Covid-19 one year on: the impossible search for Patient Zero

A study found the first cases were recorded on December 1, 2019, but the origins of the outbreak remain a mystery

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  Staff from the Wuhan Hygiene Emergency Response Team conduct searches on the closed Huanan Seafood Wholesale Market in the city of Wuhan at the start of the outbreak on January 11, 2020. AFP

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  A woman leaves the Wuhan Medical Treatment Centre, where a man who died from a respiratory illness was confined on January 12, 2020. A 61-year-old man is thought to be the first person to die. AFP

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  A woman wears a plastic water bottle with a cutout to cover her face, as she walks on a footbridge in Hong Kong on January 31, 2020, as a preventative measure following a virus outbreak which began in the Chinese city of Wuhan.. AFP

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  An empty Times Square is seen on the street following the outbreak of coronavirus in New York City, U.S., March 18, 2020. Reuters

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  A nurse wearing protective mask and gear comforts another as they change shifts on March 13, 2020 at the Cremona hospital, southeast of Milan. AFP

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  A woman takes part in an online pilates class at home in Nicosia, Cyprus, as restrictions on movement and social distancing were imposed across the island nation. AFP

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  A woman standing on her balcony, reaches out to catch a rose delivered to her via a drone on Mother's day, in the Lebanese coastal city of Jounieh, north of the capital Beirut on March 21, 2020. AFP

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  Police inspector Rajesh Babu, wearing a coronavirus-themed helmet, speaks to a family during a government-imposed nationwide lockdown on March 28, 2020. AFP

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  Healthcare workers wearing face masks and protective suits acknowledge applause outside the Hospital de Barcelona on April 13, 2020 in Barcelona, during a national lockdown. AFP

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  A racoon walks in a deserted Central Park in Manhattan on April 16, 2020 in New York City. Gone are the softball games, horse-drawn carriages and hordes of tourists. AFP

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  A woman in a mask walks past a mural of a hand on the side of a building in Midtown New York City April 22, 2020. AFP

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  View of the Intensive Care Unit at the Gilberto Novaes Hospital in Manaus, Brazil, on May 20, 2020. AFP

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  An Iraqi man in a hazmat suit takes pictures of a relative's tombstone at a cemetery for Covid-19 victims, 20 km from the central Iraqi holy city of Najaf, on June 10, 2020. AFP

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  Irish Paralympic hopeful Leo Hynes, who is blind, trains in his home-made training pool in his front garden at home in Tuam, Co Galway, west Ireland, on June 18, 2020. AFP

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  The Uceli Quartet perform for an audience made of plants during a concert created by Spanish artist Eugenio Ampudia and that will be later streamed to mark the reopening of the Liceu Grand Theatre in Barcelona on June 22, 2020 following a national lockdown. AFP

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  A lab technician operates a laser machine that tests rapid DPI blood tests at Dubai's Mina Rashid screening centre on August 26, 2020. Chris Whiteoak / The National

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  An Aymara indigenous woman wears a face mask as she offers cleaning products for sale at the Rodriguez Market in La Paz, Bolivia, on September 1, 2020, AFP

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  A worker disinfects footballs before the closed-door Copa Libertadores group phase football match between Colombia's Junior and Ecuador's Barcelona at the Roberto Melendez Stadium in Barranquilla, Colombia, on September 30, 2020. AFP

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  A patient infected with coronavirus lies in an intensive care room of the Estree Private Hospital in Stains, on the outskirts of Paris on November 12, 2020. AFP

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  A protestor holding a placard is spoken to by police officers as she attends an anti-vaccine demonstration outside the offices of the Bill and Melinda Gates Foundation in central London on November 24, 2020. AFP

The search for an effective vaccine against Covid-19 appears to have reached a breakthrough, but questions remain about when and where the virus that crippled the world started.

Working with China, the World Health Organisation this month has been given permission to send international experts to the country as part of the organisation's inquiry into the origins of the virus.

Ground zero is Wuhan, a city of more than 11 million people and a natural crossroads for transport, in central China on the banks of the Yangtze river.

The WHO-led investigation will look for answers to some questions that in reality may never be answered. Where did Covid-19 begin and who contracted it first? The so-called Patient Zero.

They are always here and something ignites them, maybe human density or environmental conditions

There were unconfirmed reports in Chinese media of a case on November 17, 2019, while the first reliable confirmation of cases was on December 1, 2019.

According to research by Chinese scientists published in The Lancet in late January, that date was when symptoms in the first 41 patients were recorded in a laboratory.

More details were given in a BBC Chinese Service report in February. After talking to doctors involved in the case, the possible first patient was identified as a man in his seventies, already suffering from Alzheimer's disease and "in very bad condition" when he was admitted to hospital, Dr Wu Wenjuan, director of the intensive care unit at Jinyintan Hospital in Wuhan told the BBC.

The man’s fate was not recorded, but the research is clear that he and his family had no connection with the Huanan Seafood Wholesale Market in Wuhan, often identified as a probable source of Covid-19, along with the theory that it crossed into humans from animals sold there.

The next three cases to show symptoms in Wuhan also had no obvious link to the market, Dr Wu Wenjuan said.

As it turned out, the old man lived some distance from the market, which he had not visited and, in any case, because of Alzheimer's disease, he never went outdoors. To deepen the mystery, none of his family developed Covid-19.

When asked by the BBC about where he had possibly become infected, Dr Wu Wenjuan avoided the question, saying only "what you asked is the direction of our next research".

Of the 41 Covid-19 cases admitted to hospital last December that formed The Lancet paper, 27 had direct exposure to the seafood market, including the first fatal case, a trader whose wife also contracted the disease even though she had not been to the market.

By January 2, 2020, six of those patients – or about 15 per cent – had died. Yet on January 8, the WHO tweeted that the outbreak had caused no deaths and said six days later that, according to China, there was “no clear evidence of human-to-human transmission".

It is discrepancies such as these that raised questions about the origins of Covid-19.

The BBC Chinese Service report was among the first to point the finger of suspicion at the Wuhan Institute of Virology, which faced claims that the disease may have been created there and escaped as a result of poor biosecurity.

This suggestion is strongly denied by China, while other international experts also defended the institute, noting there is no evidence the virus has been artificially modified.

In recent weeks, there was another twist.

More research claimed to have found traces of Covid-19 in Europe months before it was first reported in Wuhan.

An Italian study that later found antibodies to the virus in blood samples taken during a cancer survey last September has been quoted by Chinese authorities as evidence the virus may have several origins.

Other research detected Covid-19 in France on December 27 last year, while a study of wastewater at the University of Barcelona claimed it found traces of the virus in samples taken in March.

A woman in Hong Kong wears a plastic water bottle to cover her face in January. Mask and food shortages briefly gripped many countries at the start of the pandemic. AFP

These examples led Dr Tom Jefferson, of the Centre for Evidence-Based Medicine at the University of Oxford, to suggest the virus may have been dormant in many countries, simply emerging when the conditions were right.

"They are always here and something ignites them, maybe human density or environmental conditions, and this is what we should look for," Dr Jefferson told the Daily Telegraph in July.

Other experts have disputed the reliability of these tests, saying some are likely the result of laboratory cross contamination.

Only six out of 111 of the Italian samples had enough antibodies to kill Covid-19, while using the same test as a control on different blood samples known to contain viruses failed to detect any antibodies.

Part of the problem is that Covid-19 is frequently asymptomatic, meaning people could have carried the disease undetected before the first hospital cases were observed.

The current WHO inquiry states that its work is “not bound to any location and may evolve geographically as evidence is being generated, and hypotheses evolve".

A worker in a protective suit is seen at the closed seafood market in Wuhan in January. Reuters

But it will begin by looking at Wuhan and the now closed seafood market, which at the time sold a variety of farmed and wild animals.

“Research … has shown that a range of animals – including wild and farmed species – are susceptible to infection, but when and where Covid-19 spilled over to humans, and from which animal, remains unknown," the WHO reported on November 5.

It also found no trace of Covid-19 on any animal samples taken from the market but did find it in 69 of 842 environmental samples from drains and sewage on the site.

The WHO admits “very little is currently known about how, where and when the virus started circulation in Wuhan".

The route from a house-bound old man with Alzheimer's disease to 63 million cases worldwide and 1.47 million dead, so far, is no clearer than it was a year ago.