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VERIFIED CONTENTConsultation: Piotr Rzymski - Polish medical and environmental biologist, dr hab. medical sciences, popularizer of science

Although only the third dose of the SARS-CoV-2 vaccine is received by other groups of people, the US Centers for Disease Control and Prevention (CDC) is discussing further vaccinations. What group will need them? We asked the medical biologist Dr. Peter of Rome.

Why is the booster dose important?

Dr. Piotr Rzymski points out that “administering a booster dose significantly increases the levels of neutralizing antibodies that block the Delta variant from becoming infected. Research in Israel shows thatpeople who receive it have a 10 times lower risk of infection compared to those who received the first two

Below we present a graph of the dynamics of the serum level of neutralizing antibodies, which shows how the amount of antibodies changed in our interlocutor after vaccination. It shows thatneutralizing antibodies were present 8 months after receiving the second dose of the vaccine, but their levels decreased significantly. However, the administration of the third dose induced him to a concentration exceeding the maximum detection limit .

The expert points out that " while the effectiveness of vaccination against COVID-19 in terms of protection against infection decreases, the level of protection against severe course, hospitalization and death remains - also in the case of the Delta variant - on a very high, even sensational level of 85-90 percent.”. - Very large studies conducted in the USA and published in The Lancet indicate that the effectiveness of the BioNTech / Pfizer vaccine in terms of protection against hospitalization was maintained within 6 months after receiving the second dose at a comparable level, an average of 93%. - he adds.

Who will need the next immunization?

The U.S. Centers for Disease Control and Prevention (CDC) indicates thatpeople with moderate or severe immunodeficiencydue to medical condition, immunosuppressive therapy, or medication may need a fourth dose mRNA vaccinationagainst COVID-19.

According to CDC experts, these are people who:

  • use active treatment of solid tumors and hematological neoplasms,
  • have had a solid organ transplant and have started immunosuppressive therapy,
  • received CAR-T or HCT cell therapy within 2 years of transplantation or immunosuppressive treatment,
  • suffer from moderate or severe primary immunodeficiency (including DiGeorge syndrome, Wiskott-Aldrich syndrome),
  • have HIV (advanced HIV or untreated infection),
  • receive high doses of corticosteroids or other drugs that reduce immunity.

Research on the effectiveness of vaccinations in immunocompromised people

Dr. Piotr Rzymski points out that "by analyzing the available data, it can be concluded thatonly in 50-60 percent. organ transplant patients develop antibodies to the coronavirus S protein after both doses of the vaccine”. - Our studies in four large clinical centers - in Poznań, Wrocław, Kielce and Białystok - confirm that in the group of fully vaccinated people who have become infected and have developed a severe form of COVID-19, there are patients after transplantation and it happens that the result of the test determining the concentration of IgG antibodies against the coronavirus spike protein is negative at the time of hospitalization - explains the biologist.

Experts from Johns Hopkins University conducted a study that showed that 44 percent of people with immunosuppression despite vaccination breakthrough cases requiring hospitalization and are more likely to transmit the virus to people in close contact with them.

Studies have shown that these people were hospitalized 485 times more often or died of coronavirus infection compared to most vaccinated people. The studies confirmed that the booster dose strengthened the immunity of the antibodies to vaccination in some immunocompromised people.

As expert Dr. Rzymski emphasizes, "other studies indicate thatpatients with immunodeficiency are characterized not only by a lower level of antibodies or the lack of them, but may also develop less, if at all, mechanisms of cellular response". - As a result, despite undergoing the primary vaccination regimen, they remain vulnerable to infection and its serious consequences, because they are at increased risk of severe COVID-19, he adds.

Will giving a booster dose improve the situation?

Dr. Piotr Rzymski emphasizes that "researchclinical evidence shows that the administration of a booster dose increases the antibody level in patients who are low after the first two doses, and also reduces the percentage of patients who did not produce antibodies at all ”. - For example, a study conducted in France in kidney, liver, lung, heart and pancreas transplant recipients showed that a booster dose seroconverted half of the patients who did not exceed the positive threshold after two doses.In other words, it was only the third dose that "worked" and overwhelmed the immunosuppression deadlock- explains the expert.

Difference between booster dose and booster dose of COVID-19 vaccine

More and more countries, in line with CDC recommendations, decide to administer booster doses minimum 6 months after receiving the booster dose. Why?

Dr. Piotr Rzymski points out two reasons, but each according to the expert "is intended to increase protection against SARS-CoV-2 infection and is due to two reasons: the observation that serum antibody levels decline within a few months after the completion of the initial vaccination schedule, thereby reducing protection against infection, and the emergence of a more infectious Delta variant which increases the risk of infection among fully vaccinated people. "

The expert explains that the term supplemental dose is defined as "another, additional dose of the vaccine for patients with primary or secondary immunodeficiencies. In the case of mRNA vaccines, this is the third dose for these people. ' -These people, due to the limited efficiency of the immune response, react less well to various vaccinations, and vaccination against COVID-19 is unfortunately no exception to this . Immunosuppression in these people suppresses the possibility of generating a specific immune response. The fourth dose for immunocompromised people, on the other hand, is the equivalent of a booster dose of the third dose for people without immunosuppression, ”adds Dr. Rzymski.

When should immunocompromised people take the next vaccination doses?

According to CDC specialists, the timing of vaccination against COVID-19 should take into account current or planned immunosuppressive therapies, and the dose should be supplemented at least two weeks before starting or resuming immunosuppressive therapies.

Expert Piotr Rzymski explains that "it is advisable that people suffering from immunosuppression perform a serum level of IgG neutralizing antibodies after receiving a supplementary dose (the third dose)against the receptor binding domain (RBD) of the S protein, i.e. IgG anti-S1-RBD antibodies ".

Dr. Rzymski explains that " the result of this study will answer the question of whether the immunosuppressed person responded to vaccination ". - It is very important for the patient, who often lives in fear, realizing the consequences of SARS-CoV-2 infection. It is worth recalling that the death rate due to COVID-19 in patients after organ transplants is significantly increased and, according to the data, may be as high as 20%. - he adds.

The CDC has yet to make a recommendation for a fourth immunization for immunocompromised people, but American scientists point out that these people should talk to their doctors to determine if it will be necessary. We asked the expert whether the referral for another vaccination will be the result of an individual opinion of the attending physician?

-It is always advisable for an immunosuppressed patient under the supervision of a doctor to consult him on vaccination and this should be the case before the fourth dose, which for these people will be the equivalent of the third dose for the rest parts of the population . For the majority of patients with immunodeficiency, the administration of a booster dose (i.e. the fourth dose) should lead to a strong stimulation of antibody production and enhancement of the cellular response - explains Dr. Rzymski.

- It is impossible to say at the moment how long it takes to receive the fourth dose. Please remember that the priority of vaccination against COVID-19 is primarily to mitigate the clinical effects of infection, and secondly to prevent infection.If using the strategy of a booster dose and then a booster dose for people with immunodeficiencies successfully protects them from the more severe course of SARS-CoV-2 infection, there will be no justification for the cyclic administration of the vaccine- the expert concludes.

Piotr Rzymski - Polish medical and environmental biologist, dr hab. medical sciences, popularizer of scienceMedical and environmental biologist, co-author of over 150 scientific publications, academic lecturer, science promoter, science journalist. Scholarship holder of the Foundation for Polish Science and the Ministry of Science and Higher Education, expert of the EU Research Executive Agency, ambassador of the international scientific network Universal Scientific Education and Research Network (USERN), member of the Program Council of the "Science Against Pandemic" initiative

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