NCT05365750

COVID-19 Antibody and Reinfection Study

Completed Results posted Last updated 18 September 2025

What this trial tests

trial in COVID-19 Testing in 4,235 participants. Completed in 31 December 2024.

Timeline

15 June 2020

Primary endpoint
30 March 2023

31 December 2024

Quick facts

Lead sponsor	Kaiser Permanente
Status	Completed
Study type	OBSERVATIONAL
Enrollment	4,235
Start date	15 June 2020
Primary completion	30 March 2023
Estimated completion	31 December 2024
Sites	1 location across United States

Conditions studied

• COVID-19 Testing — all drugs for COVID-19 Testing →

Sponsor

Kaiser Permanente — full company profile →

Who can join

18 and older, any sex, with COVID-19 Testing. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Reinfection With SARS-CoV-2 Primary · Through the completion of the study analytic period, an average of 6 months

In this case-control analysis, case patients were participants with the outcome of reinfection. The date of reinfection was the index date. Control patients were those with a primary infection but without the outcome reinfection by the index date. The case and control participants were compared with respect to a seronegative test result (exposure) after primary infection and closest in time to the index date. Because the cases and controls were selected on the basis of the outcome, the seronegative result is listed below by case and control status.

Group	Value	95% CI
Case Patients	12
Control Patients	77
Case Patients	68
Control Patients	957

Sponsor's own description

The goal of this study is to establish a cohort of Kaiser Permanente Colorado (KPCO) members who have and have not had COVID-19 infection for serial antibody testing and PCR testing to:

1. Quantify antibody titers among participants over 9 months.
2. Determine the rates of asymptomatic, mild, and severe recurrent infection among participants with prior COVID-19.
3. Examine association between antibody titer levels and risk of recurrent infection using a case control analysis nested in the cohort.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Association between severe acute respiratory syndrome coronavirus 2 antibody status and reinfection: A case-control study nested in a Colorado-based prospective cohort study.
   Binswanger IA, Narwaney KJ, Barrow JC, Albers KB, et al · · 2024 · cited 2× · PMID 38205171 · DOI 10.1016/j.pmedr.2023.102530