Impact of Prior Infection on SARS-CoV-2 Antibody Responses in Vaccinated Long-Term Care Facility Staff

Abstract

Long-term care facilities (LTCFs) have been disproportionately impacted by COVID-19, due to their communal nature, the high-risk profile of residents, and the vulnerability of residents to respiratory pathogens. In this study, we analyzed the role of prior natural immunity to SARS-CoV-2 in postvaccination antibody responses.

Magnitude and Durability of the Antibody Response to mRNA-Based Vaccination Among SARS-CoV-2 Seronegative and Seropositive Health Care Personnel

“…Our findings provide important information about the timing and resilience of the immune response, demonstrating that anti-spike SARS-CoV-2 antibody levels wane but appear to persist for most people at least 8 to 9 months and up to a year after completion of the initial vaccine series, regardless of serostatus prior to vaccination. This is consistent with studies measuring antibody responses with less frequent sampling and for shorter intervals postvaccination (up to 6 months) [ 26–28 , 40 , 45 ]. We observed a trend toward a more stable magnitude of antibody level over time postvaccination in seropositive cases as compared with seronegative ones prior to vaccination.…”

“…However, the investigators did observe significant differences at several time points and when comparing individuals vaccinated with BNT162b2 at 180 to 300 days following vaccination, as was the case for our study cohort. While our sample size of participants infected prior to vaccination is not large enough to draw definitive conclusions on antibody persistence, overall our findings appear consistent with prior data [ 14 , 28 , 40 ].…”

“…First, prior SARS-CoV-2 infection was associated with a greater magnitude of antibody response to the first dose of mRNA-based SARS-CoV-2 vaccine, even if the infection was asymptomatic or caused only mild disease. Second, while we did not note any difference in the total Ig or IgG response immediately after V 2 or V 3 among previously seropositive vs seronegative cases, neutralization did appear higher after V 2 among those who were seropositive; both findings have been observed in prior studies [ 7 , 40–42 ]. Third, when antibody responses throughout study follow-up were analyzed in aggregate, infection at any point during the study was associated with an increased magnitude of antibody levels in this vaccinated cohort.…”

“…While it is known that vaccine effectiveness against infection wanes with time from completion of the primary vaccine series [ 26 , 44–46 ], there are few studies describing the long-term durability of antibody responses to vaccination, with and without prior natural infection [ 14 , 40 ]. Our findings provide important information about the timing and resilience of the immune response, demonstrating that anti-spike SARS-CoV-2 antibody levels wane but appear to persist for most people at least 8 to 9 months and up to a year after completion of the initial vaccine series, regardless of serostatus prior to vaccination.…”

Laboratory-Based SARS-CoV-2 Receptor Binding Domain Serologic Assays Perform with Equivalent Sensitivity and Specificity to Commercial FDA-EUA Approved Tests

“…Our results confirm that detection of IgG against RBD antigens offers a sensitive and specific alternative to more cumbersome and time-consuming virus neutralization assays, whereas serologic assays based upon antibodies against nucleocapsid are less sensitive. Analysis of nucleocapsid antibodies can, however, assist in distinguishing individuals that have experienced COVID-19 infection versus those vaccinated with mRNA RBD preparations [ 23 ]. In lab, testing focused on spike and RBD recombinant proteins yielding higher sensitivity.…”