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).

Age-Dependent Serotype-Associated Case-Fatality Rate in Invasive Pneumococcal Disease in the Autonomous Community of Madrid between 2007 and 2020.

The aim of this study was to investigate the serotype-associated fatality rate in cases of invasive pneumococcal disease (IPD) in the Spanish region of Madrid between 2007 and 2020. Serotyping was performed by Pneumotest Latex and the Quellung reaction using commercial antisera. Case-fatality rate was estimated as the ratio between the number of deaths at hospital discharge and the number of cases attributable to each serotype. To evaluate the association measures, the odds ratios with a 95% confidence interval were calculated. Twenty five pneumococcal serotypes were associated to mortality and comprised 87.8% of the total number of isolates characterized. Serotypes 8, 3, 19A, 1, 7F, 22F, 12F, and 11A were the most prevalent (≥3% each). Serotypes 31, 11A, and 19F were significantly associated to high case-fatality rates (>20% each). The lower significantly associated case-fatality rate (<10% each) was found in serotypes 5, 1, 12B, 7F, 12F, 8, 33, and 10A. The serotypes with higher mortality levels (≥0.04 per 100,000 population) were 11A (fatality 24.0%), 3 (fatality 18.7%), 19A (fatality 12.5%), and 8 (fatality 7.2%). Serotype 3 was worrisome because it is associated with important fatality levels combined with very high incidence and mortality rates. Serotype 11A also showed a high fatality with marked incidence and mortality levels. Some few frequent serotypes as 31, 19F, and 15A despite its high fatality had low levels of mortality. By contrast other serotypes as 8 showing low fatality had high mortality ranges because it shows a wide extended distribution. Finally, common serotypes, such as 1 and 5, presented small mortality length, due to their low case-fatality rates.