Fewer than four percent of people in Wuhan, the city where the coronavirus pandemic began last year, have antibodies to the virus that causes COVID-19, a new study suggests.
The first epicenter of the coronavirus pandemic, the virus quickly spread to thousands in Wuhan, overwhelming its health care system and forcing weeks of draconian lockdowns.
It seemed the virus was everywhere – especially after solid evidence emerged that many cases of COVID-19 are asymptomatic.
But the new study, published Friday in JAMA Network Open, suggests that the vast majority of people who were never diagnosed with coronavirus never had it.
Or, if they did, the immune proteins that scientists think likely offer protection against reinfection have waned beyond the point of being detectable since the virus first laid waste to the Chinese city last winter.
As a controversial coronavirus response strategy that relies on herd immunity gains traction in the UK and US, the new findings offer yet another worrying sign that the even the populations hit earliest and hardest by coronavirus may still have low rates of protection against additional waves.
Fewer than four percent of people with no history of COVID-19 (far right) in Wuhan, the Chinese city where coronavirus emerged last year, have antibodies against the infection, suggesting the pandemic’s first epicenter is far from herd immunity. Higher rates of antibodies were seen in older people and women (medium blue) in the city of 11.08 million
After its emergence in Wuhan – first observed as a mysterious form of pneumonia – coronavirus rapidly spread to more than 68,000 people in the Hubei province, of which Wuhan is one of the largest cities.
Hospitals were overwhelmed. Authorities went door to door in full PPE, testing members of households, and urging them to stay indoors.
Two hospitals were constructed with astounding speed just to hold all of the city’s coronavirus patients.
In under two weeks, the pair of ‘instant’ facilities added another 2,500 beds to Wuhan’s capacity. There were enough patients to nearly fill them both.
The city of 11.08 million people eventually got its outbreak under control, but not before confirming that about 0.6 percent of its population had been infected.
With an asymptomatic infection rate of about one in five cases, it would stand to reason that much more of the population was infected than was confirmed.
However, China undertook a massive feat in May: every Wuhan resident over age five was tested for coronavirus.
The health officials found 300 more totally asymptomatic infections, but none of the patients’ family members had caught the virus.
Parallel to the government’s coronavirus tests, the researchers at Tongji Hospital of Huazhong University of Science and Technology in China tested more than 35,000 Wuhan residents with no history of a COVID-19 diagnosis for antibodies against the infection between March 27 and May 26.
None of them had IgM antibodies alone, the type of specialized immune proteins that the body develops shortly after infection.
These multiply over the first few weeks of infection, then subside as the body starts churning out IgG antibodies, which are more likely to offer lasting protection.
IgG antibodies are what public health experts hope will keep future waves of the pandemic from infecting and killing as many as 2020’s devastating battle with coronavirus has done.
In less than two weeks, two massive ‘instant’ hospitals were constructed in Wuhan in February to handle the overflow of coronavirus patients in the pandemic’s epicenter (file)
About 0.7 percent of the trial participants had both types of antibodies suggesting their immune system’s long term protection was still developing, and they had been infected some weeks prior.
Just 3.2 percent of the tens of thousands of recruits had longer-lasting IgG antibodies alone, meaning that altogether, just 3.9 percent of the group had any antibodies.
With a sample as large as 35,000, the new study’s findings are statistically considered an accurate representation of the city’s population.
People were more likely to have any antibodies if they lived in the more urban areas of Wuhan, compared to less populous one.
Women were more likely to have antibodies, with aligns well with the higher rate of cases among women in China (although men are more likely to have higher concentrations of antibodies, and to die of the infection).
Similarly, elderly people in the study were also more likely to have antibodies to coronavirus, signalling they had already had the infection – but the study included a relatively low number of people older than 60 or younger than 18, meaning it was less representative of this group.
The findings have several key implications.
For one, the population of Wuhan is one of the most tested in the world. If fewer than four percent of the study participants have had coronavirus as proven by the presence of antibodies, and just 0.6 percent of all residents were previously diagnosed, only a very small proportion of the population has been infected.
Wuhan has seen no instances of ‘community transmission’ since May, and citizens celebrated ‘National day’ in the streets earlier this month (file)
The city is even holding an opera (pictured) and months-long exhibition to commemorate its fight with coronavirus, even as much of the world remains inundated with cases (file)
In a way, this is a good thing. With just 23 total cases diagnosed Sunday in the surrounding Hubei province, according to Johns Hopkins University’s data, it seems the spread of the virus is under control and it is not currently a deadly threat to much of the Chinese region’s population.
But it also suggests that the area of the world that has dealt with coronavirus longest is still nowhere near herd immunity, which scientist think could happen at the earliest when 20 percent of a population has had COVID-19 and has some immunity against reinfection, which will also keep them from passing it onto others.
Other scientists think the necessary herd immunity level is closer to 70 percent of a population.
If so few people have already been infected, allowing the virus to spread freely to accelerate the coming of herd immunity – as the controversial Great Barrington Declaration urges – could quickly hamstring workforces and overwhelm hospitals as the infectious disease spreads through a largely unprotected populations.
The alternative explanation for the low rate of antibodies in the 35,000 trials participants is that more of them have had coronavirus, but those immune proteins have already faded. In that case, protection may have faded as well.
But we still don’t know how much protection antibodies offer, for how long, or what levels of the immune proteins in the blood signal protection or vulnerability.