Community transmission is responsible for the spread of the virus earlier this year in Wuhuan, the origin of the pandemic, according to a new study.
Researchers from the Wuhan Centers for Disease Control & Prevention and University of Illinois reported that a re-analysis of throat swabs from patients in Wuhan with flu-like symptoms found that some patients were positive for COVID-19, suggested the transmission of the virus community in Wuhan in early January 2020.
The COVID-19 pandemic is caused by the SARS-CoV-2 virus.
Although SARS-CoV-2 shares 80% of the same cell sequence and receptor identity as the SARS coronavirus that caused the epidemic in 2003, the clinical results of SARS-CoV-2 not only include viral pneumonia like SARS, but also cause milder disease. , the researchers noted.
Some people also present with asymptomatic infections – analysis by the Chinese CDC shows that 80% of confirmed COVID-19 cases are marked as mild or moderate type, without difficulty breathing or hypoxia, they added.
The first cases of COVID-19 were reported in Wuhan in December 2019. The rapid increase in reported cases shows that the transmission of the SARS-CoV-2 community was established in Wuhan and surrounding areas by the end of January 2020. Due to the use of diagnostic tests Molecular fast is not widespread before January 23, it is difficult to monitor SARS-CoV-2 transmission throughout the community, the researchers said.
To better understand how the disease spreads in Wuhan, they retrospectively investigated the presence of SARS-CoV-2 among local patients with flu symptoms, which are defined as outpatients with fever attacks of more than 100 degrees Fahrenheit, which suddenly appeared. cough, or sore throat.
They re-analyzed 640 throat swabs collected from these patients between 6 October 2019 and 21 January 2020. This time period coincided with the peak winter influenza and other respiratory ailments.
They note that the number of patients with flu symptoms in all age groups has increased dramatically, starting in early December and reaching a peak in the New Year. In particular, cases in groups of 5 to 14 years increased more than 24-fold during this period. Furthermore, flu-like symptoms data for the winter of 2019-2020 were significantly higher compared to previous years, indicating the need to distinguish between patients infected with influenza and those suspected of COVID-19.
In a re-analysis of the throat swab, the researchers found that nine out of 640 were, in fact, infected with SARS-CoV-2. The earliest start date for the case was January 4, one week after the outbreak was reported by the hospital.
“Despite the small weekly sample size, it seems that COVID-19 gradually developed among cases of flu-like illness during January,” the authors wrote. “In the last week of observation, the frequency of positive cases of SARS-CoV-2 has exceeded influenza virus among groups of patients older than 30 years. These findings are consistent with recent epidemiological estimates of the dynamics of early transmission of SARS-CoV-2. “
Interestingly, they added, the nine patients came from six different districts in the Wuhan metropolitan area and beyond, providing additional evidence for community transmission in the region.
This story first appearance in the publication of our sister, Genomeweb.