A much-anticipated inquiry into the origins of the coronavirus pandemic wrapped up its mission in China on Tuesday with no breakthrough discovery, as investigators ruled out a theory that Covid-19 came from a lab but failed to identify which animal may have passed it to humans.

While the coronavirus likely jumped to humans from animals, it is still unclear which species first transmitted it, said Liang Wannian, who headed up the Chinese contingent of an inquiry carried out jointly with World Health Organization (WHO) experts.

The WHO mission -- which China repeatedly delayed -- was dogged by fears of a whitewash, with the US demanding a "robust" probe into the origins of the pandemic in late 2019, and China firing back with a warning not to "politicise" the investigation.

During the closely monitored mission -- which included a visit to a propaganda exhibition celebrating China's recovery -- reporters were largely kept at arms' length from the experts.

Liang, supported by WHO expert Ben Embarek, said there was "no indication" the sickness was circulating in Wuhan before December 2019 when the first official cases were recorded.

Embarek, who said identifying the virus' pathway from animals to humans remains a "work in progress", also scotched a controversial theory that the virus had leaked from a lab, calling it "extremely unlikely".

"Martyrdom' of health workers"

As investigators have struggled to pinpoint the origins of a virus that has now killed more than 2.3 million people, governments are continuing to grapple with its daily consequences.

Vaccination campaigns are gaining pace worldwide, with Iran the latest country to begin its rollout of Russia's Sputnik V jab.

Iran's President Hassan Rouhani said the vaccination was being carried out in "memory of the martyrdom of health workers", as medics at Tehran's Imam Khomeini hospital received the first shots.

Iran is also expected to receive 4.2 million doses of the AstraZeneca-Oxford vaccines under the Covax scheme, which intends to ensure jabs are distributed across the world and not hoarded by richer nations.

The AstraZeneca vaccine makes up the bulk of initial Covax deliveries to some 145 countries but it suffered a setback in recent days with a trial showing it only offers minimal protection against the coronavirus variant first detected in South Africa.

The results forced South Africa to delay the start of its vaccinations, but the WHO insisted Monday that the AstraZeneca shot remained vital to the global fight against Covid-19.

Richard Hatchett, head of the Coalition for Epidemic Preparedness Innovations (CEPI), said it was "vastly too early to be dismissing this vaccine".

"It is absolutely crucial to use the tools that we have as effectively as we possibly can," he told a WHO press briefing.

AstraZeneca has stood by its vaccine, and said researchers are working on an updated version that can be effective against the new variants. WHO authorisation for the shot is expected next week.

"Let's get used to it"

Despite the vaccine rollouts, life is far from back to normal for most people.

The pandemic and associated restrictions have crushed entire sectors of the global economy, laid waste to sports and cultural calendars and confined hundreds of millions to their homes.

In France, a row is brewing over restrictions on cultural institutions, with one local mayor allowing museums to reopen despite a nationwide ban.

"There is a virus and it will be with us for a long time," said Louis Aliot, the far-right mayor of the southern city of Perpignan. "Let's get used to it and start by trying things out."

As the pain of shutdowns has bitten hard, governments have turned to other measures to try to facilitate reopening -- mass testing campaigns and quarantines for travellers are still prominent tools.

Britain is the latest country to order international travellers to undergo several tests while under quarantine.

But the surest sign that the world is far from back to normal comes from Tokyo, where organisers of this summer's Olympic Games have issued a 33-page booklet of rules on social distancing.

Athletes' time in Japan will be minimised to reduce the risk of infection and those staying at the Olympic Village will be expected to "avoid unnecessary forms of physical contact".

Despite this, organisers told AFP on Tuesday that they still plan to hand out roughly 150,000 free condoms to athletes.

"If you have been to the Games before, we know this experience will be different in a number of ways," the guidebook warns, adding that breaching the rules could result in expulsion.