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Currently, periodic COVID-19 testing is mandatory for employees of educational and personal healthcare institutions, pharmacists, and those working in the field of social services. Other staff are required to take the test once before returning to work.
The exceptions apply to people who have been confirmed with COVID-19 less than 180 days ago by PCR or rapid antigen test and who have received a positive serological test less than 60 days before, unless the serological test is performed after of vaccination.
An exemption is also provided for those who were vaccinated with COVID-19 less than 180 days ago according to the full vaccination schedule. It is true that a person may not participate in the tests later on, but then he must check every two months for the presence of antibodies. As confirmed by SAM, the number of serological tests is not limited.
Immunity fades
When asked to explain why mandatory tests are provided for vaccinated people, a communicable disease specialist, prof. Saulius Čaplinskas drew attention to the “period of validity” of immunity.
“The problem is that communication is failing and people are not fully aware of how the vaccine works, that immunity fades over time, both after illness and after vaccination. That is why, over time Unfortunately, most people do not seem to have immunity for more than 1 to 2 years compared to other coronaviruses.
From here, it is logical that half a year after a full vaccination, you should start looking at how much neutralizing antibody is left, how much immunity is left. Because it is formed in a different and individual way for each person ”, he explained.
Immunity is not just about antibodies
Experts point out that the immune response is defined not only by the amount of antibodies, but also by the so-called cellular immunity. However, so far routine tests are done only to determine the antibody titer.
In such cases, would the absence of antibodies already mean that there is no immunity? S. Čaplinskas explained the difference between these “instruments” of immunity.
“The bottom line is that neutralizing antibodies, when in sufficient quantities, simply prevent the virus from entering cells when it enters the human body, in other words, the disease does not develop. Cellular immunity begins to activate and produce antibodies after about 3-4 days. Therefore, if good cellular immunity is maintained, it protects the person not from illness but from serious illness. But the virus will enter the cells, although the disease can be asymptomatic.
Today, research on cellular immunity is quite complex and is mainly carried out for scientific purposes, but I think the time will come when it will also be possible to use them routinely, ”said S. Čaplinskas.
As he added, although a general antibody titer is now being determined, it would be even better to identify a specific group of them: the neutralizing antibodies.
“These assays are already available and are generally commercially available enzyme-linked immunosorbent assays,” said the interviewee.
Time to think about booster shots?
At the same time, S. Čaplinskas pointed out that in order to compare the obtained research results, the test must be carried out in the same laboratory.
“Here is an example, when the Seimas members were examined after being vaccinated, the antibody titer was 250 in one and close to 4,000 in another. Thus, when the test is carried out in different laboratories, the numbers are different ”, explained the interlocutor.
According to him, half a year later it would be logical to observe the amount of antibody that remains.
“And then decide whether to do the test again or to revaccinate after a while. Because now is the time for everyone to start thinking and understanding how to protect themselves next fall, “warned S. Čaplinskas.
Antibodies remain in Nemenčinė patients after one year
According to the immunologist prof. From the VU Life Sciences Center. According to Aurelia Žvirblienė, the time of 6 months after the illness and vaccination, when there is no need for mandatory tests, is more theoretical and is chosen “by insurance”.
“Officially, no manufacturer has said that immunity lasts for only 6 months after vaccination, but both Pfizer and Moderna have announced that protection will last at least 6 months. More data on the duration of immunity is likely to emerge in the future. , and each country may have to set its own rules on when booster vaccination is appropriate Immunity is likely to last more than 6 months after vaccination and relapse.
Here I can give an example from Nemenčinė: After rechecking people who contracted COVID-19 last spring, we see that enough people still have antibodies a year after the disease, although the level of antibodies has decreased. So here also more and more data appear ”, explained the researcher.
Although there is currently no data on the longest period for which immunity is granted, he added that he believes such rules on the need for testing may also change.
For booster vaccines, manufacturers await recommendations.
According to the interlocutor, although there is currently no information on a possible revaccination in the vaccine leaflets, more scientific data should be available in the near future. Vaccine manufacturers and the European Medicines Agency should have a say in this regard.
Among other things, A. Žvirblienė believes that although the manufacturer has not commented on the need to administer a third vaccine to people who have not developed antibodies after two doses of the vaccine, there should be official recommendations on the subject of vaccination of reinforcement.
“It just came to our notice then. It’s only important to understand that two doses of vaccine are not considered when it comes to a booster shot. A single dose should be sufficient. The only question is when it should be injected.
It is possible that the elderly or those with serious cancer diseases can be selectively revaccinated when the immune response is poorly developed or more rapidly suppressed. Therefore, the booster vaccination can be started earlier for those people and later for the younger people, ”he said.
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