COVID-19 Neutralizing Antibody Surveillance Testing for Fully Vaccinated Individuals During Delta Variant Spread

We recently performed 568 rapid neutralizing antibody (NAb) tests on 164 fully vaccinated individuals who received either Moderna or Pfizer COVID-19 vaccine regimens over 7 weeks. The NAb levels against the wild type (WA1/2020), Delta, and Kappa variants were measured and compared. Depending on each individuals medical condition and vaccination status, the NAb levels for most of the fully vaccinated people decreased within 2-6 months, while a small number of individuals either generated non-detectable amount of NAbs after full vaccination (e.g., immunocompromised), or had high NAb levels lasting beyond 6 months. Since the NAb levels vary significantly among different individuals and decrease over time, the deployment of a low-cost rapid test to monitor NAb levels against both the wild type and emerging variants among fully vaccinated individuals can play a very crucial role to control the current pandemic. Our study provides an example of using such a rapid NAb test to fill this currently unmet medical need.