As the COVID-19 pandemic has progressed over the months, the question of how long the antibodies against the SARS-CoV-2 coronavirus are present in the body has had varying answers. Now a study by Portuguese researchers has found that the majority of patients have detectable antibodies against COVID-19 for up to seven months after the contraction of the infection. Also, while men produce more antibodies during the initial stages of the infection, the levels are more or less than the same by the time the infection runs its course.
According to the cross-sectional study involving a team of interdisciplinary experts from a consortium of five institutions, 90 percent of the study subjects were found to have detectable antibodies from 40 days up to seven months after being afflicted with the disease. They also discovered that age is not a confounding factor in the levels of antibodies produced, however, the severity of the infection is.
"Our immune system recognizes the virus SARS-CoV-2 as harmful and produces antibodies in response to it, which helps to fight the virus. The results of this 6 months cross-sectional study show a classic pattern with a rapid increase of antibody levels within the first three weeks after COVID-19 symptoms and, as expected, a reduction to intermediate levels thereafter," explained Dr. Marc Veldhoen, corresponding author of the study, in a statement.
Unlocking the Mysteries of Antibodies
The study, which was conceptualized in March 2020, monitored the levels of antibodies found in over 300 hospitalized patients and health workers, and over 200 post-COVID-19 volunteers across different age groups. For this, an in-house sensitive versatile and specific COVID-19 serology test was organized. Next, they optimized and validated the assay as a part of Serology4COVID, a consortium of five research institutions in Portugal.
It was found that during the adverse phase of the infection, elevated levels of antibodies were found in subjects in whom the severity of the disease was higher. Additionally, the authors also learnt that age was not a confounding factor in the production of antibodies, as it was observed that there was no notable difference between age groups.
Do Men Produce More Antibodies Against SARS-CoV-2?
Recent studies have shown that age and gender may serve as vital factors in the level of production of antibodies and their potency. For example, a study co-led by Johns Hopkins Bloomberg School of Public Health found that older men who were hospitalized for severe COVID-19 were ideal candidates for being donors of convalescent plasma therapy.
As mentioned earlier, the current study found that age was not a criterion for the levels of antibodies produced by the body. However, it found that amount of antibodies produced in men were elevated during the beginning stages of the infection, but the levels in men and women became nearly the same by the time they recovered.
Dr. Veldhoen, added, "In this early response phase, on average men produce more antibodies than women, but levels equilibrate during the resolution phase and are similar between the sexes in the months after SARS-CoV-2 infection." According to the scientists, 90 percent of subjects worldwide have detectable antibodies up to 7 months after the contraction of the novel coronavirus infection.
Effective Neutralizing Activity Against SARS-CoV-2
After making observations about the duration of the presence of the antibodies, the scientists focused on evaluating the function of these antibodies against the novel coronavirus. They examined the neutralizing ability of the antibodies produced in the volunteers and patients. Interestingly, the authors discovered that while there was a reduction in the level of antibodies with time, the neutralizing assay results showed a powerful counteractive response for up to seven months after infection in a majority of the screened subjects.
With more research geared towards understanding the protection provided by the antibodies, Dr. Veldhoen averred that the current study can facilitate future longitudinal analysis centering on protective immunity to SARS-CoV-2. "The next months will be critical to evaluate the robustness of the immune response to SARS-CoV-2 infection, and to find clues for some open questions, such as the duration of circulating antibodies and the impact of reinfection," he said.