Coronavirus infecting people ‘weeks earlier than thought’

New research makes the case coronavirus began circulating around the world well before the first reported Chinese cases in January and February.

Molecular biologist William Dundon runs a test to detect whether a person has been infected with COVID-19, at the IAEA's Laboratories in Seibersdorf, Austria. Picture: AFP

Scientists have begun narrowing down how the coronavirus is spreading, and also pinpointing when it first began transmission around the world — and it’s earlier than first thought.

University College London’s Genetics Institute have screened the genomes of more than 7500 viruses from infected patients around the world.

“Phylogenetic estimates support that the COVID-2 pandemic started sometime around October 6, 2019 to December 11, 2019, which corresponds to the time of the host jump into humans,” lead researcher Francois Balloux said.

Researchers say people were getting infected around the world at least weeks, if not months, before the first reported Chinese cases in January and February. The genetic code of the virus was first released by Chinese researchers on January 5.

Prof Balloux’s study also found almost 200 recurrent genetic mutations of the new coronavirus — SARS-CoV-2 — but dispelled suggestions there were three different strains of the virus around the world.

I've seen many alarmist and incorrect claims about mutations in #SARSCoV2 . In this thread I will address some of the major misconceptions. Parts of the material I cover can be found expressed more formally in an article we published recently. https://t.co/p4BDOTmuFM.
(1/11) pic.twitter.com/qMUh1bAXbV

— Prof Francois Balloux (@BallouxFrancois) May 9, 2020

In a tweet on Saturday Professor Balloux said: “There are no ‘S’, ‘G’, ‘European’, ‘American’ or whatnot #SARSCoV2 lineages. All such classifications are arbitrary and largely meaningless. Two random #SARSCoV2 genomes in circulation today are less than 10 mutations apart. This is a ‘largely clonal population’ at this stage.”

He added: “The mutation rate of #SARSCoV2 is largely unremarkable for an RNA virus and has been estimated to ~18 mutations/genome/year. A strain in circulation today is on average ~10 mutations away from its ancestor that jumped into humans in Oct/Nov 2019.”

Anecdotally in the UK there appeared to be many people struck down with mystery fevers in mid to late December.

Two of my family members, living hundreds of kilometres apart from each other, were so sick with fever they attended hospital.

One, who fell ill in mid December having just returned from Saudi Arabia, had blood tests at the local hospital after suffering six days of fever and started to develop a rash on his extremities and face. He was told he had a mystery virus and he then had headaches for a fortnight that were so severe it prompted another rare visit to the doctor.

The other was sick throughout Christmas and had chest X-rays and was diagnosed with a form of pneumonia. Again it’s uncertain if these cases were coronavirus or an unusual flu-like illness.

But when British journalist Allison Pearson tweeted that she believed the virus may have been around before January she was inundated with hundreds of people believing they may have already had the virus, having suffered unusual fevers and pneumonia.

The South China Morning Post reported in mid-March that the earliest known case was a 55-year-old man from Hubei Province diagnosed on November 17, and said China had 60 confirmed cases by December 20.

A study by French scientists published last week found a man in France was infected with COVID-19 as early as December 27, which was weeks before French health authorities confirmed the country’s first case.

The World Health Organisation said the French finding was “not surprising” and countries have been urged to re-test unusual samples taken from patients in late 2019.

Meanwhile Dr Muge Cevik, a virologist from the University of St Andrews, said a tranche of studies that have traced close contacts of confirmed coronavirus cases have shown transmission is highest among close family members, with the risk factors being homes, transport and indoor settings where people congregate.

She noted that susceptibility to contract the virus increased with age, as older people within households had a much higher infection rate than children.

She believes that close and prolonged contact is needed for the virus to transmit and so the risk is highest in enclosed environments.

Outdoor transmission is believed to be very low — below five per cent. Casual and short interactions are not the main driver of transmission, nor is contact with children, raising question marks about the UK’s insistence on having a 2m social distancing rule.