Rapid antibody testing for SARS-CoV-2 vaccine response in pediatric healthcare workers

Background: The durability of the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination remains unknown. The objective of this study was to evaluate a rapid SARS-CoV-2 IgM/IgG antibody detection kit as a qualitative screen for the humoral response to vaccination. Methods: Study participants (n = 125) included pediatric healthcare workers (HCWs) who had received two doses of BNT162b2 or mRNA-1273. Participants were tested on study entry (March 12, 2021 to April 9, 2021). The mean number of days post second dose was 22 (range 17–36). Participants were tested for IgM/IgG antibodies to the SARS-CoV-2 spike protein with the RightSign COVID-19 IgG/IgM Rapid Test Cassette. ELISA/competitive inhibition ELISA (CI-ELISA) were subsequently run to assess for the neutralization effect and SARS-CoV-2 anti-nucleocapsid IgM/IgG antibodies. Results: Overall, 98.4% of participants were IgG-positive and 0.8% were IgM-positive on rapid RightSign testing. Of those with IgG-positive results, 100% were anti-spike protein IgG-positive on CI-ELISA; none of those who tested IgG-negative via the rapid test were IgG-positive on CI-ELISA. All HCWs who tested RightSign positive demonstrated neutralizing capability on CI-ELISA. Overall, 1.6% demonstrated anti-nucleocapsid IgM antibodies and 5.6% demonstrated anti-nucleocapsid IgG antibodies. Conclusions: The strong agreement between the rapid RightSign IgG results and confirmatory CI-ELISA testing suggests that this test may be used to assess for positive, and neutralizing, antibody responses to SARS-CoV-2 mRNA vaccination.