213 Age Differences among Persons With Positive COVID-19 Molecular Testing Later Testing Negative for Antibodies to SARS-CoV-2

Study Objectives: Controversies exist regarding both the accuracy and value of SARS CoV-2 antibody (Ab) testing, particularly when those with prior + molecular testing (PCR+) are later Ab-, or those testing Ab+ are PCR- While PCR test timing, delays, technique and assays might (in part) explain PCR-/Ab+ (beyond simple \"false+\"), PCR+/Ab- explanations range from inadequate assays/techniques to transient, entirely absent, or delayed Ab responses However, prior observations of other corona viruses (eg, MERS-CoV) have paradoxically indicated undetectable Ab among younger infected persons, particularly those with milder illness The objective here was to determine if significant age or illness severity differences did exist among COVID-19 PCR+ persons later testing Ab negative, specifically comparing 2 different manufacturers\u0027 assays in two dissimilar U S cities Methods: In step 1 of an ongoing study, 2 EMS agencies (1 fire, other 3rd service) in 2 well-distanced U S cities with different populations, evaluated PCR+ employees with subsequent (later date) IgM/IgG testing, each respectively using 2 different lateral flow chromatographic immunoassay (LFCIA) products Among 70 volunteering at Site 1, 39 were selected as a reference group from the general population with no prior COVID-19 symptoms or testing (Sx-/NoPCR group) The other 31 (PCR+) principals had +nasal swab tests obtained between late March and end of April 2020 (for exposures or Sx) On May 9, all 70 received testing for IgM/IgG using a fingerstick (FS) LFCIA along with simultaneous venipuncture specimens (later demonstrating identical IgM/IgG congruence in the 140 samplings) At Site 2, using the other LFCIA product, 17 PCR+ persons also had FS IgM/IgG testing Participants were surveyed (both sites) for pre-selected Sx categories, illness severity indicators, age, sex \u0026 date of PCR+ test or Sx onset Results: The Sx-/NoPCR reference group (n=39;mean age 45 51 yrs, range 26-75;59% women) all tested negative for both IgG \u0026 IgM For the Site 1 PCR+ group (n=31, mean age 41 5 yrs, range 21-81;52% women), only 67 7% (n=21) were Ab+ Similar to the reference group, the PCR+/Ab+ subgroup mean age was 44 7 yrs (21-81 yrs) with 57% women (p=NS) However, among the 10 (32 3%) with prior PCR+ tests but no IgM/IgG, the mean age was 34 7 yrs (range 21-50) with only 40% women Compared to either PCR+/Ab+ (n=21) or the reference group (also Ab-), age differences were significant (two-tailed, p=0 048 \u0026 0 021, respectively) Strikingly similar, even using a different assay in a different population, 5 (29 4%) of the 17 PCR+ persons at Site 2 were also Ab- with mean ages 32 2 (27-39) vs 42 75 yrs (25-62) for the 12 Ab+ persons (p=0 048) Combining both sites, mean ages for PCR+/Ab- (n=15) vs PCR+/Ab+ (n=33) were 33 93 vs 43 97 (p=0 0089) Comparing PCR+/Ab- age vs the reference group, p=0 0028 (Table) At both sites, trends were evolving between Ab- and milder disease, women and shorter PCR to Ab testing intervals Conclusion: Using different IgM/IgG LFCIA products in different ecological settings, 30% of persons with prior COVID-19 PCR+ tests were Ab- at both locations and, in either venue, those PCR+/Ab- persons were significantly younger than PCR+/AB+ counterparts [Formula presented]