Qhow much you are protected from Covid after the vaccine? A crucial question, especially now that the experts are once again underlining the importance of the fourth dose to protect yourself from infection. But, at the same time, a question to which, until today, it was not possible to give a certain answer. However, the scenario seems to be destined to change thanks to one study conducted by Italian researchers of‘IRCCS of CandioloWith the’Italian Institute for Genomic Medicine (IIGM), in the laboratory Armenise-Harvard of Immunoregulation. In fact, scholars have developed a simple blood test capable of overcoming the limits of current serological tests which alone are unable to determine the level and duration of immunity. induced by the new RNA vaccines against SARS-CoV-2 virus.
New test: how it works
The exam, described on the pages of the Nature Immunology journal, consists inidentification of T-cell markers of memory, fundamental in addition to antibodies, to eliminate the pathogen and avoid disease.
«This type of test allows us to measure the response to T-cell virus. – explains Dr. Luigia Pace, head of this research at the IRCCS of Candiolo Laboratory of Oncological Immunology and head of the Immunoregulation Laboratory at the IIGM, among the authors of the study – There immune response against pathogens and infections, also induced by vaccines, is based on two main axes. One is that of antibodiesor of B lymphocytes The other is that of T lymphocytes which specifically recognize the pathogen and generate the immunological memory, remaining in our blood and in our lymphatic organs for a long time ».
The role of T lymphocytes in protection from Covid
Not everyone benefits at the same way of the anti-Covid vaccination. In some people, the immune response against the SARS-CoV-2 virus is stronger and more lasting than in others. It can happen that an individual needs a new dose of Covid vaccine after a few months and another after several months.
“What that our study revealed is that the response to the vaccine yes depends on our antibodies but also from T lymphocytes – explains Dr. Pace – Their presence allows in fact to evaluate the quality of the vaccine-induced response and therefore the possible level of protection against variants. THE In fact, T lymphocytes recognize portions of the Spike protein that I am less susceptible to changes in the virus and this also allows us to recognize the new variants ».
How T lymphocytes work
“T lymphocytes can generate cells of the immunological memory. – continues the head of the study – P.we can imagine them as gods guardians that circulate in our blood and that, as soon as they meet a cell infected by the virus, they are able to recognize it through a receptor, which is called TCR, and to kill it. It is no coincidence that they are also called cytotoxic killers“.
This therefore explains why evaluate and measure the presence of T lymphocytes reactive is crucial for understand if a person is still protected from the infectioneven if it has low levels of antibodies.
The study on the immune reaction to the Covid vaccine
To achieve this result the scholars have examined over 400 subjectssubjected to Pfizer mRNA vaccine.
“We have analyzed the immune reaction against the virusi.e. the responses of the B cells that produce the antibodies, and the response of the memory T lymphocytes against the Spike protein of SARS-CoV-2 or derived from the Beta, Delta and Omicron variants, up to 10 months after vaccination. – says Dr. Pace – We had the opportunity to correlate the value of the antibodies with the presence of T lymphocytes and with the outcome of the infection: some of the subjects involved in our study, in fact, were then infected with Omicron. It was a research on a predictive model but which he later confirmed as the people who had low immune responses yes they are then infected. Basically, through these parameters, we have identified two distinct groupsrespectively with high and low responses to the vaccine. Subjects with superior responsiveness show an increase in central memory T cell frequency even after the booster dose.
The difference with previous Covid tests
The turning point is therefore represented precisely by ability of this new test to quantify T lymphocytes memory, allowing you to measure and then verify whether the immune system is still “armed” against the virus or if it needs to be boosted with a new dose of the vaccine.
THE serological tests available to date instead they aimed to measure the antibodies that alone are not sufficient to predict the level of protection of the subject. “The antibodies they are molecules that recognize the virus but that in order to be effective they must have a neutralizing activity, that is, they must be able to block it. – explains the doctor – For this reason the serology test available todaywhich indicates only the presence of antibodies, it cannot be understood as a tool for assessing the level of protection of the subject and to determine if it is appropriate to undergo another dose of the vaccine ‘.
When will the new test be available?
The results achieved by this study could therefore help define new vaccination strategies and provide valuable information also for the development of new vaccines. But when it will be available in Italy this test?
“Now the test it must be standardizedthat is, criteria must be established that allow all research laboratories to be standardized and after standardization must be approved by the Ministry. – explains Dr. Pace – The premises, however, are good because the test is not based on a difficult technique and it requires inexpensive instruments which are already used, for example, for the leukocyte formula ».
With this test, could we know whether or not to do another dose of Covid vaccine?
«Let’s say that thanks to this test it will be possible identify subjects with very low responses. – concludes the expert – An important factor also for those people who have doubts, because they will be able to evaluate clearly how they are responding to the vaccine“.
In the gellery above, with the scientific advice of Dr. Luigia Pace, the true and the false to know about vaccines, tests and virus protection.
iO Donna © REPRODUCTION RESERVED