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Sobre

Sobre

Em termos de temas de investigação principais destaca-se a gestão de dados em modelos de coerência fraca, mecanismos de agregação de dados e causalidade em sistemas distribuídos. No últimos anos, e em colaboração outros investigadores, têm sido desenvolvidos mecanismos de sumarização de dados como os Scalable Bloom Filters, registo de causalidade em ambientes dinâmicos com Interval Tree Clocks e Dotted Version Vectors, bem como abordagens robustas para o suporte à alta disponibilidade com coerência fraca via Conflict-Free Replicated Data Types. Alguns destes mecanismos têm sido aplicados na base de dados distribuída Riak e no Akka distributed data, estando estes mesmos em uso em diversas aplicações finais com milhões de utilizadores a nível global.

Tópicos
de interesse
Detalhes

Detalhes

  • Nome

    Carlos Baquero
  • Cluster

    Informática
  • Cargo

    Responsável de Área
  • Desde

    01 novembro 2011
003
Publicações

2023

Using survey data to estimate the impact of the omicron variant on vaccine efficacy against COVID-19 infection

Autores
Rufino, J; Baquero, C; Frey, D; Glorioso, CA; Ortega, A; Rescic, N; Roberts, JC; Lillo, RE; Menezes, R; Champati, JP; Anta, AF;

Publicação
SCIENTIFIC REPORTS

Abstract
Symptoms-based detection of SARS-CoV-2 infection is not a substitute for precise diagnostic tests but can provide insight into the likely level of infection in a given population. This study uses symptoms data collected in the Global COVID-19 Trends and Impact Surveys (UMD Global CTIS), and data on variants sequencing from GISAID. This work, conducted in January of 2022 during the emergence of the Omicron variant (subvariant BA.1), aims to improve the quality of infection detection from the available symptoms and to use the resulting estimates of infection levels to assess the changes in vaccine efficacy during a change of dominant variant; from the Delta dominant to the Omicron dominant period. Our approach produced a new symptoms-based classifier, Random Forest, that was compared to a ground-truth subset of cases with known diagnostic test status. This classifier was compared with other competing classifiers and shown to exhibit an increased performance with respect to the ground-truth data. Using the Random Forest classifier, and knowing the vaccination status of the subjects, we then proceeded to analyse the evolution of vaccine efficacy towards infection during different periods, geographies and dominant variants. In South Africa, where the first significant wave of Omicron occurred, a significant reduction of vaccine efficacy is observed from August-September 2021 to December 2021. For instance, the efficacy drops from 0.81 to 0.30 for those vaccinated with 2 doses (of Pfizer/BioNTech), and from 0.51 to 0.09 for those vaccinated with one dose (of Pfizer/BioNTech or Johnson & Johnson). We also extended the study to other countries in which Omicron has been detected, comparing the situation in October 2021 (before Omicron) with that of December 2021. While the reduction measured is smaller than in South Africa, we still found, for instance, an average drop in vaccine efficacy from 0.53 to 0.45 among those vaccinated with two doses. Moreover, we found a significant negative (Pearson) correlation of around - 0.6 between the measured prevalence of Omicron in several countries and the vaccine efficacy in those same countries. This prediction, in January of 2022, of the decreased vaccine efficacy towards Omicron is in line with the subsequent increase of Omicron infections in the first half of 2022.

2023

Using survey data to estimate the impact of the omicron variant on vaccine efficacy against COVID-19 infection

Autores
Rufino, J; Baquero, C; Frey, D; Glorioso, CA; Ortega, A; rešcic, N; Roberts, JC; Lillo, RE; Menezes, R; Champati, JP; Fernández Anta, A;

Publicação
Scientific Reports

Abstract
Symptoms-based detection of SARS-CoV-2 infection is not a substitute for precise diagnostic tests but can provide insight into the likely level of infection in a given population. This study uses symptoms data collected in the Global COVID-19 Trends and Impact Surveys (UMD Global CTIS), and data on variants sequencing from GISAID. This work, conducted in January of 2022 during the emergence of the Omicron variant (subvariant BA.1), aims to improve the quality of infection detection from the available symptoms and to use the resulting estimates of infection levels to assess the changes in vaccine efficacy during a change of dominant variant; from the Delta dominant to the Omicron dominant period. Our approach produced a new symptoms-based classifier, Random Forest, that was compared to a ground-truth subset of cases with known diagnostic test status. This classifier was compared with other competing classifiers and shown to exhibit an increased performance with respect to the ground-truth data. Using the Random Forest classifier, and knowing the vaccination status of the subjects, we then proceeded to analyse the evolution of vaccine efficacy towards infection during different periods, geographies and dominant variants. In South Africa, where the first significant wave of Omicron occurred, a significant reduction of vaccine efficacy is observed from August-September 2021 to December 2021. For instance, the efficacy drops from 0.81 to 0.30 for those vaccinated with 2 doses (of Pfizer/BioNTech), and from 0.51 to 0.09 for those vaccinated with one dose (of Pfizer/BioNTech or Johnson & Johnson). We also extended the study to other countries in which Omicron has been detected, comparing the situation in October 2021 (before Omicron) with that of December 2021. While the reduction measured is smaller than in South Africa, we still found, for instance, an average drop in vaccine efficacy from 0.53 to 0.45 among those vaccinated with two doses. Moreover, we found a significant negative (Pearson) correlation of around - 0.6 between the measured prevalence of Omicron in several countries and the vaccine efficacy in those same countries. This prediction, in January of 2022, of the decreased vaccine efficacy towards Omicron is in line with the subsequent increase of Omicron infections in the first half of 2022. © 2023, The Author(s).

2023

What Ever Happened to Peer-to-Peer Systems?

Autores
Baquero, C;

Publicação
Commun. ACM

Abstract
[No abstract available]

2023

Time-limited Bloom Filter

Autores
Rodrigues, A; Shtul, A; Baquero, C; Almeida, PS;

Publicação
Proceedings of the 38th ACM/SIGAPP Symposium on Applied Computing, SAC 2023, Tallinn, Estonia, March 27-31, 2023

Abstract

2023

Time-limited Bloom Filter

Autores
Rodrigues, A; Shtul, A; Baquero, C; Almeida, PS;

Publicação
CoRR

Abstract

Teses
supervisionadas

2022

Development of a platform for integrated clinical records of cystic fibrosis patients in a national reference center

Autor
Márcia Isabel Reis Teixeira

Instituição
UP-FEUP

2022

Design de Interface para uma Plataforma de Registo Clínico Integrado de Doentes com Fibrose Quística num Centro de Referência Nacional

Autor
Maria Teresa Santos Quelhas Pinto Leite

Instituição
UP-FEUP

2022

Planet-Scale Leaderless Consensus

Autor
Vítor Manuel Enes Duarte

Instituição
UM

2022

Optimizing Operation-based Conflict-Free Replicated Data Types

Autor
Georges Younes

Instituição
UM

2021

Bloom filters for stream windows

Autor
Ana Catarina Gomes Rodrigues

Instituição
UM