Study Identifies Role of Neutralizing Antibody in COVID-19 Re-infection, Transmission

A preclinical study of the role of neutralizing antibodies in reinfection and transmission of SARS-CoV-2 offers a further sign of hope, along with increased vaccination rates, for the control of COVID-19. But the current pandemic is unlikely to be our last, and it should be raising awareness of the need to prepare for the next pathogen battle, says Cleveland Clinic virologist Jae Jung, PhD.

Jung is Director of the Center for Global and Emerging Pathogen Research and Human Health and chair of Lerner Research Institute’s Department of Cancer Biology. He was among researchers whose study of SARS-CoV-2 reinfection and transmission was published in January 2021 in the journal Emerging Microbes & Infections.

Jung participated with scientists in Korea to advance understanding of how antibody levels affect the potential for COVID-19 reinfection and transmission. While there have been reports of recovered people becoming re-infected, scientists have suspected that previous infection might offer some degree of protection against new disease. How much remains a question.

The results of the Korean study, Jung says, indicate reasons for optimism as the proliferation of vaccines increase the numbers of people developing neutralizing antibodies (NAb). Still unanswered, Jung says, is “how long will the vaccine protect recipients? Several months? A year? Or is it similar to the polio virus vaccine or measles, lifelong protection? We may have to be continuously vaccinated. That’s definitely the number one issue.”

Key insights on neutralizing antibodies

The study by Young-Il Kim, et al, sought to determine whether higher NAb levels affected the propensity for re-infection and for transmitting the virus to naïve subjects, Jung says.

Model groups were infected with three varying doses of the NMC-2019-nCoV02 virus. Four weeks from the initial infection, they were separated into groups based upon their levels of NAb titers measured in Vero cells (less than 20; 20-40; 80; and 160). Then they were infected with a heterologous strain of the virus. A seronegative naïve group was also infected.

“We found that that those with low or medium levels of neutralizing antibodies were readily re-infected, and they could transmit the virus to a naive model,” Jung says. “On the other hand, those that carried a high level of neutralizing antibody were re-infected initially, but immediately cleared the virus, and they did not transmit to the naive model.”

Jung adds that the model groups were infected with much higher amounts of virus than humans typically experience. Clinical studies will be needed to determine how NAb titers affect human reinfection and transmission. Jung says he is optimistic that vaccines will be proven to help protect against transmission as well as the development of the illness caused by SARS-CoV-2.

The pressing challenge of viral disease

Preparedness is a key lesson to be taken from the COVID-19 pandemic, Jung says. “The most important part of infectious disease is prevention, prevention, prevention,” Jung says, but he adds that it’s also one of the most difficult lessons for people to accept.

“They don’t like to pay money for prevention, because they think ‘There is no disease. Then why do we need to invest the money?’” Jung says.

Investment by the National Institutes of Health over decades helped scientists identify the mRNA technology that last year allowed pharmaceutical companies to quickly develop the first COVID-19 vaccines. Groundwork likewise will better position governments and researchers to face coming pathogens that are arising with increasing speed, Jung says.

The 1918 Spanish flu pandemic, which killed 50 million people, was followed in 1957 by a flu epidemic that began in Asia and spread to the United States. Then came HIV/AIDS in the 1980s; SARS in 2003, H1N1 influenza in 2009, MERS in 2013; Ebola in 2014, Zika in 2016, and COVID-19 in 2019. “The interval is getting shorter and shorter,” Jung says.

His concerns for future threats include mosquito-borne virus and other zoonotic pathogens, as well the possibility that long-dormant virus frozen in ice could be released by the thawing of permafrost as Earth heats up. Most countries have spent heavily to fight COVID-19, and Jung notes that this will complicate efforts to sustain research for the future.