By Dennis Thompson
HealthDay reporter
FRIDAY, March 19, 2021 (HealthDay News) – Less than one in ten people in Wuhan carried COVID-19 antibodies in their bloodstream four months after the coronavirus outbreak in the Chinese city, which served as a harbinger of a global pandemic, study shows .
According to the report published March 18 in The Lancet Journal, only about 40% of these people tested positive for the type of neutralizing antibodies needed to fight off future infection.
These data show that a large part of the population in Wuhan was not infected there months after the outbreak and therefore mass vaccination will be required to achieve herd immunity, the Chinese researchers argued.
“Even in the epicenter of the pandemic with more than 50,000 confirmed cases as of April 8, 2020, the estimated seroprevalence is [bloodborne evidence of infection] Wuhan remains low, “suggesting vaccinations will be required to boost herd immunity, study author Dr. Chen Wang said in a press release in a magazine. He is president of the Chinese Academy of Medical Sciences and Peking Union Medical College.
However, a US expert offered to limit the results.
The spread of COVID-19 in Wuhan has been hampered by strict government-imposed lockdown measures, noted Dr. Amesh Adalja, a senior scientist at the Johns Hopkins Center for Health Security in Baltimore.
Because of this, it is difficult to compare Wuhan’s experience with that of US cities with less restrictive lockdowns and higher infection rates, he said.
“In cities with aggressive measures similar to Wuhan, vaccination would remain the solution to protect the population from the recurrence of cases,” Adalja said. “The low prevalence in Wuhan does not apply to other cities that have reported much higher seroprevalence.”
The poll of more than 9,000 residents of Wuhan found that just under 7% of the city’s population had COVID-19 antibodies by April 2020, the researchers reported.
About 40% of patients had neutralizing antibodies to COVID, and the blood test showed that these antibodies remained at stable levels for at least nine months.
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People with confirmed COVID or COVID-like symptoms tended to produce higher levels of neutralizing antibodies than people who were infected but asymptomatic, researchers said.
More than 4 out of 5 reported COVID infections were asymptomatic, “suggesting that in many infected people, symptoms are too mild to require medical attention,” the researchers wrote.
“The exceptional, rapid and effective control measures implemented in Wuhan may have limited the spread of the virus, but also reduced naturally acquired herd immunity by cutting off the development of sustained neutralizing antibodies,” said researchers at the Peter Doherty Institute for Infection and Immunity wrote in a comment accompanying the study.
“Effective global management of COVID-19 is likely to succeed or fail based on the immunity induced by natural infections, especially vaccinations. Given the relative lack of neutralizing antibodies from natural infections, the study reinforces … the need for effective COVID- 19 vaccines to control disease at the population level, “say authors Richard Strugnell and Dr. Nancy Wang.
More information
Learn more about COVID-19 at the U.S. Centers for Disease Control and Prevention.
SOURCES: Dr. Amesh Adalja, senior scientist at the Johns Hopkins Center for Health Security in Baltimore; The Lancet, study and press release, March 18, 2021
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