Three-month follow-up of durability of response to the third dose of the SARS-CoV-2 BNT162b2 vaccine in adults aged 60 years and older: a prospective cohort study. Issue 8 (2nd August 2022)

• Record Type: Journal Article
• Authors: Eliakim-Raz, Noa; Stemmer, Amos; Leibovici-Weisman, Yaara; Ness, Asaf; Awwad, Muhammad; Ghantous, Nassem; Erez, Noam; Bareket-Samish, Avital; Levy-Barda, Adva; Ben-Zvi, Haim; Moskovits, Neta; Bar-Haim, Erez; Stemmer, Salomon M
• Is Part Of: BMJ open. Volume 12:Issue 8(2022)
• Publication Date: 2022-08-02
• Subjects: COVID-19 -- EPIDEMIOLOGY -- IMMUNOLOGY; Medicine -- Research -- Periodicals; 610.72
• DOI: 10.1136/bmjopen-2022-061584
• Languages: English
• ISSNs: 2044-6055

Abstract

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.