RESUMO
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.
RESUMO
Brief abstractImplementation of measures to limit the spread of the SARS-CoV-2 virus at the start of the COVID-19 pandemic resulted in a rapid decrease in all other respiratory pathogens. As COVID-19 containment measures were relaxed, the first non-COVID respiratory viruses to return to prepandemic levels were members of the rhinovirus/enterovirus, followed by the rapid return of seasonal coronaviruses, parainfluenza, and respiratory syncytial virus after the complete removal of COVID-19 precautions at the state level, including an end to mask mandates. Inasmuch as COVID-19 has dominated the landscape of respiratory infections since early 2020, it is important for clinicians to recognize the return of non-COVID respiratory pathogens may be rapid and significant when COVID-19 containment measures are removed.
RESUMO
Genetic variants of the SARS-CoV-2 virus are of substantial concern because they can detrimentally alter the pandemic course and disease features in individual patients. Here we report SARS-CoV-2 genome sequences from 12,476 patients in the Houston Methodist healthcare system diagnosed from January 1, 2021 through May 31, 2021. The SARS-CoV-2 variant designated U.K. B.1.1.7 increased rapidly and caused 63%-90% of all new cases in the Houston area in the latter half of May. Eleven of the 3,276 B.1.1.7 genomes had an E484K change in spike protein. Compared with non-B.1.1.7 patients, individuals with B.1.1.7 had a significantly lower cycle threshold value (a proxy for higher virus load) and significantly higher rate of hospitalization. Other variants (e.g., B.1.429, B.1.427, P.1, P.2, and R.1) also increased rapidly, although the magnitude was less than for B.1.1.7. We identified 22 patients infected with B.1.617 "India" variants; these patients had a high rate of hospitalization. Vaccine breakthrough cases (n=207) were caused by a heterogeneous array of virus genotypes, including many that are not variants of interest or concern. In the aggregate, our study delineates the trajectory of concerning SARS-CoV-2 variants circulating in a major metropolitan area, documents B.1.1.7 as the major cause of new cases in Houston, and heralds the arrival and spread of B.1.617 variants in the metroplex.
