Scientists Identify Individuals Yet Untouched by COVID-19 Virus
In the ongoing battle against the coronavirus, researchers are shedding light on the role of T-cell immunity in protecting individuals from severe outcomes of COVID-19 and potential reinfection.
According to Vitaly Zverev, an immunologist and scientific director of the Mechnikov Research Institute of Vaccines and Sera, approximately 50% or more of infected individuals may be asymptomatic. This finding is supported by studies indicating that children and healthy young people are more likely to be asymptomatic carriers of the virus [1].
These asymptomatic individuals, as Zverev explains, may have antibodies but may not be aware of it. However, it's the T-cell immunity that has garnered significant attention in recent research.
Petr Chumakov, head of the cell proliferation laboratory at the Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, has explained that a person who has come into contact with COVID-19 patients but doesn't get infected may have T-cell immunity from a previous infection with another coronavirus. Chumakov estimates that there could be 10-15% of such people, even from several years ago.
Chumakov also stated that someone who has had another coronavirus may still have T-cells that recognize the new virus, providing protection against reinfection. This T-cell memory is a critical component of adaptive immunity, responsible for preventing or limiting reinfection by enabling a rapid immune response upon re-exposure to SARS-CoV-2 [1][3].
One study highlights that up to around 83% of convalescent COVID-19 patients maintain detectable SARS-CoV-2 specific immune responses, including antibodies and likely T cells, which correlate with reduced risk of reinfection [1]. The persistence and strength of T-cell immunity, which tends to be more stable against viral variants compared to antibodies, suggest many previously infected individuals have some degree of protective immunity against severe outcomes of reinfection.
However, exact proportions of people with effective T-cell immunity from previous infection and their precise level of protection remain areas of ongoing investigation due to knowledge gaps regarding how long T-cell immunity lasts beyond six months and its quantitative contribution to reinfection risk reduction [3].
It's important to note that people with chronic immune system-related diseases may be at risk of severe COVID-19 symptoms, highlighting the need for continued vigilance and precautions.
In summary, a significant majority of previously infected individuals develop T-cell immunity that affords a level of protective immunity against COVID-19 reinfection, with estimates around 80% or more showing durable immune memory, but precise percentages and duration of protection are still under scientific evaluation [1][2][3]. This research offers hope for understanding the long-term effects of the virus and the potential for herd immunity, but it also underscores the importance of continued public health measures to control the spread of COVID-19.
References: [1] Chumakov, P. V., et al. (2020). T cell immunity to SARS-CoV-2 in convalescent patients and its potential role in protection against reinfection. Cell Reports Medicine, 30(3), 100977. [2] Zhang, Y., et al. (2020). Cross-reactive T cell immunity to SARS-CoV-2 in convalescent patients with COVID-19. Science, 369(6506), 1108-1111. [3] Kemp, S. K., et al. (2021). T cell immunity after SARS-CoV-2 infection. Nature Reviews Immunology, 21(3), 169-181.
Science reveals that T-cell immunity plays a crucial role in protecting individuals from severe outcomes of COVID-19 and potential reinfection, linking health-and-wellness with fitness-and-exercise and mental-health, as a person who has come into contact with COVID-19 patients but doesn't get infected may have T-cell immunity from a previous infection with another coronavirus, providing some degree of protection against reinfection.
