There is growing evidence that pre-existing cross-reactive immunity from common human coronaviruses may play a role in the immune response to SARS-CoV-2, the virus that causes COVID-19. Here are some key points:
- T cell responses: Studies have found that people who have never been infected with SARS-CoV-2 can still have T cells that recognize parts of the virus. This is thought to be due to exposure to other coronaviruses, such as those that cause the common cold. These pre-existing T cells may help mount a faster and more effective response to SARS-CoV-2.
- Antibody responses: A study published in Nature in 2021 found that people who had previously been infected with common human coronaviruses had lower levels of antibodies against SARS-CoV-2 compared to people who had not been infected with the common coronaviruses. This suggests that pre-existing antibodies may interfere with the immune response to SARS-CoV-2.
- Severity of illness: Several studies have found that people who have been previously infected with common human coronaviruses may have a milder course of illness when infected with SARS-CoV-2. This is thought to be due to pre-existing cross-reactive immunity that helps the immune system recognize and fight the virus.
Overall, the evidence suggests that pre-existing cross-reactive immunity from common human coronaviruses may influence the immune response to SARS-CoV-2, both in terms of T cell responses and antibody responses, as well as the severity of illness. However, more research is needed to fully understand the nature and extent of this cross-reactive immunity and its implications for COVID-19 immunity and vaccine development.
T cell responses
T cells are a type of white blood cell that plays a critical role in the immune response to viral infections such as SARS-CoV-2, the virus that causes COVID-19. T cells can recognize and target virus-infected cells, helping to clear the infection from the body.
Studies have found that people who have never been infected with SARS-CoV-2 can still have T cells that recognize parts of the virus. This is thought to be due to exposure to other coronaviruses, such as those that cause the common cold. These pre-existing T cells may help mount a faster and more effective response to SARS-CoV-2.
In addition, studies have found that COVID-19 patients with severe disease have lower levels of virus-specific T cells, suggesting that a robust T cell response may be important for controlling the infection and preventing severe disease.
T-cell responses are being studied extensively about SARS-CoV-2 immunity and vaccine development, and are considered to be an important component of the immune response to the virus.
Antibody responses
Antibodies are proteins produced by the immune system in response to an infection, and they play a key role in fighting off the virus that caused the infection. Antibodies can recognize and bind to specific parts of the virus, called antigens, and help to neutralize the virus and clear it from the body.
In the case of SARS-CoV-2, the virus that causes COVID-19, antibodies are produced in response to the spike protein on the surface of the virus. Studies have shown that people who have been infected with SARS-CoV-2 develop antibodies against the virus, and these antibodies can provide some level of protection against future infections.
However, there is also evidence that pre-existing antibodies against other coronaviruses, such as those that cause the common cold, may interfere with the immune response to SARS-CoV-2. For example, a study published in Nature in 2021 found that people who had previously been infected with common human coronaviruses had lower levels of antibodies against SARS-CoV-2 compared to people who had not been infected with the common coronaviruses. This suggests that pre-existing antibodies may interfere with the immune response to SARS-CoV-2.
Antibody responses are being studied extensively about SARS-CoV-2 immunity and vaccine development, and are considered to be an important component of the immune response to the virus. However, the role of pre-existing antibodies and their potential impact on the immune response to SARS-CoV-2 is an area of ongoing research.
Severity of illness
Several studies have suggested that pre-existing cross-reactive immunity from common human coronaviruses may be associated with a milder course of illness when infected with SARS-CoV-2, the virus that causes COVID-19.
One study published in the journal Science in 2020 found that people with no prior history of COVID-19 who had T cells that recognized SARS-CoV-2 had milder symptoms when infected with the virus compared to those who did not have these T cells. These pre-existing T cells are thought to be a result of exposure to other coronaviruses, such as those that cause the common cold.
Another study published in the Journal of Infectious Diseases in 2021 found that people who had pre-existing immunity to common human coronaviruses were less likely to be hospitalized or require ICU care when infected with SARS-CoV-2 compared to those who did not have this pre-existing immunity.
However, it is important to note that the severity of illness in COVID-19 can be influenced by many factors, including age, underlying health conditions, and viral load. While pre-existing cross-reactive immunity may be a factor in the severity of illness, it is likely only one of many factors that contribute to the course of the disease.
Overall, the role of pre-existing cross-reactive immunity in the severity of illness in COVID-19 is an area of ongoing research, and more studies are needed to fully understand its impact.