Decay rate of antiS1/S2 IgG serum levels after 6 months of BNT162b2 vaccination in a cohort of COVID-19-naive and COVID-19-experienced subjects.

Vaccination toward SARS-CoV-2 reduced mortality and 'boosters' are being implemented. We offer scientific contribution about IgG production in the COVID-19 experienced population. From January 2021 to March 2021, 183 residents and staff from the Elderly Nursing Home "San Giuseppe Moscati" who had received two doses of the BNT162b2 vaccine were enrolled. The antibody response was assessed by the DiaSorin LIAISON-CLIA S1/S2® IgG solution. Cutoff levels for response (>39 BAU/mL) and neutralizing activity (>208 BAU/mL) were derived from DiaSorin official data. Serology was assessed before and after the first vaccination, and 2 weeks and 6 months after the second vaccination. Anti-S IgG in COVID-19 experienced, baseline IgG producers spiked after the first vaccination to median 5044 BAU/mL and decayed at 6 months to 2467.4 BAU/mL. Anti-S IgG in COVID-19 experienced, baseline IgG non-producers spiked after the second vaccination to median 1701.7 BAU/mL and decayed at 6 months to 904.8 BAU/mL. Anti-S IgG in COVID-19 naïve subjects spiked after the second vaccination to median 546 BAU/mL and decayed at 6 months to 319.8 BAU/mL. The differences between sequential timepoint levels in each group were statistically significant (p < .0001). Serology analysis revealed different kinetics between COVID-19 experienced subjects depending on baseline response, possibly predicting different IgG persistence in blood.

One-year durability of anti-spike IgG to SARS-CoV-2: Preliminary data from the anticrown prospective observational study one year durability of COVID-19 anti-spike IgG.

Data are presented of 368/503 post-COVID-19 outpatients followed within the AntiCROWN Cohort who have a one-year control and a baseline assessment of anti-S1/S2 antibodies, detected with the The LIAISON® SARS-CoV-2 S1/S2 IgG solution by DiaSorin. Loss of response occurred in 4 subjects having a baseline level below 50 AU/mL.

Short-term inhibition of SARS-CoV-2 by hydrogen peroxide in persistent nasopharyngeal carriers.

Asymptomatic and convalescent coronavirus disease 2019 (COVID-19) subjects may carry severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for months in their upper respiratory ways. Desiring to permanently clean the mucosal surfaces, we investigated the chemical agents that fit to rapidly degrade the virus. Among these, hydrogen peroxide, initially tested by two of us for tolerability, showed both good performance and acceptable side effects (burning sensation for 15-20 s). We contacted circles of family physicians and the ATS Milano (Territorial Assistance and Prevention Service), and we tested this procedure on eight persistent carriers of SARS-CoV-2, performing swabs before the procedure and after it until the reappearance of the virus or until 14 days (the incubation period), keeping the surfaces clean with a hypertonic solution. Our patients had a median time from exposure or symptom onset of 111 days, and three had relapsed after being declared "cured" (two consecutive negative swabs after quarantine). One patient had a baseline negative swab and was excluded, and two successfully ended the 14 days' course, four suppressed viral elimination for 72 h, and one for 48 h, all rebounding to weak positive (cycle thresholds above 24). Although temporarily effective, such measures may have some place in the control of viral shedding to protect the most fragile subjects.