Cycle Threshold Values of SARS-CoV-2 RT-PCR during Outbreaks in Nursing Homes: A Retrospective Cohort Study.

Backgound/Objectives: Cycle threshold (Ct) values of SARS-CoV-2 real-time reverse transcriptase-polymerase chain reaction (RT-PCR) tests are associated with infectivity and viral load, and they could be an aid in forecasting the evolution of SARS-CoV-2 outbreaks. The objective was to know the Ct values related to the incidence and reinfection of SARS-CoV-2 in successive outbreaks, which took place in nursing homes in Castellon (Spain) during 2020-2022, and to test its usefulness as an instrument of epidemic surveillance in nursing homes. METHODS: a retrospective cohort design with Poisson regression and multinomial logistic regression were used. RESULTS: We studied four nursing home SARS-CoV-2 outbreaks, and the average infection rate, reinfection rate, and case fatality were 72.7%, 19.9%, and 5.5%, respectively; 98.9% of residents were vaccinated with three doses of a mRNA SARS-CoV-2 vaccine. Ct values for first infections and reinfections were 27.1 ± 6.6 and 31.9 ± 5.4 (p = 0.000). Considering Ct values ≥ 30 versus <30, residents with reinfections had Ct values higher than residents with a first infection, an adjusted relative risk of 1.66 (95% Confidence interval 1.10-2.51). A sensitivity analysis confirmed these results. CONCLUSIONS: Reinfection and SARS-CoV-2 vaccination (hybrid immunity) could protect against severe disease better than vaccination alone. High Ct values suggest lower transmission and severity. Its value can be useful for surveillance and forecasting future SARS-CoV-2 epidemics.

Underreporting of Cases in the COVID-19 Outbreak of Borriana (Spain) during Mass Gathering Events in March 2020: A Cross-Sectional Study.

Determining the number of cases of an epidemic is the first function of epidemiological surveillance. An important underreporting of cases was observed in many locations during the first wave of the COVID-19 pandemic. To estimate this underreporting in the COVID-19 outbreak of Borriana (Valencia Community, Spain) in March 2020, a cross-sectional study was performed in June 2020 querying the public health register. Logistic regression models were used. Of a total of 468 symptomatic COVID-19 cases diagnosed in the outbreak through anti-SARS-CoV-2 serology, 36 cases were reported (7.7%), resulting in an underreporting proportion of 92.3% (95% confidence interval [CI], 89.5-94.6%), with 13 unreported cases for every reported case. Only positive SARS-CoV-2 polymerase chain reaction cases were predominantly reported due to a limited testing capacity and following a national protocol. Significant factors associated with underreporting included no medical assistance for COVID-19 disease, with an adjusted odds ratio [aOR] of 10.83 (95% CI 2.49-47.11); no chronic illness, aOR = 2.81 (95% CI 1.28-6.17); middle and lower social classes, aOR = 3.12 (95% CI 1.42-6.85); younger age, aOR = 0.97 (95% CI 0.94-0.99); and a shorter duration of illness, aOR = 0.98 (95% CI 0.97-0.99). To improve the surveillance of future epidemics, new approaches are recommended.

[Brote de la COVID-19 en una residencia en ancianos correctamente vacunados. Influencia de la inmunidad híbrida en la carga viral, el riesgo de infección y el riesgo de progresión de la enfermedad]. / COVID-19 outbreak in a properly vaccinated nursing home. Influence of hybrid immunity on viral load, risk of infection and risk of disease progression.

OBJECTIVE: This study addressed a COVID-19 outbreak in a nursing home, where the residents were vaccinated with two doses of Comirnaty® and thirty of them had previously had the infection. Outbreaks in closed communities are opportunities to study the entire clinical spectrum of the disease and, as in this case, the effect of hybrid immunity on transmission, infection progression and viral load. METHODS: A descriptive and retrospective cohort study in the resident population was carried out. Attack rates were calculated for one of four stages of the disease: infection, symptomatic infection, hospitalization, and death. Relative risks (RR) were then estimated using simple and multivariate Poisson regression for each of these stages. RESULTS: The attack rate was 59% (56/95). The clinical spectrum was the same in both sexes. There was a notable protective effect of hybrid immunity against transmission (67%). In terms of progression, those with hybrid immunity had a lower risk of symptomatic infection. Nasopharyngeal viral load was significantly lower in individuals with hybrid immunity and asymptomatic individuals, supporting the idea of lower transmissibility in this group. Age was identified as a risk factor for disease progression. Molecular analysis identified the Delta B.1.617.2 variant in the patients and an air sample, supporting aerosol transmission in closed, poorly ventilated environments. CONCLUSIONS: This study provides a comprehensive view of an outbreak in a vaccinated nursing home, highlighting the importance of hybrid immunity. The results support the individual consideration of previous infection history when assessing the risk of COVID-19, contributing to the understanding of the evolution of the pandemic in the future.

OBJECTIVE: Este estudio abordó un brote de la COVID-19 en una residencia de ancianos, donde los residentes estaban vacunados con dos dosis de Comirnaty® y treinta de ellos habían pasado anteriormente la infección. Los brotes en colectivos cerrados son oportunidades para estudiar todo el espectro clínico de la enfermedad y, como en este caso, el efecto de la inmunidad híbrida sobre la transmisión, la progresión de la infección y la carga viral. METHODS: Se realizó un estudio descriptivo y de cohortes retrospectivo en la población de residentes. Se calcularon las tasas de ataque para uno de cuatro estadios de la enfermedad: infección, infección sintomática, hospitalización y defunción. Después se estimaron los riesgos relativos (RR) mediante regresión de Poisson simple y multivariante para cada uno de esos estadios. RESULTS: La tasa de ataque fue del 59% (56/95). El espectro clínico fue igual en ambos sexos. Hubo un notable efecto protector de la inmunidad híbrida contra la transmisión (67%). En términos de progresión, aquellos con inmunidad híbrida presentaron un riesgo menor de infección sintomática. La carga viral nasofaríngea fue significativamente menor en individuos con inmunidad híbrida y asintomáticos, respaldando la idea de una menor transmisibilidad en este grupo. La edad se identificó como un factor de riesgo para la progresión de la enfermedad. El análisis molecular identificó la variante Delta B.1.617.2 en los pacientes y una muestra de aire, lo que respaldó la transmisión por aerosol en entornos cerrados y mal ventilados. CONCLUSIONS: Este estudio proporciona una visión integral de un brote en una residencia de ancianos vacunados, destacando la importancia de la inmunidad híbrida. Los resultados respaldan la consideración individual de la historia de infección previa al evaluar el riesgo de la COVID-19, contribuyendo a la comprensión de la evolución de la pandemia en el futuro.

Cellular Immunity of SARS-CoV-2 in the Borriana COVID-19 Cohort: A Nested Case-Control Study.

Our goal was to determine the cellular immune response (CIR) in a sample of the Borriana COVID-19 cohort (Spain) to identify associated factors and their relationship with infection, reinfection and sequelae. We conducted a nested case-control study using a randomly selected sample of 225 individuals aged 18 and older, including 36 individuals naïve to the SARS-CoV-2 infection and 189 infected patients. We employed flow-cytometry-based immunoassays for intracellular cytokine staining, using Wuhan and BA.2 antigens, and chemiluminescence microparticle immunoassay to detect SARS-CoV-2 antibodies. Logistic regression models were applied. A total of 215 (95.6%) participants exhibited T-cell response (TCR) to at least one antigen. Positive responses of CD4+ and CD8+ T cells were 89.8% and 85.3%, respectively. No difference in CIR was found between naïve and infected patients. Patients who experienced sequelae exhibited a higher CIR than those without. A positive correlation was observed between TCR and anti-spike IgG levels. Factors positively associated with the TCR included blood group A, number of SARS-CoV-2 vaccine doses received, and anti-N IgM; factors inversely related were the time elapsed since the last vaccine dose or infection, and blood group B. These findings contribute valuable insights into the nuanced immune landscape shaped by SARS-CoV-2 infection and vaccination.

[Impact of the pandemic on various infectious diseases with different epidemiological patterns of seasonality, transmission and age]. / Impacto de la pandemia en varias enfermedades infecciosas con patrones epidemiológicos distintos de estacionalidad, transmisión y edad.

OBJECTIVE: The COVID-19 pandemic has had a strong impact on other infectious diseases. The aim of this paper was to analyze the epidemiological changes that occurred during the pandemic in eight infectious diseases with different epidemiological patterns: influenza, respiratory syncytial virus, rotavirus, pneumococcus, Campylobacter, non-typhoid Salmonella, gonorrhea and herpes zoster. METHODS: From the Microbiological Surveillance Network, the time series of cases was traced from January 2017 to March 2023. Three periods were distinguished: reference, pandemic and beginning of the post-pandemic. The distribution by age and sex in these periods was analyzed. Incidence rates and rate ratios (RR) were calculated. These RRs and their 95% confidence intervals were estimated overall and by year of age in children under five years of age. RESULTS: Statistically significant differences were found in the impact that the pandemic had on each of these diseases. Some, after a period of epidemic silence, have revealed an intense post-pandemic rebound. The post-pandemic global RT increased for influenza (2.4), RSV (1.9) and gonorrhea (3.1); rotavirus recovered its pre-pandemic level (1.07); and pneumococcus (0.84), Campylobacter (0.83) and Salmonella (0.60) decreased. In children under 5 years of age, the patterns were specific and heterogeneous for each disease. CONCLUSIONS: The impact of the pandemic is very different in these diseases. Pediatric and respiratory-transmitted seasonal viral infections are the ones that are most affected, but with different patterns of recovery to normality. Gastrointestinal bacterial infections suffer fewer variations, except for rotavirus. Gonorrhea do not interrupt its increasing trend seen in the pre-pandemic. Shingles show a slight post-pandemic increase. Several diseases with different epidemiological patterns have been studied for a sufficient period to observe how the acute phase of the pandemic emerges.

OBJECTIVE: La pandemia de la COVID-19 ha tenido un fuerte impacto sobre otras enfermedades infecciosas. El objetivo de este trabajo fue analizar los cambios epidemiológicos acaecidos durante la pandemia en ocho enfermedades infecciosas con patrones epidemiológicos distintos: la gripe; virus respiratorio sincitial; rotavirus; neumococo; Campylobacter; Salmonella no tifoidea; gonococia; herpes zóster. METHODS: A partir de la Red de Vigilancia Microbiológica, se trazó la serie temporal de casos desde enero de 2017 a marzo de 2023. Se distinguieron tres periodos: prepandemia (referencia), pandemia e inicio de la pospandemia. Se analizó la distribución por edad y sexo en esos periodos. Se calcularon las tasas de incidencia y las razones de tasas (RT). Se estimaron esas RT globales y sus intervalos de confianza al 95% por cada año de edad en menores de cinco años. RESULTS: Se encontraron diferencias estadísticamente significativas en el impacto que la pandemia tuvo en cada una de esas enfermedades. Algunas, tras un periodo de silencio epidémico, revelaron un repunte intenso pospandémico. Incrementaron la RT global postpandémica la gripe (2,4), VRS (1,9) y gonococia (3,1); recuperó su nivel prepandémico el rotavirus (1,07); y disminuyeron el neumococo (0,84), Campylobacter (0,83) y Salmonella (0,60). En menores de cinco años, los patrones fueron específicos y heterogéneos para cada enfermedad. CONCLUSIONS: El impacto de la pandemia es muy diferente en estas enfermedades. Las infecciones víricas estacionales pediátricas y de transmisión respiratoria son las que más se ven afectadas, pero con patrones de recuperación de la normalidad distintos. Las infecciones bacterianas gastrointestinales sufren menos variaciones, salvo el rotavirus. La gonococia no interrumpe su tendencia al aumento avistada ya en la prepandemia. El herpes zóster muestra un ligero incremento pospandémico. Se han estudiado varias enfermedades con distinto patrón epidemiológico durante un periodo suficiente para observar cómo se produce la salida de la fase aguda de la pandemia.

Long COVID Prevalence and the Impact of the Third SARS-CoV-2 Vaccine Dose: A Cross-Sectional Analysis from the Third Follow-Up of the Borriana Cohort, Valencia, Spain (2020-2022).

BACKGROUND: In March 2020, a COVID-19 outbreak linked to mass gathering dinners at the Falles Festival in Borriana, Spain, resulted in an estimated attack rate of 42.6% among attendees. METHODS: In June 2022, we conducted a cross-sectional follow-up study of 473 adults aged 18 to 64 who attended the dinners at the Falles Festival in 2020, examining the cumulative experience after SARS-CoV-2 infection and vaccination responses. Data included demographic details, lifestyle habits, medical history, infection records, and vaccinations from a population-based vaccine registry. Blood samples were analyzed for SARS-CoV-2 antibodies and cellular immunity. We employed a doubly robust inverse-probability weighting analysis to estimate the booster vaccine dose's impact on long COVID prevalence and symptom count. RESULTS: A total of 28.1% of participants met the WHO criteria for long COVID, with older individuals showing higher rates. Long COVID diagnosis was less likely with factors including O blood group, higher occupational status, physical activity, three vaccine doses, strong SARS-CoV-2-S-reactive IFNγ-producing-CD8+ response, and infection during the Omicron period. Increased age, high or low social activity, underlying health conditions, a severe initial COVID episode, and reinfection were associated with higher long COVID likelihood. A booster dose, compared to one or two doses, reduced long COVID risk by 74% (95% CI: 56% to 92%) and symptom count by 55% (95% CI: 32% to 79%). CONCLUSION: Long COVID was prevalent in a significant portion of those who contracted COVID-19, underscoring the need for sustained follow-up and therapeutic strategies. Vaccinations, notably the booster dose, had a substantial beneficial effect on long-term infection outcomes, affirming the vaccination's role in mitigating SARS-CoV-2 infection consequences.

ABO Blood Groups and Incidence of COVID-19 in the Mass Gathering Events in Borriana (Spain), March 2020: A Retrospective Cohort Study.

Our objective was to estimate the incidence of COVID-19 and the ABO blood Groups in the mass-gathering events (MGEs) during the Falles Festival in Borriana (Spain) from 6-10 March 2020. We conducted a population-based retrospective cohort study and measured anti-SARS-CoV-2 antibodies and the ABO of participants. We performed laboratory COVID-19 tests and obtained the ABO in 775 subjects (72.8% of the original exposed cohort): O-group (45.2%), A-group (43.1%), B-group (8.5%) and AB-group (3.4%). Adjusted for confounding factors, including COVID-19 exposure during the MGEs, attack rates of COVID-19 for each ABO group were 55.4%, 59.6%, 60.2%, and 63.7%. The adjusted relative risks were for O-group 0.93 (95% Confidence Interval [CI] 0.83-1.04), for A-group 1.06 (95% CI 0.94-1.18), for B-group 1.04 (95%CI 0.88-1.24), and for AB-group 1.11 (95% CI 0.81-1.51) with no significant differences. Conclusions: Our results suggest no effect of ABO on COVID-19 incidence. We observed weak but not significant protection of the O-group and not a significantly greater infection risk for the remaining groups compared with the O-group. More studies are needed to resolve the controversies regarding the association between ABO and COVID-19.

Lifting COVID-19 mitigation measures in Spain (May-June 2020).

INTRODUCTION: The state of alarm was declared in Spain due to the COVID-19 epidemic on March 14, 2020, and established population confinement measures. The objective is to describe the process of lifting these mitigation measures. METHODS: The Plan for the Transition to a New Normality, approved on April 28, contained four sequential phases with progressive increase in socio-economic activities and population mobility. In parallel, a new strategy for early diagnosis, surveillance and control was implemented. A bilateral decision mechanism was established between the Spanish Government and the autonomous communities (AC), guided by a set of qualitative and quantitative indicators capturing the epidemiological situation and core capacities. The territorial units were established ad-hoc and could be from Basic Health Zones to entire AC. RESULTS: The process run from May 4 to June 21, 2020. AC implemented plans for reinforcement of core capacities. Incidence decreased from a median (50% of territories) of 7.4 per 100,000 in 7 days at the beginning to 2.5 at the end. Median PCR testing increased from 53% to 89% of suspected cases and PCR total capacity from 4.5 to 9.8 per 1000 inhabitants weekly; positivity rate decreased from 3.5% to 1.8%. Median proportion of cases with traced contacts increased from 82% to 100%. CONCLUSION: Systematic data collection, analysis, and interterritorial dialogue allowed adequate process control. The epidemiological situation improved but, mostly, the process entailed a great reinforcement of core response capacities nation-wide, under common criteria. Maintaining and further reinforcing capacities remained crucial for responding to future waves.

Lifting COVID-19 mitigation measures in Spain (May-June 2020).

Introduction: The state of alarm was declared in Spain due to the COVID-19 epidemic on March 14, 2020, and established population confinement measures. The objective is to describe the process of lifting these mitigation measures. Methods: The Plan for the Transition to a New Normality, approved on April 28, contained four sequential phases with progressive increase in socio-economic activities and population mobility. In parallel, a new strategy for early diagnosis, surveillance and control was implemented. A bilateral decision mechanism was established between the Spanish Government and the autonomous communities (AC), guided by a set of qualitative and quantitative indicators capturing the epidemiological situation and core capacities. The territorial units were established ad-hoc and could be from Basic Health Zones to entire AC. Results: The process run from May 4 to June 21, 2020. AC implemented plans for reinforcement of core capacities. Incidence decreased from a median (50% of territories) of 7.4 per 100,000 in 7 days at the beginning to 2.5 at the end. Median PCR testing increased from 53% to 89% of suspected cases and PCR total capacity from 4.5 to 9.8 per 1000 inhabitants weekly; positivity rate decreased from 3.5% to 1.8%. Median proportion of cases with traced contacts increased from 82% to 100%. Conclusion: Systematic data collection, analysis, and interterritorial dialogue allowed adequate process control. The epidemiological situation improved but, mostly, the process entailed a great reinforcement of core response capacities nation-wide, under common criteria. Maintaining and further reinforcing capacities remained crucial for responding to future waves.

Introducción: El 14 de marzo de 2020 España declaró el estado de alarma por la pandemia por COVID-19 incluyendo medidas de confinamiento. El objetivo es describir el proceso de desescalada de estas medidas. Métodos: Un plan de transición hacia una nueva normalidad, del 28 de abril, incluía 4 fases secuenciales incrementando progresivamente las actividades socioeconómicas y la movilidad. Concomitantemente, se implementó una nueva estrategia de diagnóstico precoz, vigilancia y control. Se estableció un mecanismo de decisión bilateral entre Gobierno central y comunidades autónomas (CCAA), guiado por un panel de indicadores cualitativos y cuantitativos de la situación epidemiológica y las capacidades básicas. Las unidades territoriales evaluadas comprendían desde zonas básicas de salud hasta CCAA. Resultados: El proceso se extendió del 4 de mayo al 21 de junio y se asoció a planes de refuerzo de las capacidades en las CCAA. La incidencia disminuyó de una mediana inicial de 7,4 por 100.000 en 7 días a 2,5 al final del proceso. La mediana de pruebas PCR aumentó del 53% al 89% de los casos sospechosos, y la capacidad total de 4,5 a 9,8 pruebas semanales por 1.000 habitantes; la positividad disminuyó del 3,5% al 1,8%. La mediana de casos con contactos trazados aumentó del 82% al 100%. Conclusión: La recogida y análisis sistemático de información y el diálogo interterritorial logaron un adecuado control del proceso. La situación epidemiológica mejoró, pero sobre todo, se aumentaron las capacidades, en todo el país y con criterios comunes, cuyo mantenimiento y refuerzo fue clave en olas sucesivas.

Incidence, Hospitalization, Mortality and Risk Factors of COVID-19 in Long-Term Care Residential Homes for Patients with Chronic Mental Illness.

Long-term care residential homes (LTCRH) for patients with chronic mental illness have suffered the enormous impact of COVID-19. This study aimed to estimate incidence, hospitalization, mortality, and risk factors of COVID-19 to prevent future epidemics. From March 2020 to January 2021 and before vaccination anti-SARS-CoV-2 begins, cumulate incidence rate (CIR), hospitalization rate (HR), mortality rate (MR), and risk factors of COVID-19 in the 11 LTCRH of two Health Departments of Castellon (Spain) were studied by epidemiological surveillance and an ecological design. Laboratory tests confirmed COVID-19 cases, and multilevel Poisson regression models were employed. All LTCRH participated and comprised 346 residents and 482 staff. Residents had a mean age of 47 years, 40% women, and suffered 75 cases of COVID-19 (CIR = 21.7%), five hospitalizations (HR = 1.4%), and two deaths (MR = 0.6%) with 2.5% fatality-case. Staff suffered 74 cases of the disease (CIR = 15.4%), one hospitalization (HR = 0.2%), and no deaths were reported. Risk factors associated with COVID-19 incidence in residents were private ownership, severe disability, residents be younger, CIR in municipalities where LTCRH was located, CIR in staff, and older age of the facilities. Conclusion: COVID-19 incidence could be prevented by improving infection control in residents and staff and modernizing facilities with increased public ownership.

Incidence, Mortality, and Risk Factors of COVID-19 in Nursing Homes.

During the period from March 2020 to January 2021, we performed an analysis of incidence, mortality, and risk factors of COVID-19 in nursing homes (NHs) in two health departments (HDs) of Castellon (Spain) 2021 through epidemiological surveillance and an ecological design. Laboratory-confirmed COVID-19 cases, cumulative incidence rate (CIR), and mortality rate (MR) of 27 NHs were collected. Information of residents, staff, and facilities was obtained by questionnaire. Multilevel Poisson regression models were applied. All NHs in the HDs participated with 2229 residents (median: 83 years old, 67.3% women) and 1666 staff. Among residents, 815 cases (CIR: 34.8 per 100) and 202 deaths (MR: 8.7 per 100, case fatality 21.0%) were reported and, among staff, 296 cases (CIR: 19.2 per 100) without deaths. Residents' CIR and MR increased with staff CIR, age of the building, residents/staff ratios, occupancy rate, and crowding index; CIR increased with private NH ownership, large NH size, large urban area, and the percentage of women residents; and MR was associated with residents' severe disabilities. In conclusion, several risk factors of COVID-19 incidence and mortality can be prevented by improving infection and quality controls, ameliorating residents/staff ratios, improving structural facilities, and increasing NH public ownership to avoid new outbreaks.

[Giardiasis in a paediatric population of the province of castellon. Clinical details and impact]. / Giardiosis en población pediátrica de la provincia de Castellón: clínica e impacto.

INTRODUCTION: Giardiasis is a gastrointestinal parasitosis that has a great public health impact. PATIENTS AND METHODS: Observational case study - in children under 15 years old in the Health Department 3 of the Province of Castellon (Spain), during the period 2012-2019. RESULTS: A total of 190 cases of giardiasis were recorded in children under 15 years old. The number of cases varied significantly according to age group and month of the year. There were 115 males. The most frequent symptoms were diarrhea and abdominal pain. The most commonly used treatment was standard metronidazole (80% of patients). Co-infection occurred in 13% of cases, and comorbidities in 36%, especially atopic dermatitis and lactose/fructose intolerance. Relapses and/or re-infections were recorded in 8%. All cases were diagnosed by conventional parasitological stool tests and complementary immunochromatography (63 cases). Thirty-five samples were positive for Giardia duodenalis by qPCR. The direct health cost per patient was 117€. A disease notification bias was detected between 2012-2016 at a national scale. CONCLUSIONS: Giardiasis is a current disease in Castellon, and should be considered as a probable diagnosis of gastrointestinal disease in a child under 4 years-old with diarrhea and abdominal pain. Its correct clinical and therapeutic management could reduce the possibility of worsening of the patient's condition and, additionally, would reduce the economic impact of the disease in terms of direct health costs.