New data modeling shows the first infections in humans could have occurred as early as October 2019.
According to new data modeling, the first human cases of Sars-CoV-2 are likely to have occurred in China between about early October and mid-November 2019. This is confirmed by an analysis presented in the journal PLOS Pathogens. According to the calculation, a date around November 17 is likely, the researchers report. Accordingly, the virus is likely to have spread much faster in the world than known after the first detections.
The first officially confirmed infections with the novel pathogen had been recorded in early December 2019 in the central Chinese metropolis of Wuhan. However, experts have long assumed that the virus was already circulating in humans before that. This assumption had also expressed the investigation team of the World Health Organization (WHO), which had searched in January and February in China for the origin of the virus.
Worldwide spread probably as early as January 2020
Scientists led by David Roberts of the University of Kent in the United Kingdom calculated the most likely time frame for the pathogen to jump from animals to humans based on data for the first confirmed cases in China and abroad. They used a mathematical model that is used in the conservation field to make predictions about the extinction of species.
According to the model, the virus is likely to have spread worldwide by January. According to the scientists’ calculations, the first infections outside China could have occurred in Japan around January 3. The first case in Europe would have been according to their calculation in Spain around 12 January, the first in the USA around 16 January.
The scientists caution, however, that their conclusions “are only as good as the data that were used.” Factors such as the quality of the first available detection methods in each country are likely to have influenced the results, they say. In addition, many infections are asymptomatic – or with rather mild cold symptoms, with which people often did not see a doctor, especially at the beginning of the pandemic, and therefore were not tested.
Transmission to humans through intermediate host?
Exactly how Sars-CoV-2 was transmitted to humans remains unclear. The majority of experts worldwide assume that the virus was transmitted from bats to humans via an as yet unknown intermediate host – such as tanuki in fur farms. In US politics in particular, however, the possibility of an accidental or deliberate origin in the laboratory is repeatedly raised – much to China’s displeasure.
Whether the actual course of events can still be clarified is uncertain – experts had noted several times that no analyses from China have been published on this so far. It is unclear whether data is being kept under lock and key or whether it simply does not exist.
- source: kurier.at/picture: pixabay.com
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