23 Degree, Timing and Factors Observed in COVID-19 Post-Vaccination Humoral Antibody Development

Study Objective: The focus of this study was to document the timing of humoral antibody (IgM, IgG) development following SARS-CoV-2 mRNA vaccinations and assess factors influencing antibody (Ab) production. Methods: Ranging in age 23-100 years, 77 persons living or working in an assisted living facility were tested for IgG and IgM just prior to receiving their 1st dose of the Pfizer-BioNTech mRNA vaccine on 01/17/2021. Re-retesting occurred on Day 14, Day 21 (before dose 2), Day 28 and Day 42 (7 days and 21 days after dose 2). Medical histories, including underlying conditions and medications, were collected confidentially. Testing involved point-of-care lateral flow chromatography devices (under emergency use authorization as reported in our previous research on PCR+, humoral Ab- persons) using fingerstick samples. The lateral flow assay antigens included a recombinant nucleocapsid protein and a spike protein (S1) conjugated with colloid gold. Readings were recorded 15 min. after obtaining blood samples. Results: On the day of dose 1, one person had a faint IgM reading (and a known past history of COVID-19) and 3 others demonstrating detectable Ab were asymptomatic and had no known prior illness. None of these four persons were PCR + at the time of assay and their Ab profiles all further evolved following vaccination. Consistent with the original Pfizer clinical trial, on Day 14, 27 (69%) of the 39 persons 70 had no detectable Ab. However, by Day 21, just prior to receiving the second dose of vaccine, 100% of persons 90 yo, 80% tested Ab negative). Seven days after the second dose, however, 100% of persons <80 yo had become Ab positive (except 2 taking immunosuppressants). Whereas only 89% of those in their 80s (n=18) and 78% of those in their 90s had IgG detected seven days after their second dose, by day 42, only two persons remained Ab negative (one taking immunosuppressants and the other was a 93 yo). Semi-quantitative results indicated strong Ab responses for 100% of those <80 yo on Day 42. Also, as previously demonstrated, the point of care chromatography device used for the assays had reproducible results and there was persistent Ab detection in all persons once they had turned positive. Conclusions: Age and immunosuppressant conditions impact the timing and degree of Ab production following mRNA vaccination. Contrasted with our prior Ab study findings regarding native COVID-19 disease in which some persons < 50 yo manifesting milder disease do not generate IgG/IgM, the current study did demonstrate that younger persons uniformly have a rapid onset of strong IgG development after mRNA vaccination, even before their second dose. While very elderly persons and those taking immunosuppressants generally had undetectable IgG production after the first dose of vaccine, almost everyone developed strong responses, regardless of age, within a week following dose two. Antibody development became even more evident and robust 21 days after the second dose of the vaccine.