One of the mysteries that still surround Covid-19 is how long and how strong the immunity the infected will acquire over time. In new analyses, researchers found that people who already had coronaviruses and were vaccinated with messenger RNA (mRNA) immunizers developed a ‘hybrid immunity’ and possibly more resistant to the SARS-CoV-2 variants.
In an article published in June in the scientific journal Science, Shane Crotty, an American immunologist at the La Jolla Institute in California, analyzed the immune response in people who have already contracted the disease. The results show that people who have had Covid-19 and were later vaccinated can show antibody responses 25 to 100 times greater.
Another study, which also supports this result, points out that neutralizing cells remain relatively unchanged between six and 12 months after infection and that vaccination further increases immunity.
This set of studies that bring together data on the immune response of infected patients encourages Paul Bieniasz, a virologist at Rockefeller University who helped lead several of the Covid-19 studies. According to him, with the results it can be expected that in the near future, people will be well protected against most and almost all variants of SARS-CoV-2.
In another research (not yet peer-reviewed), conducted with 14 patients who became infected with the virus in 2020 and were vaccinated with an mRNA immunizer, the results showed resistance to six different strains of the virus, including the Delta and Beta variants.
What is the mRNA vaccine
The body naturally uses RNA, a type of nucleic acid very similar to DNA, to make proteins. It works as an intermediary capable of exposing the information present in our genetic code. In other words, RNA helps in the transcription process of the genetic characteristics of individuals that are always contained in the DNA.
In the case of Covid-19, the Pfizer and Moderna vaccines use the mRNA to mimic the spike protein that is present in the coronavirus and that helps the virus invade human cells. Despite this, this copy introduced into our arm is not fatal like the original virus, but it is enough to create reactions in our body and activate the body’s defense cells.
After injection with the spike protein messenger, the body quickly destroys this vaccine mRNA, but creates absorbs the code it carries. The immune cells responsible for this process are called antigens. They spread information from the cell infected by the spike protein copy to other cells called T cells.
T cells have immune functions of antiviral responses, or they produce cytokines or kill the infected cell. The moment it detects part of the spike protein, they emit an ‘alarm’ to other defense cells in the body so they can fight the infection.
After the first encounter with these viral agents, our body creates a ‘memory’ of their RNA. At this point, memory cells begin to be generated, which are long-lived and store information on how to destroy the antigen. If one day we cross paths with the virus again (as we do with the flu almost always), the defense response will be much faster and more effective due to the activation of the cells.
These memory cells can be weaker or stronger, depending on the case. Therefore, the body uses the so-called B lymphocyte, which is activated after recognizing the antigen and converts into a cell called plasma, which actually produces the antibodies.
Most of the time, these cells die as soon as they fight infection in our body, and are called short-lived plasma cells. However, in some cases they can last a lifetime.
At these times, they are stored in the bone marrow, called long-lived plasma cells. That’s why we have immunity against some types of virus that we had contact in childhood, such as measles, mumps and others.
Combination that is good
The combination of natural immunity and vaccine-induced immunity excites scientists, since after contact with the virus, the body produces defense cells and memory cells, which can help to inhibit coronavirus contagion even before the agent. reach the organism.
Despite the encouraging news, Hatziioannou told NPR he didn’t know if everyone who had Covid-19 and took the vaccine soon after will have the same ‘superimmunity’. According to the specialist, this analysis is extremely difficult to do and, for this reason, they evaluated few patients.
And who gets Covid-19 only after vaccination?
For this and other questions, researchers still do not have answers, as the evaluation time is very short.
What is known so far is that vaccines play a key role in lowering the risk of severe cases of the coronavirus, and that they help produce much more flexible antibodies capable of recognizing variants of the virus.
Something that, according to Bieniasz, could make the coronavirus part of a category of viruses that will only bring us a common flu or even a cold.