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.

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.

A case of respiratory toxigenic diphtheria: contact tracing results and considerations following a 30-year disease-free interval, Catalonia, Spain, 2015.

In May 2015, following a 30-year diphtheria-free interval in Catalonia, an unvaccinated 6-year-old child was diagnosed with diphtheria caused by toxigenic Corynebacterium diphtheriae. After a difficult search for equine-derived diphtheria antitoxin (DAT), the child received the DAT 4 days later but died at the end of June. Two hundred and seventeen contacts were identified in relation to the index case, and their vaccination statuses were analysed, updated and completed. Of these, 140 contacts underwent physical examination and throat swabs were taken from them for analysis. Results were positive for toxigenic C. diphtheriae in 10 contacts; nine were asymptomatic vaccinated children who had been in contact with the index case and one was a parent of one of the nine children. Active surveillance of the 217 contacts was initiated by healthcare workers from hospitals and primary healthcare centres, together with public health epidemiological support. Lack of availability of DAT was an issue in our case. Such lack could be circumvented by the implementation of an international fast-track procedure to obtain it in a timely manner. Maintaining primary vaccination coverage for children and increasing booster-dose immunisation against diphtheria in the adult population is of key importance.

Descriptive study of severe hospitalized cases of laboratory-confirmed influenza during five epidemic seasons (2010-2015).

OBJECTIVE: The Plan of Information on Acute Respiratory Infections in Catalonia (PIDIRAC) included the surveillance of severe hospitalized cases of laboratory-confirmed influenza (SHCLCI) in 2009. The objective of this study was to determine the clinical, epidemiological and virological features of SHCLCI recorded in 12 sentinel hospitals during five influenza seasons. RESULTS: From a sample of SHCLCI recorded during the 5 influenza epidemics seasons from 2010-2011 to 2014-2015, Cases were confirmed by PCR and/or viral isolation in cell cultures from respiratory samples. A total of 1400 SHCLCI were recorded, 33% required ICU admission and 12% died. The median age of cases was 61 years (range 0-101 years); 70.5% were unvaccinated; 80.4% received antiviral treatment (in 79.6 and 24% of cases within 48 h after hospital admission and the onset of symptoms, respectively); influenza virus A [37.9% A (H1N1)pdm09, 29.3% A (H3N2)] was identified in 87.7% of cases. Surveillance of SHCLCI provides an estimate of the severity of seasonal influenza epidemics and the identification and characterization of at-risk groups in order to facilitate preventive measures such as vaccination and early antiviral treatment.

Immigrants do not transmit tuberculosis more than indigenous patients in Catalonia (Spain).

BACKGROUND: Immigrants may not transmit tuberculosis (TB) more than indigenous patients. The objective was to study the prevalence of TB infection among contacts of immigrant and indigenous TB patients and the risk factors associated with latent TB infection. METHODS: Contacts of TB cases recorded in 2005 and 2006 were surveyed using a standardized Health Department questionnaire. Infections were diagnosed using the tuberculin skin test (TST) (cut-off ≥ 5 mm). The risk of infection was determined by multivariate logistic regression and the adjusted odds ratios (aOR) with the 95% confidence intervals (CI) were calculated. RESULTS: The study of contacts was completed in 1329 cases of TB. The prevalence of infection was 32.3% (3038/9406) in all contacts, 41.4% in contacts of immigrant cases and 29.2% in contacts of indigenous cases. In the multivariate analysis, immigrant index cases were not associated with an increased risk (aOR = 0.9; 95%CI: 0.8-1.0). The prevalence of TST conversion was 10.0% (296/2969) in all contacts, 11.2% in immigrant contacts and 9.7% in indigenous contacts (p = 0.158). CONCLUSIONS: Immigrants do not transmit TB more than indigenous TB patients. Infections which may have occurred in the countries of origin of immigrants were detected by the systematic study of contacts.

Epidemiological analysis of severe hospitalized 2009 pandemic influenza A (H1N1) cases in Catalonia, Spain.

From 25th April 2009 to 20th January 2010, 771 laboratory confirmed cases of 2009 pandemic influenza A (H1N1) were admitted to intensive care units (ICU) or hospitalized in medical wards with clinical criteria of severe disease (hospitalized pneumonias, multiorganic failure, septic shock or admitted to ICU or death while hospitalized). 82% of cases were hospitalized between epidemiological week 43 and 48 (25th October - 5th December 2009). Median age of patients was 40 years (range 0-89 years) and 56% were males. 38.7% cases were in the 15-44 year age-group, 29.4% in the 45-64 and 21.8% were children under 15 years of age. 36.8% were admitted to an ICU and 48 died. Underlying conditions were absent in 29% of patients (up to 38% among those under 15 years old). Differences in the prevalence of underlying conditions were found between children and adults. In children less than 15 years old, asthma (16.2%), other respiratory diseases (12.7%), cognitive disorders (10.2%), epilepsy (8.7%) and neuromuscular disorders (7.1%) were the most frequent. In adults, chronic obstructive pulmonary disease (14.8%), cardiovascular diseases (12.6%), asthma (11.5%), diabetes (11.2%) and morbid obesity (10.6%) were the most frequent. Further surveillance is needed to better characterize the epidemiology of this pandemic.