Abstract
Purpose: Clinical significance and durability of serological response after mRNA COVID-19 vaccines is under investigation. Data on early virological response are limited. To iden-tify potential predictors of antibody durability, circulating antibody levels were longitudinally ex-plored in healthcare workers included in a follow-up program for SARS-CoV-2 infection. Meth-ods: Subjects meeting the inclusion criteria signed an informed consent. Serum samples were col-lected at baseline, before the first BNT162b2 vaccine, at days 7, 21, 31, 90, and 180 days after the first dose. Serological evaluation was performed by QuantiVac Euroimmune anti-S1 antibody as-say. Only subjects followed-up until day 90 are here considered. Results: Of 340 taken into consid-eration, 265 subjects were naive, and 75 COVID-19 experienced. The former showed a progres-sive increase in their antibody levels before day 90 decline, while the latter showed antibody levels reaching a plateau at day 7 and slightly declining at day 90. All showed antibody levels higher than the assay cut-off at day 31 and 90. Among naive, 108 had an early response whose predic-tors were younger age and female gender (OR 0.94, 95% CI 0.91–0.96, p < 0.0001; and OR 2.58, 95% CI 1.48–4.51, p = 0.0009). Naive subjects experienced a day 30/90 decline in antibody levels, whereas experienced did not. Early response was an independent predictor of higher day 30/90 antibody levels decline (OR = 2.05, 95% CI 1.04–4.02; p = 0.037). Conclusions: Our results suggest that in healthcare workers early response might be inversely associated with antibody levels 90 days after BNT162b2 vaccine.
Highlights
SARS-CoV-2 virus infection was declared a Public Health Emergency by World HealthOrganization (WHO) on 30 January 2020 and has currently led up to over 3.72 million deaths globally [1]
Since neutralizing antibody response is difficult to investigate in large real-life series, kinetics of antibody response and information about its strength and durability after vaccination in persons with or without history of COVID-19 infection might help in orienting future vaccination strategies
After a careful analysis of the swab test results, 71 (19.6%) COVID-experienced symptomatic subjects were identified. This rate is in keeping with the decision of our Institution to include subjects with a previous COVID-19 infection in the vaccination campaign
Summary
SARS-CoV-2 virus infection was declared a Public Health Emergency by World HealthOrganization (WHO) on 30 January 2020 and has currently led up to over 3.72 million deaths globally [1]. Available data regarding vaccine efficacy are derived by phase III studies on the approved vaccines with established schedules for BNT162b2 mRNA day 1 and day 21 vaccine administration, and by real-world Israeli experience [4,5]. It has been hypothesized that, as adopted in UK for AstraZeneca vaccine, a single dose of BNT162b2 vaccine may be suited to these subjects. This is corroborated by recent studies demonstrating that immune memory involving all four major types of response—i.e. antibodies, memory B cells, memory CD8+ T cells, and memory CD4+ T cells—is measurable in 95% of subjects up to 5 to 8 months post symptoms onset [11,12]. Limited data on early humoral response are currently available [14,15]
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