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Delta variants of SARS-CoV-2 cause significantly increased vaccine breakthrough COVID-19 cases in Houston, Texas
Preprint
in English
| medRxiv
| ID: ppmedrxiv-21260808
Journal article
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A scientific journal published article is available and is probably based on this preprint. It has been identified through a machine matching algorithm, human confirmation is still pending.
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ABSTRACT
Genetic variants of SARS-CoV-2 have repeatedly altered the course of the COVID-19 pandemic. Delta variants of concern are now the focus of intense international attention because they are causing widespread COVID-19 disease globally and are associated with vaccine breakthrough cases. We sequenced the genomes of 16,965 SARS-CoV-2 from samples acquired March 15, 2021 through September 20, 2021 in the Houston Methodist hospital system. This sample represents 91% of all Methodist system COVID-19 patients during the study period. Delta variants increased rapidly from late April onward to cause 99.9% of all COVID-19 cases and spread throughout the Houston metroplex. Compared to all other variants combined, Delta caused a significantly higher rate of vaccine breakthrough cases (23.7% for Delta compared to 6.6% for all other variants combined). Importantly, significantly fewer fully vaccinated individuals required hospitalization. Individuals with vaccine breakthrough cases caused by Delta had a low median PCR cycle threshold (Ct) value (a proxy for high virus load). This value was closely similar to the median Ct value for unvaccinated patients with COVID-19 caused by Delta variants, suggesting that fully vaccinated individuals can transmit SARS-CoV-2 to others. Patients infected with Alpha and Delta variants had several significant differences. Our integrated analysis emphasizes that vaccines used in the United States are highly effective in decreasing severe COVID-19 disease, hospitalizations, and deaths.
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Full text:
Available
Collection:
Preprints
Database:
medRxiv
Type of study:
Prognostic study
Language:
English
Year:
2021
Document type:
Preprint