Vaccines Needed to Stop COVID’s Spread
FRIDAY, March 19, 2021 (HealthDay News) – Less than one in 10 people in Wuhan carried COVID-19 antibodies in their bloodstream four months after the coronavirus outbreak in the Chinese city that served as a harbinger of a global pandemic, a new study shows.
In addition, only about 40% of those people have tested positive for the type of neutralizing antibodies needed to ward off future infection, according to the report published on March 18 in The Lancet newspaper.
These data show that a large portion of Wuhan’s population remained uninfected for months after the outbreak, so mass vaccination will be needed to achieve herd immunity, Chinese researchers argued.
“Even at the epicenter of the pandemic, with more than 50,000 confirmed cases as of April 8, 2020, the estimated seroprevalence [bloodborne evidence of infection] in Wuhan remains low, “suggesting that vaccinations will be needed to promote herd immunity, study author Dr Chen Wang said in a press release. He is president of the Chinese Academy of Medical Sciences and Peking Union Medical College.
But an American expert warned of the results.
The spread of COVID-19 in Wuhan has been hampered by tough government-imposed lockdowns, noted Dr Amesh Adalja, senior researcher at the Johns Hopkins Center for Health Security in Baltimore.
Because of this, it’s hard to compare Wuhan’s experience to that of U.S. cities with less restrictive lockdowns and higher infection rates, he said.
“In cities that had put in place aggressive measures similar to Wuhan, vaccination would remain the solution to protect the population from an upsurge in cases,” Adalja said. “The low prevalence in Wuhan is not applicable to other cities that have reported much higher seroprevalence.”
The survey of more than 9,000 Wuhan residents found that just under 7% of the city’s population carried COVID-19 antibodies by April 2020, the researchers reported.
About 40% of them had neutralizing antibodies against COVID, and a follow-up blood sample revealed that these antibodies remained at stable levels for at least nine months, according to the study.
People with confirmed COVID or COVID-like symptoms tended to produce higher levels of neutralizing antibodies than people who were infected but asymptomatic, the researchers said.
More than 4 of the 5 reported COVID infections were asymptomatic, “suggesting that symptoms in many infected people may be too mild to require medical attention,” the researchers wrote.
“The extraordinary, rapid and effective control measures implemented in Wuhan could have limited the spread of the virus, but also reduced the herd immunity acquired naturally by truncating the development of sustained neutralizing antibodies,” researchers at the Peter Institute Doherty for the University of Melbourne Infection and Immunity wrote in a commentary accompanying the study.
“Effective global management of COVID-19 is likely to succeed or fail on the basis of immunity induced by natural infection and, in particular, vaccination. Given the relative scarcity of neutralizing antibodies by natural infection, the study … reinforces the need for an effective COVID 19 vaccine in population-level control of the disease, ”commented authors Richard Strugnell and Dr. Nancy Wang.
The US Centers for Disease Control and Prevention has more on COVID-19.
SOURCES: Amesh Adalja, MD, senior researcher, Johns Hopkins Center for Health Security, Baltimore; The Lancet, study and press release, March 18, 2021
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