The World Health Organization (WHO) continues its investigation into the origins of the SARS-CoV-2 virus, which led to the COVID-19 pandemic. Despite three years of research, the exact cause remains unclear. WHO Director-General Tedros Adhanom Ghebreyesus stated that all theories, including the possibility of zoonotic spillover from animals and a lab leak, are still being considered.
A recent report from the Scientific Advisory Group for the Origins of Novel Pathogens (SAGO) supports the idea that the virus likely jumped from animals to humans, possibly from bats or another intermediate host. However, the report emphasizes that SAGO cannot determine when, where, or how the virus first infected humans. The closest known related strains have been found in bats in China and Laos, but they are too distantly related to be the direct source of the outbreak.
One significant challenge in pinpointing the virus’s origins has been the lack of information from China. The WHO had requested genetic sequences from COVID-19 patients and details about animals sold in Wuhan markets, along with data on laboratory safety conditions. Unfortunately, China has not shared this information, which complicates the investigation into the lab leak theory.
Marietjie Venter, chair of SAGO, mentioned that without this crucial data, the lab leak hypothesis could not be thoroughly investigated or dismissed. She noted that this theory is often based more on political views than scientific evidence. The report also outlines two other hypotheses: one suggests the virus could have entered animal markets via cold chain processes, while the other involves the possibility of deliberate manipulation in a lab, which remains unsupported by evidence.
The report highlights that all four hypotheses will be reassessed if new information emerges, but the zoonotic spillover theory is currently the most supported. Ghebreyesus acknowledged the difficulties in the investigation and expressed concern about China’s lack of cooperation, urging the country to provide the necessary data.
Last year, reports indicated that China had stalled efforts to trace the virus’s origins in the early days of the outbreak, and the WHO may have missed opportunities to investigate the pandemic’s beginnings. Chinese officials have consistently rejected the idea that the virus originated from a lab, suggesting instead that investigations should focus on other countries.
As the investigation continues, researchers are narrowing down potential animal hosts that may have transmitted the virus to humans, including raccoon dogs and civet cats. Until more scientific data is available, the origins of SARS-CoV-2 will remain a mystery.