A Covid-19 survey led by China’s top respiratory disease expert Zhong Nanshan found that the population immunity was at a low level, underlining the “urgent need” for a vaccine.
The survey tested the presence of antibodies in the serum of over 16,000 people who had not fallen ill from the disease in Wuhan, the initial epicentre of the pandemic, and the southern city of Guangzhou.
It found only 2.14 per cent and 0.59 per cent of people in the respective cities had Sars-CoV-2 antibodies by the end of April.
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“The relatively low [level] suggests that prevention and control measures in China are effective,” the researchers wrote in a letter published in the journal Cell Research on Monday.
“[But] whether inside or outside the epicentre of the outbreak, the population immunity is still at a low level. Therefore, there is an urgent need for an effective vaccine against Sars-CoV-2, and strict isolation and community measures should be continued until such a vaccine is available,” they wrote.
Zhong, who played a key role in the battle against severe acute respiratory syndrome (Sars), told a public forum last month that it would need at least 60 to 70 per cent of a country’s population to have the antibodies before herd immunity could be attained, and it should happen through vaccination rather than naturally.
According to the World Health Organisation, there were 24 candidate vaccines in clinical evaluation as of Monday. This week The Lancet reported that two vaccines – one from CanSino Biologics and the Beijing Institute of Biotechnology, and the other from Oxford University and AstraZeneca – had both produced positive trial results.
Since the disease was first reported late last year, there have been more than 83,000 confirmed cases in China, including over 50,000 in Wuhan and 377 domestic cases from Guangzhou.
Local outbreaks have flared up since the disease passed its peak, including one in Urumqi this month, but the number of patients being treated for Covid-19 in hospital stood at just 242 on Monday.
In the survey, researchers studied 8,782 people including inpatients and hospital visitors at the First Affiliated Hospital of Guangzhou Medical University starting on January 20. Another 8,272 outpatients admitted since March 9 to the Hubei Cancer Hospital, in Wuhan, were also tested.
The median age of Wuhan and Guangzhou participants was 54 and 55 respectively.
All individuals in both groups tested negative for the coronavirus and most of them showed no Covid-19-related symptoms in the previous three months.
The researchers explained that presence of antibodies in serum indicates early or prior infection by the coronavirus, and the serological investigations they carried out could comprehensively identify the infected people in the community, especially those with mild or no symptoms.
There was no significant difference between different ages and genders in the Wuhan study.
The researchers cautioned that the study result may have been skewed because it focused on people with no Covid-19 symptoms and patients being treated for other illnesses.
George Gao Fu, the director general of the Chinese Centre for Disease Control and Prevention, said in May that China was drafting an immunisation plan that would factor in the progress made in researching vaccines.
Chinese media outlet Caixin reported on Monday that Wang Huaqing, the centre’s immunisation planning chief, had told a forum on Friday that even after a vaccine becomes available, the authority would need to decide its top priority when supplies are still limited: whether that is minimising deaths, reducing outbreaks or protecting the vulnerable.
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This article Coronavirus: low level of antibodies present in China’s population and vaccine is needed ‘urgently’, says country’s leading expert Zhong Nanshan first appeared on South China Morning Post