Representative Image
(Xinhua / Evgeny Sinitsyn / IANS)
As the majority of the world collectively holds its breath while waiting for the COVID-19 vaccinations, indirect protective measures, such as social distance and wearing masks, have kept people out of reach of the coronavirus. In addition, the development of antibodies in individuals who successfully conquered the virus also served as an ‘anti-virus’ protection for themselves and the people around them.
But with that said, there has been constant speculation about how long these antibodies and general immunity against COVID-19 last in the human system. The clouds of mystery pertaining to this particular issue continue to govern scientists, virologists and researchers. So far, several studies have suggested that antibodies against the infection may decrease in just a few months after recovery, thus raising concerns about contracting the infection more than once.
Now, a team of scientists from Monash University, Australia, has given the world a Christmas gift through its new study, which indicated that immunity against COVID-19 can last at least eight months. The research is even more significant at the moment, when vaccines are still being implemented.
“This has been a black cloud hovering over the potential protection that could be provided by any COVID-19 vaccine and gives real hope that once a vaccine or vaccines are developed, they will provide long-term protection,” said immunologist Menno van Zelm of Monash University.
Examining B memory cells
The new study specifically took into account a type of cells in our immune system known as memory B cells or MBC. These cells work to remember any infection that the human body contracts after being invaded by a pathogen, for example, a virus. Therefore, if an individual contracts the virus again, the MBC works to trigger a protective immune response through its memory and thus protects the individual from reinfection.
To understand the presence of memory cells, the team pursued two main components of the SARS-CoV-2 virus – the peak and the nucleocapsid proteins. The study noted that memory B cells were rapidly generated in all patients after infection and remained detectable after 240 days. This very prolonged presence of memory cells shows a long-term immune response to COVID-19. It also highlights the fact that the patient’s immune system has the ability to fight when re-exposed to the pathogen for the rapid production of antibodies.
“These results are important because they definitely show that patients infected with the COVID-19 virus do in fact retain immunity against the virus and the disease,” said Dr. van Zelm.
Representative Image
(Xinhua / Wang Jingqiang / IANS)
Interestingly, the study also found that even after months of spreading the virus, during which millions of positive infections were found, there were not many reported cases of reinfections among the population worldwide.
A similar study was recently published in the journal Emerging infectious diseases, which also confirmed the presence of antibodies against SARS-CoV-2 after 8 months of infection in most asymptomatic or mildly symptomatic patients. The study was carried out by means of the immunoassay test in 58 positive patients.
Antibodies start to disappear in 20 days
When attacked by a pathogen, our immune system produces proteins called antibodies to fight infection. If the infected person can produce enough antibodies, he can recover from the disease caused by this pathogen.
To examine how long these antibodies last in the case of COVID-19, the researchers monitored about 25 people diagnosed with different severities of the disease and then collected post-infection blood samples from them – starting from day 4 to day 242 after the recovery. On the other hand, they also obtained data from 36 healthy patients in the control group between March and September, to compare the presence of antibodies in each patient and the levels of virus-specific immune cells.
After examining this long-term data, the researchers noted that antibodies against COVID-19 – especially immunoglobulin (IgG), which is the most common antibody in the human body – started to disappear in just 20 days after infection, as well as the previous studies suggested.
Previously, similar research conducted by Chongqing Medical University in China also suggested that people who recovered from COVID-19 had a sharp decline of up to 90% in their immunoglobulin (IgG) antibodies over a period of 2-3 months .
The new research is a collaborative effort between Monash University, The Alfred Hospital and the Burnet Institute in Melbourne. The study was published in the journal Scientific Immunology on December 22nd, and can be accessed here.
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