Abstract
Objective: To evaluate the durability of response 3 months after the third BNT162b2 vaccine in adults aged 60 years and older.
Design: Prospective cohort study.
Setting: Single tertiary centre.
Participants: Healthcare workers/family members aged ≥60 years old who received the third BNT162b2 dose.
Interventions: Blood samples were drawn immediately before (T0), 10-19 days (T1) and 74-103 days (T2) after the third dose.
Primary and secondary outcome measures: Anti-spike IgG titres were determined using a commercial assay and seropositivity was defined as ≥50 arbitrary units (AU)/mL. Neutralising antibody titres were determined at T2. Adverse events, COVID-19 infections and Clinical Frailty Scale (CFS) levels were documented.
Results: The analysis included 97 participants (median age, 70 years (IQR, 66-74), 58% CFS level 2). IgG titres, which increased significantly from T0 to T1 (median, 440 AU/mL (IQR, 294-923) and median, 25 429 AU/mL (IQR, 14 203-36 114), respectively; p<0.001), decreased significantly by T2, but all remained seropositive (median, 8306 AU/mL (IQR, 4595-14 701), p<0.001 vs T1). In a multivariable analysis, only time from the second vaccine was significantly associated with lower IgG levels at T2 (p=0.017). At T2, 60 patients were evaluated for neutralising antibodies; all were seropositive (median, 1294 antibody titres; IQR, 848-2072). Neutralising antibody and anti-spike IgG levels were correlated (r=0.6, p<0.001). No major adverse events or COVID-19 infections were reported.
Conclusions: Anti-spike IgG and neutralising antibody levels remain adequate 3 months after the third BNT162b2 vaccine in healthy adults aged ≥60 years, although the decline in IgG is concerning. A third dose of vaccine in this population should be top priority.
Keywords: COVID-19; EPIDEMIOLOGY; IMMUNOLOGY.
【저자키워드】 COVID-19, Epidemiology, immunology., 【초록키워드】 IgG, Vaccine, BNT162b2 vaccine, antibody, cohort study, BNT162b2, COVID-19 infection, neutralising antibody, clinical, Prospective, adverse event, Patient, scale, seropositive, Antibody titre, Analysis, dose, Older, Adverse, titres, median age, blood sample, multivariable analysis, participant, secondary outcome, titre, CFS, neutralising, defined, evaluate, significantly, healthy, reported, remained, evaluated, events, median, correlated, concerning, anti-spike IgG level, arbitrary unit, IgG level, IQR, 【제목키워드】 BNT162b2 vaccine, prospective cohort study, Follow-up, dose, the SARS-CoV-2,