Immunological Response in HIV-Positive Patients Vaccinated against Tick-Borne Encephalitis

Abstract.

Background: Vaccination against infectious diseases is a recommended preventive measure in patients with impaired immunity. The aim of the study was to estimate the immunogenicity of the vaccine against tick-borne encephalitis (TBE) in HIV-infected patients and to determine its safety for this group.

Patients and Methods: The TBE vaccine FSME-IMMUN-inject was tested on 29 HIV-positive patients and the response compared to that of 40 healthy controls. The vaccination protocol for the HIV-positive group was modified by the addition of a fourth dose according to a 0/1/2/9-month schedule.

Results: No serious adverse reactions were observed in patients with deficient immunity. A better response was obtained in HIV-infected patients with CD4 counts ≥ 500/μl (55% of the patients had levels of IgG antibody > 126 VIEU/μl) than in those with CD4 counts of 200–499/μl (40%). However, the difference did not reach significance. 85% of healthy controls achieved protective antibody titers after a full course of vaccination.

Conclusion: The correlation between post-vaccine seroconversion and CD4 lymphocyte count showed that the FSME-IMMUN-inject vaccine can be considered to be a CD4 cell-independent vaccine. The examinations carried out 1 year after the completed vaccination protocol showed maintenance of the anti-TBE response acquired after the third vaccination in healthy subjects and in HIV-infected patients.