed, and they need to ask for a spirometry.

Overview of the Impact of Depression and Anxiety in Chronic Obstructive Pulmonary Disease.

BACKGROUND: Anxiety and depression are common entities in patients diagnosed with COPD. However, the impact that they have on the exacerbation of illness is scarcely studied. OBJECTIVE: To determine if the presence of anxiety and depression is associated with a greater risk of frequent exacerbation (≥2 per year) in patients diagnosed with COPD. PATIENTS AND METHODS: A cohort study that analysed frequent exacerbation and associated factors in 512 patients monitored during 2 years. Exacerbations were defined as events that required antibiotic/s and/or systemic corticosteroids (moderate) or hospitalization (serious). Variables of interest were recorded for each patient, including anxiety and depression (Hospital Anxiety and Depression Scale), and we analysed their association with frequent exacerbation through the adjusted odds ratio (aOR) by means of a logistic regression model. RESULTS: The prevalence of anxiety/depression at the start of the study was of 15.6%. During the 2 years of monitoring, 77.9% of the patients suffered at least moderate-to-severe exacerbation. 54.1% were frequent exacerbators. Anxiety/depression were strongly associated with moderate-severe frequent exacerbation in the crude analysis (ORc = 2.28). In the multivariate analysis, the risk factors also associated with frequent exacerbation were being overweight (aOR 2.78); obesity (aOR 3.02); diabetes (aOR 2.56) and the associated comorbidity (BODEx) (ORa = 1.45). CONCLUSIONS: The prevalence of anxiety/depression in COPD patients is high, and they are relevant risk factors in frequent exacerbation although the effect is lower in the multivariate analysis when adjusting for different variables strongly associated with exacerbation.

Factors influencing the spread of pertussis in households: a prospective study, Catalonia and Navarre, Spain, 2012 to 2013.

We aimed to investigate transmission rates of pertussis in household contacts of cases and factors associated with transmission. A prospective epidemiological study was conducted in 2012 and 2013 to determine the incidence of pertussis among household contacts of reported cases in Catalonia and Navarre, Spain. An epidemiological survey was completed for each case and contact, who were followed for 28 days to determine the source of infection (primary case) and detect the occurrence of secondary cases. Odds ratios (ORs) were used to estimate the effectiveness of vaccination and chemoprophylaxis in preventing new cases, using the formula (1 - OR) × 100. For the 688 primary cases, a total of 2,852 contacts were recorded. The household transmission rate was 16.1% (459/2,852) and rose according to the age (> 18 years) and lack of immunisation of the primary cases, and also the age (0-18 years), family relationship (siblings and children), lack of vaccination and chemoprophylaxis of contacts. Pertussis vaccine effectiveness in preventing new cases was 65.0% (95% confidence interval (CI): 11.6 to 86.2) for full vaccination (≥ 4 doses) and 59.7% (95% CI: -6.8 to 84.8) for incomplete vaccination (< 4 doses). The effectiveness of chemoprophylaxis was 62.1% (95% CI: 40.3 to 75.9). To reduce household transmission, contacts should be investigated to detect further cases and to administer chemoprophylaxis. The current vaccination status of cases and contacts can reduce household transmission.

Person-to-person transmission of norovirus resulting in an outbreak of acute gastroenteritis at a summer camp.

BACKGROUND: A significant proportion of norovirus (NV) gastroenteritis outbreaks described in the Spanish literature have been because of contaminated food or water. AIM: This study describes an outbreak of acute gastroenteritis because of NV in which there was person-to-person transmission. MATERIALS AND METHODS: A retrospective cohort study was carried out; we established the case definition for primary and secondary cases. An epidemiological survey was designed, including possible food exposures, and clinical and laboratory data. Water and stool samples were taken from affected individuals and food handlers. The presence of NV was detected using a reverse transcription-PCR assay. We analyzed the risk of gastroenteritis using relative risk and its 95% confidence interval as the measure of association, and estimated the basic reproductive number (R0). RESULTS: The primary attack rate was 45.0%, with no significant differences between sexes. The secondary attack rate during the camp stay was 22.7%. The basic reproductive number for 5 days was R0=2.62. The most frequent symptoms were abdominal pain (85.7%) and vomiting (81.9%). Epidemiological analysis showed no association with food or drinking water. A total of 66.6% (8/12) of stool samples tested positive for NV (genogroup II). CONCLUSION: Control measures in general, and hand hygiene in particular, should be extended to the families once the children return home, to prevent secondary cases in NV outbreaks.