It is barely more than a year since scientists in southern Africa first detected the coronavirus Omicron variant, which, along with its myriad sub-variants, went on to become dominant around the world.
Omicron spreads more easily than earlier variants, but causes less severe illness and fewer deaths in general, statistics have shown.
However, a surge in cases may lead to increases in admissions to hospital and deaths. Omicron caused Covid-19 infection and death rates to soar in many nations.
But, 12 months on, the latest figures from the World Health Organisation indicate that the disease is causing a little more than 8,000 deaths a week worldwide — the lowest figure since March 2020, when the pandemic was declared by the WHO.
In 2021, there was no single week when fewer than 40,000 Covid-19 deaths were recorded.
While much of the world is seeing more variability after the initial Omicron-induced surge faded in the early months of this year, case numbers and deaths have remained much lower.
Major nations as diverse as Brazil, France, India, Indonesia, Nigeria, South Africa and the US all appear to have put the worst of the pandemic behind them, even if in some instances Covid-19 deaths are still running in the hundreds — or low thousands in the case of the US — per week.
Life has largely returned to its pre-pandemic state, with high vaccination rates, natural immunity from previous infection and Omicron’s reduced pathogenicity causing Covid-19 to merge into the background of other respiratory infections.
This has allowed travel restrictions to be lifted and caused a reduction in requirements for mask-wearing, testing and self-isolation.
People 'dying with Covid, not from Covid'
It is now "a rarity" for Covid-19 to cause someone to be admitted to hospital in the UK, says Ian Jones, a professor of virology at the University of Reading in the country, "and a particular rarity if someone dies of it". The pneumonia that caused so many deaths, especially early in the pandemic, is much less common than it was.
"It’s more a case of them dying with Covid than from Covid," he says. "For sick people, whichever respiratory virus was doing the rounds would be what [killed them] in the end."
Sub-variants of Omicron now account for the overwhelming majority of Covid-19 infections globally. Many non-Omicron variants or sub-variants are detected at extremely low levels or are no longer seen at all.
Tests have shown that Omicron replicates faster than some earlier forms of the virus in the bronchus — the tubes that run from the windpipe to the lungs — which helps explain why it spreads easily.
But it replicates much slower than other variants in the lungs, a key factor in why it typically causes less severe disease.
"It’s attenuated and it’s done it very quickly," Prof Jones says of the coronavirus. "It’s now an upper respiratory infection almost exclusively, which is why it transmits better. It’s just much better at getting around.
"The damage originally was getting pneumonia and ground-glass [x-rays of the lung]. That’s gone because it doesn’t seem to go into the lower parts of the respiratory system."
Nevertheless, this week Anthony Fauci, the departing director of the National Institute of Allergy and Infectious Diseases in the US and the chief medical advisor to the US president, urged people in his country to have a Covid-19 booster vaccination.
The messenger RNA (mRNA) vaccines from Pfizer-BioNTech and Moderna have been updated to take account of Omicron, so offer greater protection now than the original forms of these vaccines.
The effects of long Covid
Countries that previously experienced high infection rates have been left with a debilitating legacy of long Covid, typically defined as symptoms that linger for more than a month.
Aside from huge death rates in the US — where more than a million people died from Covid — data from the US Census Bureau collected in June and analysed by the Brookings Institution think tank in Washington DC indicates that about 16 million working-age Americans have long Covid, of whom between two and four million are not working as a result.
And a study published this month by researchers at Washington University School of Medicine in St Louis, using data from the US Department of Veterans Affairs, found that the risk of long Covid and other serious complications rises after a first infection.
The results indicate, the researchers said, that vaccinated people who have previously had Covid should still take precautions to prevent getting infected again. Other experts have suggested that risks plateau as the number of infections an individual has had increase.
Prof Jones says that for people who have already received multiple vaccine doses, "there probably isn’t much need" to get an additional shot. This may change, however.
"It all depends on whether you get lifetime immunity from using the current vaccine," he says. "The problem for Covid in particular is that coronaviruses seem to evade immunity and in particular with mRNA vaccines, we don’t know how long immunity will last, because they haven’t been round long enough."
Where is Covid getting worse?
In a continuation of the widely divergent national pictures that have characterised the pandemic from the beginning, several countries, such as Australia, China and Japan, that missed out on the worst effects of the coronavirus in the first two years, saw the situation become much more serious in 2022.
Sometimes this was because the ease at which Omicron and its subvariants such as BA.5 spread made it much harder to suppress case numbers and these newer variants often evaded immunity from prior infection or vaccination.
Australia had recorded about 2,250 deaths by the end of 2021, but when late that year the country moved away from a zero-Covid strategy, which involves trying to eliminate rather than live with the coronavirus, case numbers rocketed and the death toll rose to above 15,000.
Japan's case numbers also surged in 2022, in part because of BA.5, and more than 60 per cent of its Covid-19 deaths have happened this year.
China, in attempting to retain a zero-Covid policy, is now something of an outlier nearly three years on from the pathogen’s emergence in Wuhan.
Disruptive efforts to prevent the spread of the virus remain in place and society appears a long way away from living with the virus.
Cracks in the approach spearheaded by President Xi Jinping's government are growing, with the country experiencing a record number of daily cases on Wednesday, at 31,527.
The country’s population remains more vulnerable to Covid because of a lower level of natural immunity, poor vaccination rates — a particular problem among elderly people — and limited efficacy of the domestically developed vaccines.
One concern is that high levels of infection could cause significant spikes in deaths among the elderly on the mainland, just as they did in Hong Kong care homes earlier this year, where vaccination rates among the elderly were also low.
"My concerns remain around China. It’s got a large population that’s susceptible because they don’t use the mRNA vaccines," says Dr Bharat Pankhania, a senior clinical lecturer and senior consultant in communicable disease control at the University of Exeter in the UK.
"In a large population, such as China’s … the immunity produced [by their vaccines] is not as long-lasting. Where the modern mRNA vaccines have been deployed, these countries are in a better position."
China's zero-Covid policy has kept the official death toll from the coronavirus on the mainland to 5,232, a tiny figure for a country of 1.4 billion people.
This number is thought by many analysts to massively underestimate the true figure, but the country’s efforts to suppress infections mean that total deaths — and the numbers suffering from long-Covid — are probably much lower than they would otherwise have been.
But in keeping more of its people alive, China has caused its economy to take a hit and prevented life from returning to normal. A year on from the emergence of Omicron, the pandemic remains front and centre in the world's most populous nation.