Evaluating length of immune response to SARS-CoV2 vaccine: A cohort review of spike protein antibody titer after vaccination

Background

The SARS-CoV2 pandemic required rapid development and expedited evaluation of vaccine efficacy. Initial evidence suggested waning immune response to SARS-CoV2 vaccination steadily over the first six months. This study evaluated duration of immunity in vaccinated patients at a single tertiary center in New York City during the pandemic.

Methods

We conducted a retrospective review of adult vaccinated patients admitted over a period of 3 months during the SARS-CoV2-Omicron variant and evaluated their immune response using the spike protein antibody titer. A total of 2476 patients were screened, and 1875 patients were included in the study. Secondary analysis of a cohort of patients with COVID-19 disease was also performed.

Results

Spike protein antibody was positive in 99 % of patients. Most patients received two doses of the Pfizer (42 %) or the Moderna (27 %) vaccines. There was a negative correlation between months since vaccination and spike protein antibody titer (Spearman's rank correlation –0.094, p <0.0001). Subgroup analysis of those who had received at least two doses of a vaccine series revealed similar negative correlations for both Pfizer (Spearman's rank correlation –0.14, p <0.0001) and Moderna vaccines (Spearman's rank correlation –0.11, p = 0.0043). Secondary analysis of patients admitted with a diagnosis of COVID-19 infection did not demonstrate any statistically significant difference in titer results over time.

Conclusions

Our study of patients admitted to a tertiary care center across a diverse patient population demonstrated that patients who were vaccinated against SARS-COV2 had a robust response in their spike protein antibody titer which was maintained well beyond six months after vaccination.