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. 2022 Nov;16(6):1014-1025.
doi: 10.1111/irv.13026. Epub 2022 Jul 26.

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

Clara Mazagatos  1   2 , Concepción Delgado-Sanz  1   2 , Susana Monge  1   3 , Francisco Pozo  2   4 , Jesús Oliva  1   2 , Virginia Sandonis  4 , Ana Gandarillas  5 , Carmen Quiñones-Rubio  6 , Cristina Ruiz-Sopeña  7 , Virtudes Gallardo-García  8 , Luca Basile  9 , María Isabel Barranco-Boada  10 , Olga Hidalgo-Pardo  11 , Olalla Vazquez-Cancela  12 , Miriam García-Vázquez  13 , Amelia Fernández-Sierra  14 , Ana Milagro-Beamonte  15   16 , María Ordobás  5 , Eva Martínez-Ochoa  6 , Socorro Fernández-Arribas  7 , Nicola Lorusso  8 , Ana Martínez  2   9 , Ana García-Fulgueiras  2   10 , Bartolomé Sastre-Palou  11 , Isabel Losada-Castillo  17 , Silvia Martínez-Cuenca  13 , Mar Rodríguez-Del Águila  14 , Miriam Latorre  15   16 , Amparo Larrauri  1   2 ; SARI surveillance VE group in Spain
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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

Clara Mazagatos et al. Influenza Other Respir Viruses. 2022 Nov.

Abstract

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).

Keywords: COVID-19; COVID-19 vaccine; SARI surveillance; SARS-CoV-2; Spain; test-negative design; vaccine effectiveness.

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Conflict of interest statement

The authors report no conflict of interest.

Figures

FIGURE 1
FIGURE 1
Flowchart for SARI patient inclusion in the VE study, Spanish SARI sentinel surveillance, Weeks 1–39/2021
FIGURE 2
FIGURE 2
Number of SARI COVID‐19 cases and negative controls by week of swab and number of SARI vaccinated by week of complete vaccination, Spanish SARI sentinel surveillance, Weeks 1–39/2021
FIGURE 3
FIGURE 3
COVID‐19 VE against SARI hospitalization confirmed with COVID‐19, by (A) age group, (B) vaccine type, and (C) time since vaccination, Spanish SARI sentinel surveillance, Weeks 1–39/2021
See this image and copyright information in PMC

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