If you thought Covid-19 was the last pandemic to ravage the world, there may be some bad news in store for you. A study emphasising the ongoing pandemic threat from spill-over events has revealed that hundreds of thousands of people may be infected annually by animals carrying coronaviruses related to the one that causes Covid-19 each year in China and Southeast Asia.
Researchers with the EcoHealth Alliance and Singapore’s Duke-NUS Medical School said in a study released before peer review and publication that an average of 400,000 such infections occur annually, most going unrecognised because they cause mild or no symptoms and aren’t easily transmitted between people. Still, each spill-over represents an opportunity for viral adaptation that could lead to a Covid-like outbreak, they were quoted as saying by Bloomberg.
The Covid Origin Story
The risks bring us back to the oft-contested question: from where did the virus which causes Covid emerge? According to a research supported by US National Institute of Allergy and Infectious Diseases, bats are the main host-animals for viruses like SARS-CoV-2 and that people living near their roosts are especially vulnerable — a hypothesis which also led many to pin the blame on the Wuhan Institute of Virology for the "lab leak" of the virus.
Almost two dozen bat species that can be infected by coronaviruses dwell in an area of Asia more than six times the size of Texas, with southern China and parts of Myanmar, Laos, Vietnam and Indonesia deemed the riskiest for spillovers. Peter Daszak and colleagues at the New York-based EcoHealth Alliance used bat distribution modeling and ecological and epidemiological data to estimate the risk of exposure to SARS-related coronaviruses, and the rate of unreported bat-to-human infections in China, South Asia and Southeast Asia.
“Given the challenges of identifying the origins of Covid-19 and pathways by which SARS-CoV-2 spilled over to people, this approach may also aid efforts to identify the geographic sites where spill-over first occurred,” they said in the study.
Factoring-in all the possible 'intermediate' animal species, not just bats, could reveal how high the risk of exposure is. These include mink, civets, raccoon dogs, and other mammals commonly farmed and traded for food and fur in Asia, according to the research. It said 14 million people were employed in wildlife farming in China alone in 2016 — an industry worth $77 billion annually. In Asia, about 478 million people live in an area inhabited by coronavirus-carrying bats, covering most of Laos, Cambodia, Thailand, Vietnam, Nepal, Bhutan, peninsular Malaysia, Myanmar, southeast China, and the western islands of Indonesia, the study said.
What does the WHO say?
A special envoy to World Health Organisation (WHO) has said variants that can evade Covid vaccines are increasingly likely as many parts of the world remain unprotected, and that rich countries must wait for others to catch up before they start administering booster doses, according to a report by Bloomberg.
Dr Mike Ryan, executive director of WHO's Health Emergencies Program, said at a press briefing: "I think this virus is here to stay with us and it will evolve like influenza pandemic viruses, it will evolve to become one of the other viruses that affects us."
Officials at the global health agency have previously said vaccines do not guarantee the world would eradicate Covid-19 like it has other viruses. Several leading health experts, including White House chief medical advisor Dr. Anthony Fauci and Stephane Bancel, CEO of Covid vaccine maker Moderna, have warned that the world will have to live with Covid forever, much like influenza.
If the world had taken early steps to stop the spread of the virus, the situation today could have been very different, WHO officials said. "We had a chance in the beginning of this pandemic," Maria Van Kerkhove, the WHO's technical lead on Covid-19, said. "This pandemic did not need to be this bad."
So, covid to become endemic?
An endemic is a disease that is consistently present but limited to a particular area. This means that the disease spread and rate of illness is predictable, according to Columbia University's Mailman School of Public Health. An example of an endemic virus in the US that remains in the population at a low frequency is the seasonal flu. According to WHO's Chief Scientist Dr Soumya Swaminathan, the endemic stage is when a population learns to live with a virus. It's very different from the epidemic stage when the virus overwhelms a population.
Endemic diseases, like chicken pox or malaria, are not novel, and the rates of infection within a given population are fairly predictable. The Centers for Disease Control and Prevention (CDC) says that endemic "refers to the constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area."