Details

Autor(en) / Beteiligte

• Kislaya, Irina
• Rodrigues, Eduardo Freire
• Borges, Vítor
• Gomes, João P
• Sousa, Carlos
• Almeida, José P
• Peralta-Santos, André
• Nunes, Baltazar

Titel

Comparative Effectiveness of Coronavirus Vaccine in Preventing Breakthrough Infections among Vaccinated Persons Infected with Delta and Alpha Variants

Ist Teil von

• Emerging infectious diseases, 2022-02, Vol.28 (2), p.331-337

Ort / Verlag

United States: U.S. National Center for Infectious Diseases

Erscheinungsjahr

2022

Quelle

MEDLINE

Beschreibungen/Notizen

• We developed a case-case study to compare mRNA vaccine effectiveness against Delta versus Alpha coronavirus variants. We used data on 2,097 case-patients with PCR-positive severe acute respiratory syndrome coronavirus 2 infections reported in Portugal during May-July 2021. We estimated the odds of vaccine breakthrough infection in Delta-infected versus Alpha-infected patients by using conditional logistic regression adjusted for age group and sex and matched by the week of diagnosis. We compared reverse-transcription PCR cycle threshold values by vaccination status and variant as an indirect measure of viral load. We found significantly higher odds of vaccine breakthrough infection in Delta-infected patients than in Alpha-infected patients (odds ratio 1.96 [95% CI 1.22-3.14]), suggesting lower effectiveness of the mRNA vaccines in preventing infection with the Delta variant. We estimated lower mean cycle threshold values for the Delta cases (mean difference -2.10 [95% CI -2.74 to -1.47]), suggesting higher infectiousness than the Alpha variant.