Humoral immunity induced by mRNA COVID-19 vaccines in Nursing Home Residents previously infected with SARS-CoV-2

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

Few studies have described changes in SARS-CoV-2 antibody levels in response to infection and vaccination at frequent intervals and over extended follow-up periods. The purpose of this study was to assess changes in SARS-CoV-2-specific antibody responses among a prospective cohort of health care personnel over 18 months with up to 22 samples per person. Antibody levels and live virus neutralization were measured before and after mRNA-based vaccination with results stratified by (1) SARS-CoV-2 infection status prior to initial vaccination and (2) SARS-CoV-2 infection at any point during follow-up. We found that the antibody response to the first dose was almost 2-fold higher in individuals who were seropositive prior to vaccination, although neutralization titers were more variable. The antibody response induced by vaccination appeared to wane over time but generally persisted for 8 to 9 months, and those who were infected at any point during the study had slightly higher antibody levels over time vs those who remained uninfected. These findings underscore the need to account for SARS-CoV-2 natural infection as a modifier of vaccine responses, and they highlight the importance of frequent testing of longitudinal antibody titers over time. Together, our results provide a clearer understanding of the trajectories of antibody response among vaccinated individuals with and without prior SARS-CoV-2 infection.

Polypharmacy and Antibody Response to SARS-CoV-2 Vaccination in Residents of Long-Term Care Facilities: The GeroCovid Vax Study

BACKGROUND AND OBJECTIVE

Polypharmacy is common in older adults, particularly among those living in long-term care facilities. This condition represents a marker of clinical complexity and might directly affect the immunological response. However, there are limited data on the association of polypharmacy with vaccine immunogenicity. This study evaluated the immune response to anti-SARS-CoV-2 vaccines in older residents of long-term care facilities as a function of the number of medications used.

METHODS

In 478 long-term care facility residents participating in the GeroCovid Vax study, we assessed SARS-CoV-2 trimeric S IgG levels through chemiluminescent assays before the vaccination and after 2, 6, and 12 months. A booster dose was administered between 6- and 12-month assessments. Sociodemographic information and data on chronic diseases and medications were derived from medical records. Based on the number of daily medications, residents were classified into the no polypharmacy (zero to four medications), polypharmacy (five to nine medications), and hyperpolypharmacy (ten or more medications) groups.

RESULTS

In the sample (mean age 82.1 years, 69.2% female), 200 (41.8%) residents were taking five or fewer medications/day (no polypharmacy), 229 (47.9%) had polypharmacy, and 49 (10.3%) had hyperpolypharmacy. Using linear mixed models adjusted for potential confounders, we found that hyperpolypharmacy was associated with a steeper antibody decline after 6 months from the first vaccine dose administration (β = - 0.29, 95% confidence interval - 0.54, - 0.03, p = 0.03) than no polypharmacy, while no significant differences were observed at 12 months.

CONCLUSIONS

The humoral immune response to SARS-CoV-2 vaccination of older residents showed only slight changes as a function of the number of medications taken. Although it seemed less durable among older residents with hyperpolypharmacy, the booster dose administration equalized such a difference.

Evaluation of humoral and cellular response to four vaccines against COVID-19 in different age groups: A longitudinal study

To date there has been limited head-to-head evaluation of immune responses to different types of COVID-19 vaccines. A real-world population-based longitudinal study was designed with the aim to define the magnitude and duration of immunity induced by each of four different COVID-19 vaccines available in Italy at the time of this study. Overall, 2497 individuals were enrolled at time of their first vaccination (T0). Vaccine-specific antibody responses induced over time by Comirnaty, Spikevax, Vaxzevria, Janssen Ad26.COV2.S and heterologous vaccination were compared up to six months after immunization. On a subset of Comirnaty vaccinees, serology data were correlated with the ability to neutralize a reference SARS-CoV-2 B strain, as well as Delta AY.4 and Omicron BA.1. The frequency of SARS-CoV-2-specific CD4+ T cells, CD8+ T cells, and memory B cells induced by the four different vaccines was assessed six months after the immunization. We found that mRNA vaccines are stronger inducer of anti-Spike IgG and B-memory cell responses. Humoral immune responses are lower in frail elderly subjects. Neutralization of the Delta AY.4 and Omicron BA.1 variants is severely impaired, especially in older individuals. Most vaccinees display a vaccine-specific T-cell memory six months after the vaccination. By describing the immunological response during the first phase of COVID-19 vaccination campaign in different cohorts and considering several aspects of the immunological response, this study allowed to collect key information that could facilitate the implementation of effective prevention and control measures against SARS-CoV-2.