COVID-19 vaccine effectiveness against hospitalization due to SARS-CoV-2: A test-negative design study based on Severe Acute Respiratory Infection (SARI) sentinel surveillance in Spain

Background

With the emergence of SARS‐CoV‐2, influenza surveillance systems in Spain were transformed into a new syndromic sentinel surveillance system. The Acute Respiratory Infection Surveillance System (SiVIRA in Spanish) is based on a sentinel network for acute respiratory infection (ARI) surveillance in primary care and a network of sentinel hospitals for severe ARI (SARI) surveillance in hospitals.

Methods

Using a test‐negative design and data from SARI admissions notified to SiVIRA between January 1 and October 3, 2021, we estimated COVID‐19 vaccine effectiveness (VE) against hospitalization, by age group, vaccine type, time since vaccination, and SARS‐CoV‐2 variant.

Results

VE was 89% (95% CI: 83–93) against COVID‐19 hospitalization overall in persons aged 20 years and older. VE was higher for mRNA vaccines, and lower for those aged 80 years and older, with a decrease in protection beyond 3 months of completing vaccination, and a further decrease after 5 months. We found no differences between periods with circulation of Alpha or Delta SARS‐CoV‐2 variants, although variant‐specific VE was slightly higher against Alpha.

Conclusions

The SiVIRA sentinel hospital surveillance network in Spain was able to describe clinical and epidemiological characteristics of SARI hospitalizations and provide estimates of COVID‐19 VE in the population under surveillance. Our estimates add to evidence of high effectiveness of mRNA vaccines against severe COVID‐19 and waning of protection with time since vaccination in those aged 80 or older. No substantial differences were observed between SARS‐CoV‐2 variants (Alpha vs. Delta).

Near real-time surveillance of the SARS-CoV-2 epidemic with incomplete data

When responding to infectious disease outbreaks, rapid and accurate estimation of the epidemic trajectory is critical. However, two common data collection problems affect the reliability of the epidemiological data in real time: missing information on the time of first symptoms, and retrospective revision of historical information, including right censoring. Here, we propose an approach to construct epidemic curves in near real time that addresses these two challenges by 1) imputation of dates of symptom onset for reported cases using a dynamically-estimated "backward" reporting delay conditional distribution, and 2) adjustment for right censoring using the NobBS software package to nowcast cases by date of symptom onset. This process allows us to obtain an approximation of the time-varying reproduction number (Rt) in real time. We apply this approach to characterize the early SARS-CoV-2 outbreak in two Spanish regions between March and April 2020. We evaluate how these real-time estimates compare with more complete epidemiological data that became available later. We explore the impact of the different assumptions on the estimates, and compare our estimates with those obtained from commonly used surveillance approaches. Our framework can help improve accuracy, quantify uncertainty, and evaluate frequently unstated assumptions when recovering the epidemic curves from limited data obtained from public health systems in other locations.

Near real-time surveillance of the SARS-CoV-2 epidemic with incomplete data

Designing public health responses to outbreaks requires close monitoring of population-level health indicators in real-time. Thus, an accurate estimation of the epidemic curve is critical. We propose an approach to reconstruct epidemic curves in near real time. We apply this approach to characterize the early SARS-CoV-2 outbreak in two Spanish regions between March and April 2020. We address two data collection problems that affected the reliability of the available real-time epidemiological data, namely, the frequent missing information documenting when a patient first experienced symptoms, and the frequent retrospective revision of historical information (including right censoring). This is done by using a novel back-calculating procedure based on imputing patients' dates of symptom onset from reported cases, according to a dynamically-estimated "backward" reporting delay conditional distribution, and adjusting for right censoring using an existing package, NobBS , to estimate in real time (nowcast) cases by date of symptom onset. This process allows us to obtain an approximation of the time-varying reproduction number ( R t ) in real-time. At each step, we evaluate how different assumptions affect the recovered epidemiological events and compare the proposed approach to the alternative procedure of merely using curves of case counts, by report day, to characterize the time-evolution of the outbreak. Finally, we assess how these real-time estimates compare with subsequently documented epidemiological information that is considered more reliable and complete that became available later in time. Our approach may help improve accuracy, quantify uncertainty, and evaluate frequently unstated assumptions when recovering the epidemic curves from limited data obtained from public health surveillance systems in other locations.

Characterization of the first autochthonous dengue outbreak in Spain (August-September 2018)

On October 3rd 2018, dengue virus (DENV) infection was confirmed in three family members (symptoms onset between August 18th and 27th) without travel history outside of Spain. They had been together in the Autonomous Communities (AC) of Murcia and Andalusia. By the end of October, a second cluster of two dengue cases (symptoms onset on September 27th and 30th) was confirmed in the AC of Murcia. DENV type 1 sequence was identical to the first cluster, and the epidemiological link was a visit from a case of the first cluster to a fruit-farm neighboring the small village of residence of the second cluster. The entomological investigation found Aedes albopictus activity in this area although all mosquitoes were PCR-negative for DENV. This is the first autochthonous dengue outbreak identified in Spain. This outbreak highlights challenges to timely detect and respond to DENV transmission and opens questions on dengue dynamics in a non-endemic context.

Absence of protective ethnic density effect on Ecuadorian migrants' mental health in a recent migration setting: a multilevel analysis

PURPOSE

We aimed to study the association between the Ecuadorians' ethnic density (EED) of the areas of residence (AR) with the mental health of Ecuadorians in Spain.

METHODS

Multilevel study of 568 Ecuadorian adults in 33 AR randomly selected from civil registries and interviewed at home. Possible psychiatric case (PPC) was measured by scoring ≥5 in General Health Questionnaire-28. Ecuadorians' ethnic density was dichotomized in high and low EED (<6 %). Multilevel logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals (CI).

RESULTS

Prevalence of PPC, 24 % (95 %CI 20-28 %), varied by area of residence. Ecuadorians' ethnic density varied by area of residence ranging from 0.9 to 19.5 %. PPC prevalence in High Ecuadorians' ethnic density AR was 29.5 and 20.4 % in low EED AR (p 0.013). Ecuadorians from High EED AR had higher odds of PPC than those from Low EED AR (OR 1.65 95 %CI 1.01-2.72). Adjusting for individual confounders (largely self-perceived discrimination), OR decreased to 1.48 (95 %CI 0.87-2.55). The final model, adjusted by area of residence and educational level, yielded an OR 1.37 (95 %CI 0.78-2.40).

CONCLUSIONS

No protective association between the Ecuadorians' ethnic density of the Area of residence and Ecuadorian migrants' mental health was found. Mechanisms underlying beneficial ethnic density effects may be absent in recent migration settings.

Mental health in Ecuadorian migrants from a population-based survey: the importance of social determinants and gender roles

PURPOSE

To describe the prevalence of and the risk factors for poor mental health in female and male Ecuadorian migrants in Spain compared to Spaniards.

METHOD

Population-based survey. Probabilistic sample was obtained from the council registries. Subjects were interviewed through home visits from September 2006 to January 2007. Possible psychiatric case (PPC) was measured as score of ≥5 on the General Health Questionnaire-28 and analyzed with logistic regression.

RESULTS

Of 1,122 subjects (50% Ecuadorians, and 50% women), PPC prevalence was higher in Ecuadorian (34%, 95% CI 29-40%) and Spanish women (24%, 95% CI 19-29%) compared to Ecuadorian (14%, 95% CI 10-18%) and Spanish men (12%, 95% CI 8-16%). Shared risk factors for PPC between Spanish and Ecuadorian women were: having children (OR 3.1, 95% CI 1.4-6.9), work dissatisfaction (OR 4.1, 95% CI 1.6-10.5), low salaries (OR 2.5, 95% CI 1.1-5.9), no economic support (OR 1.8, 95% CI 0.9-3.4), and no friends (OR 2.2, 95% CI 1.1-4.2). There was an effect modification between the nationality and educational level, having a confidant, and atmosphere at work. Higher education was inversely associated with PPC in Spanish women, but having university studies doubled the odds of being a PPC in Ecuadorians. Shared risk factors for PPC in Ecuadorian and Spanish men were: bad atmosphere at work (OR 2.4, 95% CI 1.3-4.4), no economic support (OR 3.5, 95% CI 1.3-9.5), no friends (OR 2.5, 95% CI 0.9-6.6), and low social support (OR 1.6, 95% CI 0.9-2.9), with effect modification between nationality and partner's emotional support.

CONCLUSIONS

Mental health in Spanish and Ecuadorian women living in Spain is poorer than men. Ecuadorian women are the most disadvantaged group in terms of prevalence of and risk factors for PPC.

Burden of disease related to hepatitis C and hepatitis B in Spain: a methodological challenge of an unfolding health problem

Most previous studies of burden of disease (BoD) in the area of transmissible diseases have assessed the burden of hepatitis C and B without including the end stages of the disease and using an incident approach. We aimed to assess the disability-adjusted life years (DALYs) related to hepatitis C and B in Spain in 2006 taking into account related cirrhosis and liver cancer. A prevalence approach was used to estimate current years lived with disability (YLD) because of viral hepatitis contracted years/decades before. We added years of life lost (YLL) to obtain DALYs. Around 76,000 DALYs were attributed to hepatitis C virus (HCV) and 15,323 to hepatitis B virus (HBV) when calculated without applying social values. Applying the discount rate and age-weighting used in the Global Burden Disease study, the BoD nearly halved. In any case, the burden related to hepatitis C including long-term outputs becomes the leading cause of DALYs among transmissible diseases in Spain. The mortality component (YLL) represents more than 90% of the BoD in both HCV and HBV. The findings emphasize the need to provide good surveillance systems not only concerning acute viral hepatitis, but also chronic and end-stage consequences to allow a reliable assessment of the prevention and public health control policies.

[Methodology and fieldwork logistics of a multilevel research study on the influence of neigbourdhood's characteristics on natives and Ecuadorian's mental health in Spain]

The methodological design, characteristics and fieldwork stage of a multilevel research study on the impact of the environmental characteristics on mental health in an autochthonous and immigrant population are described in this paper. Individual data were obtained using a core questionnaire 40 minutes length from home interviews of Spanish and Ecuadorian adults from September 2006 to January 2007. A random sample of 1186 people aged 18-55, with equal distribution of gender and nationality was obtained from Civil Registers of 33 areas (municipalities or neighbourhoods) of Madrid, Alicante, Almeria and Murcia, chosen by ethnic density and socioeconomic criteria. Previously, a pilot study was carried out. Socioeconomic indicators of neighbourhoods and selected communities were obtained from Municipal Registers and other secondary sources. Finally, 1144 people were interviewed (96%). Each person was contacted at home at two different times. The global response rate was 61%, higher among Ecuadorians (69%), who presented more problems of localisation (34%). Analyzing methods and fieldwork process the conclusion is that sample strategies for this type of population studies should be evaluated using feasibility criteria given time and money constraints, against the need to obtain representative samples of the target populations. There were serious shortcomings in the availability of social integration indicators at the neighbourhood level.

Discrimination and mental health in Ecuadorian immigrants in Spain

BACKGROUND

The aim of this study was to examine the effects of ethnic discrimination on the mental health of Ecuadorian immigrants in Spain and to assess the roles of material and social resources.

METHODS

Data were taken from the "Neighbourhood characteristics, immigration and mental health" survey conducted in 2006 in Spain. Psychological distress measured as "Possible Psychiatric Case" (PPC) was measured by the GHQ-28. A logistic regression was fitted to assess the association between PPC and discrimination. Interactions of discrimination with social and material resources were tested using product terms.

RESULTS

Some 28% of the participants met our definition of PPC. About 20% of those who reported no discrimination were PPCs, rising to 30% of those who sometimes felt discriminated against and 41% of those who continually perceived discrimination. The OR for continuous discrimination was 12 (95% CI 3.5 to 40.3) among those with high financial strain, and 10 (2.4 to 41.7) when there was lack of economic support. Emotional support had an independent effect on PPC (OR 1.8, 95% CI 1.0 to 3.6, for those who reported having no friends). Social integration through a community group or association was positively related to the probability of being a PPC (OR 1.7, 95% CI 1.0 to 2.9).

CONCLUSION

Ethnic discrimination is associated with psychological distress in these Ecuadorian immigrants in Spain. Discrimination effects may be exacerbated among those facing economic stress and those without economic support. These particularly vulnerable immigrants should be the subject of social and health interventions.

[Effect of weather temperature on hospital emergencies in the Region of Murcia, Spain, throughout the 2000-2005 and its use in epidemiological surveillance]

BACKGROUND

The effect of the weather temperature on mortality has been studied more in depth than its effect on morbidity. In Murcia, the number of daily emergencies and the cases of heat stroke for which care is provided at the hospitals in this Region have been studied.

OBJECTIVE

to evaluate the effect that the weather temperature has on the number of hospital emergencies and the use of these indicators for the surveillance of hot weather-related morbidity.

METHODS

The effect of the weather temperature on the number of summertime emergencies (2000-2005) has been studied by estimating the percentage increase in emergencies when the weather temperature thresholds established by the Ministry of Health and Consumer Affairs (Max. 38 degrees C and Min. 22.4 degrees C) are exceeded, and by each degree of temperature rise. Results have been stated as Relative Risk (RR) with a 95% CI. A comparison has been drawn between the heat strokes notified and the hospital admissions recorded in the Minimum Basic Data Set at Hospital Discharge (MBDS).

RESULTS

Within the 2000-2005 period, the number of emergencies rose by 1.6% on those days when the minimum temperature for the day was above 22.4 degrees C (RR: 1.016; 95% CI 1.0076-1.0244) and by 0.21% for each degree of rise in the minimum temperature for the day (RR: 1.0021, 95% CI 1.0000-1.0044). A total of 38% of the heat strokes admitted to hospital were not reported, of which 40% had occupational exposure.

CONCLUSIONS

The minimum temperature for the day could have a greater effect in Murcia than the maximum for the day. Based on the current thresholds, the number of emergencies/day does not seem to be a suitable indicator for monitoring the effect of the weather temperature, information on the diagnosis and the age being needed. Heat strokes provide partial information on the impact, but highlight less-considered population groups at risk.

Determinants of health system delay among confirmed tuberculosis cases in Spain

BACKGROUND

Health system delay (HSD) is an important issue in tuberculosis (TB) control. This report investigates HSD and associated factors in a cohort of Spanish culture-confirmed TB patients.

METHODS

Data were collected from clinical records. Using logistic regression with two different cut-off points to define HSD (median and 75th percentile), adjusted odds ratios were used to estimate the association between HSD and different variables.

RESULTS

A total of 5184 culture-confirmed TB cases were included. Median and 75th percentile HSD were 6 and 25 days respectively. HSD significantly greater than the median was associated with: age >44 years, past or present intravenous drug use, diagnosis at a primary-care centre, prior preventive therapy, positive histology, request for drug-sensitivity testing, presence of silicosis or neoplasia in addition to TB, presence of non-TB related symptoms, and gastrointestinal site. HSD greater than the 75th percentile was related to the same variables, with the exception of diagnosis at a primary-care centre, positive histology, silicosis, non-TB-related symptoms and gastrointestinal site, for which the association disappeared; in contrast, an association with female gender emerged.

CONCLUSION

Despite free health care being universally available in Spain, there are some groups of TB patients whose treatment is unduly delayed.

Prevalence of hepatitis A antibodies in southeastern Spain: a population-based study

The prevalence of hepatitis A antibodies in the adult population of the Murcia Region (southeast of Spain) was estimated using an anonymous unlinked serosurvey in a population-based sample of 2,203 adults. The overall anti-HAV prevalence was 76.5%. The prevalence increased with age and was higher in individuals living in towns with less than 10,000 inhabitants.