Durability of Humoral Responses after the Second Dose of mRNA BNT162b2 Vaccine in Residents of a Long Term Care Facility.

Alessia Lai,Pier Luigi Rossi,Fabrizio Pregliasco,Rossella Velleca,Marco D’Orso,Antonella Gatti,Annalisa Bergna,Giuseppe Calicchio,Barbara Caimi,Claudia Balotta,Marco Franzetti

doi:10.3390/vaccines10030446

Abstract

Residents of long-term care facilities (LTCFs) have been dramatically hit by the COVID-19 pandemic on a global scale as older age and comorbidities pose an increased risk of severe disease and death. The aim of the study was to assess the quantity and durability of specific antibody responses to SARS-CoV-2 after the first cycle (two doses) of BNT162b2 vaccine. To achieve this, SARS-CoV-2 Spike-specific IgG (S-IgG) titers was evaluated in 432 residents of the largest Italian LTCF at months 2 and 6 after vaccination. By stratifying levels of humoral responses as high, medium, low and null, we did not find any difference when comparing the two time points; however, the median levels of antibodies halved overtime. As positive nucleocapsid serology was associated with a reduced risk of a suboptimal response at both time points, we conducted separate analyses accordingly. In subjects with positive serology, the median level of anti-S IgG slightly increased at the second time point, while a significant reduction was observed in patients without previous exposure to the virus. At month 6, diabetes alone was associated with an increased risk of impaired response. Our data provide additional insights into the longitudinal dynamics of the immune response to BNT162b2 vaccination in the elderly, highlighting the need for SARS-CoV-2 antibody monitoring following third-dose administration.

Highlights

After the emergence of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus2), the etiologic agent of the Coronavirus Disease 19 (COVID-19) in December 2019, its global spread had caused more than 151 million cases and 1.7 million deaths by midFebruary in Europe.Italian data confirmed the association between older patient populations and highest mortality
A recent paper reported a consistent correlation between these parameters, indicating that specific antibody responses to SARS-CoV-2 are time-dependent [22]
The thresholds for positivity and cut-off values of the SARS-CoV-2 antibody provided by different assays differ, and their diagnostic value has not yet been established and standardized, its quantification after vaccination is highly relevant in identifying possible vaccine failure and estimating the level and duration of protection [24]

Summary

Introduction

Italian data confirmed the association between older patient populations and highest mortality. Risk factors for severe COVID-19 included concurrent chronic diseases typical in older age. Research findings indicated that the risk of death is significantly higher in patients with these concurrent diseases than in those who have not comorbidities. Old age increases the risk of severe COVID-19 clinical course and death [3,4]. Additional factors worsening the COVID-19 emergency within geriatric population may include intrinsic multidimensional features characterizing older subjects, such as disabilities, cognitive and mood disorders, polypharmacotherapy, social isolation, nutritional deficits and extrinsic factors detectable in widespread ageism, the generalized lack of geriatric culture and alleged errors in the management of long-term care facilities [5]

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