KUALA LUMPUR, Feb 3 — The novel coronavirus could have originated outside China, an international zoonotic disease expert said, as immune responses and the virus were discovered in Italy, Singapore and Spain before the Wuhan outbreak.
During the International AIDS Society (IAS) Covid-19 Conference: Prevention, Linfa Wang, director of the Programme in Emerging Infectious Diseases at Duke-NUS Medical School, Singapore, said there could be a possibility that SARS-CoV-2, the virus which causes Covid-19, may have originated far away from the initial outbreak site in Wuhan.
Wang shared how there was already evidence of the presence of the SARS-CoV-2 infection in humans before December 2019, when the world’s first Covid-19 outbreak was reported in the central Chinese city of Wuhan.
In September 2019 in Italy, there were antibodies found in humans against the Covid-19 virus, and in March 2019, when the polymerase chain reaction method was used to test the sewage water in Spain, the SARS-CoV-2 virus was found.
“Here are two papers, one from Singapore. Studied specific T cell response to SARS-Cov-2 and we found that before 2019, we already have people with T cell immunity to the virus,” Wang told the panel.
According to Wang, the ancestral virus of Covid-19 is from bats, which was quickly identified five days after the Wuhan outbreak, but the intermediate host that transmits the virus from animal to human is still unknown.
“So, there was a lot of mention about the Huanan Seafood Market in Wuhan. What we see is that in this market, you have a menu, they sold everything,” Wang said during his topic on ‘The origin of SARS-CoV2: Bats, pangolins, rodents or more?’
“We know that the early stage of the infection never had contact in this market. So, the new hypothesis is that this market could be the site of (a) spill back. Basically, humans brought the virus to Wuhan, to the market, and that had animal transmission and that spilled over to humans.”
Wang however said it’s not too late to investigate the origins of the virus but it takes an international and apolitical collaboration.
Early SARS-CoV-2 Antibodies Profile Can Predict Disease Outcome
Harvard virology expert Galit Alter, during her session at the IAS Covid-19 conference, shared studies that found that overall antibodies are not necessarily a predictor of Covid-19 outcome, whether a patient goes into convalescence (or recuperation), or dies.
In fact, the S-IgG response (a type of antibody) has a difference in the levels of those who survive or die from Covid-19.
“Evolution of spike specific IgG responses that are highly elevated at the time of symptom onsets already in individuals who go on to survive the disease,” Alter said.
“This response had to catch up in individuals who went on to ultimately pass away. They came up low and they never evolved in the same levels,” Alter added, referring to the S-IgG response in patients who died.
Hence, Alter said that the antibody profile can predict disease outcome as other subtypes of antibodies, such as IgA and IgM, have no difference in trajectory levels in those who die or go into convalescence.