Background. Influenza prophylaxis with the use of quadrivalent vaccines (QIV) is increasingly being introduced into healthcare practice. Methods. In total, 32 healthy adults and 6 patients with common variable immunodeficiency (CVID) received adjuvant QIV during 2018–2019 influenza season. Depending on initial antibody titers, healthy volunteers were divided into seronegative (≤1:20) and seropositive (≥1:40). To evaluate immunogenicity hemagglutination inhibition assay was used. Results. All participants completed the study without developing serious post-vaccination reactions. Analysis of antibody titer 3 weeks after immunization in healthy participants showed that seroprotection, seroconversion levels, GMR and GMT for strains A/H1N1, A/H3N2 and B/Colorado, B/Phuket among initially seronegative and seropositive participants meet the criterion of CHMP effectiveness. CVID patients showed increase in post-vaccination antibody titer without reaching conditionally protective antibody levels. Conclusion. Adjuvant QIV promotes formation of specific immunity to vaccine strains, regardless of antibodies’ presence or absence before. In CVID patients search of new regimens should be continued. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.