a A great deal of conflicting information has emerged about the immune response developing in patients who have recovered from Covid-19. newly a study In the UK, antibodies have shown a decline in antibodies in more than 350,000 people, leading to headlines that immunity is rapidly waning just months after infection.
The next day, another a study He concluded the opposite: in more than 30,000 patients in New York City, the majority showed high levels of IgG antibodies, a type of antibody that usually neutralizes the SARS-Covid-2 virus, which causes Covid-19 disease. Of course, this is very confusing. Is Sars-Cov-2 a super powerful virus that can effectively sabotage our immune systems that protect us against many other pathogens? Can people who have recovered from Covid-19 expect to have preventive long-term immunity or not?
The good news is that we are not likely to be infected with Sars-Cov-2 repeatedly until it kills us all in the end. Most of the evidence in both Covid-19 patients and animal models shows that an immune response to this is quite typical of an acute viral infection. Initially, the body increases high levels of IgG antibodies, but after the infection is cleared, these antibodies decrease to the baseline level, which may be below the detection limit for some serological tests.
Antibodies are produced by B cells, which are a specialized type of immune cell that recognizes a specific antigen, or viral target. When the infection is cleared, the antibody-producing B cells, which specialize in pumping massive amounts of Sars-Cov-2 antibodies, are transformed into memory B cells. These cells produce lower levels of IgG antibodies; But most importantly, it lasts in the body for years. If they are exposed again to Sars-Cov-2, they quickly turn into plasma cells and start producing high levels of antibodies again.
There is no indication that most Covid-19 patients do not develop an immune memory, and that animals experimentally infected with Sars-Cov-2 are protected from re-resistance with high doses of the virus. Most people who recover from Covid-19 have neutral antibodies that can be detected months after infection. This indicates that SARS-Cove-2 infection is already producing a protective immune response, for at least several months. To determine how long this protection will last, unfortunately, we have no choice but to wait. The SARS-Cov-2 virus has been circulating in humans for less than a year, and there is no way to study immune robustness other than wait-and-see.
Moreover, antibodies are not the only important part of the immune system. T cells are also a major component of the immune response. It comes in two flavors: helper T cells, which coordinate immune responses and facilitate immune memory, and killer T cells that kill infected cells. Previous studies have shown that SARS-Cove-2 infection induces robust T cell responses.
Interestingly, some people who have never had Covid-19 before have had memory T cells from a previous cold coronavirus infection that interacts with Sars-Cov-2, indicating that there may be some Protection existing among the population . It is important to note that the role of T cells in protecting against SARS-CoV-2 is largely unknown and this is an active area of research. T cells alone are unlikely to provide complete immune protection, but they are a major contributor to immune memory, and it shows that antibody levels alone do not tell the full story of protective immunity.
The responses of these cells also confirm that SARS-Cove-2 is not an abnormal virus capable of achieving breakthrough feats of immune evasion. Sars-Cov-2 can definitely suppress some antiviral responses, which is likely the reason why it causes severe Covid-19 in some people, but it is not immune to our immune defenses.
While some cases of infection have been reported again, there is currently no evidence that this is common. It is also possible that reinfection in people with partial immunity could lead to milder disease, although this remains an untested hypothesis. More research is needed into re-infection to understand how common it is, but we should not take it as evidence that immunity is not working nor hope for preventing Sars-Cov-2 in the future.
On the contrary, there is Promising results In animal studies and clinical trials, candidate vaccines produce levels of antibodies equivalent to the cure for patients with the highest levels of antibodies that these antibodies tolerate. It is true Pfizer vaccine recently announced that it prevents symptomatic cases of Covid-19 after an interim analysis of Phase 3 experimental data. This indicates that vaccines may provide stronger and lasting protection against natural infection.
Our search for functional immunity to SARS-Cove-2 is no more a biological problem than a psychological one. To explain the widespread prevalence and death, the chronic debilitating disease that has led to many Covid-19 patients clearing the infection but never recovering from the disease, and the severe disruption of our daily life, it is tempting to think that the virus is a unique pathogen that we have not seen before.
Indeed, it is our inadequate policies and our lack of an evidence-based public health strategy that have got us where we are today in the US, the UK and most of the rest of Europe. Our immune systems mostly respond to this virus in the way we expect; It is our leadership whose responses have failed.
• Angela Rasmussen is a virologist with the Georgetown Center for Global Health and Security Sciences