They can’t help but get vaccinated against Covid-19, but their particularly fragile conditions reduce the effectiveness of the protection. It happens to immunosuppressed patients and not only to elderly ones. Now as many as five studies by the Bambino Gesù Children’s Hospital reveal that this vaccination coverage gap also affects frail subjects between the ages of 12 and 25. The latest study, on children and teens with perinatal HIV infection, has just been published in the journal Clinical Infectious Diseases.
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I 5 studied Convers
Young age is not always synonymous with strength and health. The classification of ‘fragile subject’ can also come from children or adolescents when one is struck by a serious illness and becomes immunosuppressed. To better understand what happens to frail young people, researchers from the Research Unit of Clinical Immunology and Infant Jesus Vaccinology conducted five studies called Convers on 165 patients between the ages of 12 and 25. Studies on the efficacy of anti-Covid vaccines (some of which already published in 2021) on immunosuppressed people were conducted by researchers on 5 different categories of children and adolescents: 21 affected by primary immunodeficiency, 34 heart / lung transplanted, 30 with inflammatory bowel disease, 40 with Down syndrome and 40 with perinatal HIV infection.
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Studying the vaccine response
The response to the first two doses of the Pfizer vaccine was analyzed in the various groups, both the serological one (i.e. the amount of antibodies present in the blood) and, in 3 of the 5 groups, the cellular response (i.e. the presence of specific T lymphocytes against SARS -CoV-2 and, in the case of liver and kidney transplant recipients, B lymphocytes). The data were then compared with those of control groups composed of healthy people, subjected to the anti-Covid vaccination in the same period. All 5 studies were carried out in collaboration with the Department of Diagnostic and Laboratory Medicine and confirmed the safety of the anti-Sard-CoV-2 vaccines also for frail patients: after the administration of the doses, only transient and minor side effects.
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Fewer antibodies and lymphocytes against Sars-Cov-2
From the 5 studies it emerges that, even if the majority of immunosuppressed children respond to the vaccine they do so to a generally lesser extent than healthy subjects (fewer antibodies and fewer specific lymphocytes against Sars-CoV-2) and with differences from group to group , while a minority percentage of subjects – particularly immunocompromised – do not develop any form of immunity to the virus. “Most immunosuppressed subjects – he explains Paolo Palma, head of Clinical Immunology and Vaccinology at the Hospital of the Holy See – responds to the vaccine but to a lesser extent than healthy subjects, with differences from group to group, while a minority percentage unfortunately does not develop any form of immunity to the virus. For these frail patients it is important to intervene with a reinforcement and personalized vaccination strategy “.
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The results on patients with HIV and chronic inflammatory disease
In detail, as regards the survey on patients with perinatal HIV infection, the serological analysis found that 100% of the boys developed specific antibodies for Sars-Cov-2, but significantly lower than the average figure for the control group. . Cellular analysis, on the other hand, revealed a lack of expansion of specific T lymphocytes in 89% of cases due to the underlying inflammatory condition typical of HIV and the ability of the patient’s immune system to control it. People with chronic inflammatory disease fare better. In this case, the serological analysis showed a good response, comparable to the control group. However, in patients using anti-TNF drugs, monoclonal antibodies to treat this disease, the serological response was found to be 43% lower on average than in the group with anti-TNF-free immunosuppressive regimens. In these patients, the cause of the reduced efficacy therefore depends on the therapy they follow.
Who has Down’s Syndrome responds like an over 65
In the group of patients with Down syndrome, the researchers found a serological response in all patients, but comparable to that of adults over the age of 65. So much lower than healthy peers. A problem related to the premature aging of the immune system typical of this syndrome.
It was worse for patients with primary immunodeficiency: the serological analysis found that 14% of the boys did not develop antibodies. A good antibody response was found on the remaining 86%, but still lower than the mean of the control group. Cellular analysis instead revealed the absence of specific T lymphocytes in 24% of subjects. The reasons for the reduced effectiveness in these subjects are to be found in the malfunction of the immune system typical of this pathology.
31% of the transplant recipients did not develop antibodies
Finally, the study of children undergoing heart and lung transplantation revealed that 31% did not develop antibodies. An antibody response was recorded on the remaining 69%, but at levels significantly lower than those of the control group. Also on the cellular analysis front, the survey showed a lack of specific Sars-CoV-2 T lymphocytes in 31% of patients.
Personalized vaccination strategies
What do these results mean in practical terms? According to Bambin Gesù experts, further studies are needed to fully understand the biological mechanisms responsible for the lower vaccine response. This will allow to intervene in a personalized way for each group of frail children.
“The vaccination strategy must be adapted to the specificities of each patient group,” explains Palma. “Some groups respond better to a heterologous vaccination, others need a specific formulation, others still have to reshape the treatments they undergo and which negatively affect the effectiveness of the vaccination. Pending identification of the best vaccination strategies, doses remain fundamental. that still guarantee a valid form of protection in these categories of patients. The lower efficacy of the current anti-Sars-CoV-2 vaccines in the different types of fragile subjects also confirms the importance of vaccination for both their caregivers and the population. in general”. The fourth international conference on precision vaccination (IPVC) which will be held from 5 to 7 October 2023 in Rome, for the first time in Italy, will be in charge of vaccination in fragile patients, and which will be hosted by the Bambino Gesù in collaboration with the Harvard University and Boston Children’s Hospital.