The hypothesis that COVID-19 leaked accidentally from a Chinese lab in Wuhan was widely dismissed then as an unfounded conspiracy against China. The leak theory, which says that the virus was man-made in a lab, has again come to light as the researchers could not find the viral host that kicked off the pandemic.
After SARS-1 and MERS outbreaks in 2003 and 2012 respectively, studies proved that the virus was found in animals. Hence affected people were hit by Coronavirus that mutated in the host animal. Within months of the SARS-1 and MERS outbreaks, scientists found that animals had hosted the viruses before they could jump to humans. A few months after both outbreaks, scientists found that more than 80 percent of the animals around local markets were infected with the coronavirus. This proved that both SARS-1 and MERS outbreaks are infections that are transmitted from animals to humans.
After the SARS-CoV-2 outbreak, the World Health Organization (WHO) investigation team analysed more than 9,000 hospital samples collected from late 2019—the period before the epidemic started—and found no evidence of pre-pandemic infections. The study of people having Covid-like symptoms in China’s Hubei and Shaanxi provinces proved there were no instances of community infection. WHO team after testing more than 80,000 animals from 209 species in 2020, found no trace of SARS-CoV-2. So from where did the novel coronavirus suddenly come?
The testing conducted among wild, domesticated, and market animals hinted at the possibility of lab-leak theory.
A coronavirus adapts for the animals before it can spill over to humans and it takes time to optimize itself so that it can infect humans. But the process takes little time in a laboratory-made pathogen using humanised mice.