Complete (Humoral and Cellular) Response to Vaccination against COVID-19 in a Group of Healthcare Workers-Assessment of Factors Affecting Immunogenicity

Abstract

Vaccination is the best way to limit the extent of the COVID pandemic. Knowledge of the duration of the immune response will allow the planning of a vaccination protocol. This study aims to validate the complete (humoral and cellular) immune responses over time in large population groups following the full vaccination of healthcare professionals in real-life conditions and to assess the relationship between antibody levels and T-cell activity in relation to the characteristics of the study group. The samples for the study were obtained from volunteers (staff of two hospitals) on three occasions: before vaccination, T0, then 4–9 weeks after full vaccination (two doses BNT162b2), T1, and 7–9 months after vaccination, T2. The humoral response was investigated by the titre of anti-SARS-CoV-2 IgG antibodies to S1 protein. Assays were performed three times at intervals. The cellular response was assessed in a subgroup of 189 subjects by QuanT-Cell SARS-CoV-2 (IGRA). The assay was performed once. A group of 344 subjects fully vaccinated with the BNT162b2 vaccine were included in the study. The humoral response was observed in 100% of subjects at both 4–7 weeks and 7–9 months, but antibody titres fell by almost 90% in this interval. The cellular response was observed in 94% (177/189) of subjects 7–9 months after the second dose of vaccine. In subjects with a negative cellular response, eight out of 12 smoked. A factor associated with greater immunogenicity of vaccination was past SARS-CoV-2 infection. The administration of full BNT162b2 vaccination (two doses) induces humoral and cellular responses detectable even more than six months after vaccination. Smoking may be a factor associated with impaired cellular response to vaccination.

Durability of humoral and cell‐mediated immune response after SARS‐CoV‐2 mRNA vaccine administration

“…Several authors note that the levels of specific anti‐SARS‐CoV‐2 antibodies gradually and significantly decrease 6–8 months after the second dose of mRNA vaccines. 8 , 9 , 10 , 11 , 12 The emergence of new viral variants of concern and their rapid spread worldwide has led to new questions regarding the administration of booster doses of vaccines to restimulate the immune response. However, the question of how durable immunity to SARS‐CoV‐2, whether and when it should be tested, remains open.…”

“…A number of studies followed in 2021 and early 2022 on the onset, profile, kinetics, and persistence of the humoral and cell‐mediated immune response in both COVID‐19 survivors and vaccinees. Several authors note that the levels of specific anti‐SARS‐CoV‐2 antibodies gradually and significantly decrease 6–8 months after the second dose of mRNA vaccines 8–12 . The emergence of new viral variants of concern and their rapid spread worldwide has led to new questions regarding the administration of booster doses of vaccines to restimulate the immune response.…”

Immune Cells Profiles In The Peripheral Blood Of Patients With Moderate To Severe COVID-19 And Healthy Subjects With and Without Vaccination With The Pfizer-BioNTech mRNA Vaccine

“…The pre-existing T cells in recovered patients was found to correlate with a better cellular and humoral response following mRNA vaccination ( 33 ). Thus, it would be interesting to study the duration of the protective response induced following vaccination in the recovered vs the infection-naïve subjects ( 33 ) as BNT162b2 is the first mRNA vaccine used on a large scale ( 34 ).…”

Immunity after COVID-19 Recovery and Vaccination: Similarities and Differences

“…In a study of 2653 BNT162b2-vaccinated subjects, antibody titers decreased by up to 38% each subsequent month, and at six months after vaccination 16.1% subjects presented antibody levels below the seropositivity threshold [ 118 ]. The study involving 344 medical personnel vaccinated with two doses BNT162b2 showed that antibody titers fell by almost 90% within 7–9 months after vaccination [ 119 ].…”