Therapies to interrupt progression of early COVID-19 remain elusive. Among them, convalescent plasma in hospitalized patients was unsuccessful, perhaps because antibody should be administered earlier. A randomized, double-blind, placebo-controlled trial of convalescent plasma with high IgG titers against SARS-CoV2 in elderly subjects within 72 hours of mild COVID-19 symptoms. The primary endpoint was severe respiratory disease defined as a respiratory rate ≥30 and/or an O2 sat<93% in room air. 160 patients underwent randomization. In the intention-to-treat analysis (ITT), 13/80(16.2%) patients receiving plasma vs. 25/80(31.2%) receiving placebo experienced severe respiratory disease [RR(95%CI)= 0.52(0.29,0.94); p=0.026)] with an RRR=48%. High- and low-titer donor analyses, based on a median IgG titer=1:3,200, evidenced a dose-dependent response with an RRR=73.3% for recipients of high-titer plasma (p=0.016) and a number needed to treat (NNT)=4.4. All secondary endpoints exhibited trends towards protection. No solicited adverse events were observed. Early administration of high-titer convalescent plasma against SARSCoV2 to mildly ill infected seniors reduced COVID-19 progression.

In this repeated, cross-sectional study of 177 919 residual clinical specimens, the estimated percentage of persons in a jurisdiction with detectable SARS-CoV-2 antibodies ranged from fewer than 1% to 23%. Over 4 sampling periods in 42 of 49 jurisdictions with calculated estimates, fewer than 10% of people had detectable SARS-CoV-2 antibodies.

In this study, A total of 228 patients were assigned to receive convalescent plasma and 105 to receive placebo. The median time from the onset of symptoms to enrollment in the trial was 8 days (interquartile range, 5 to 10), and hypoxemia was the most frequent severity criterion for enrollment. The infused convalescent plasma had a median titer of 1:3200 of total SARS-CoV-2 antibodies (interquartile range, 1:800 to 1:3200]. At day 30 day, no significant difference was noted between the convalescent plasma group and the placebo group in the distribution of clinical outcomes according to the ordinal scale (odds ratio, 0.83 (95% confidence interval [CI], 0.52 to 1.35; P=0.46). Overall mortality was 10.96% in the convalescent plasma group and 11.43% in the placebo group, for a risk difference of −0.46 percentage points (95% CI, −7.8 to 6.8). Total SARS-CoV-2 antibody titers tended to be higher in the convalescent plasma group at day 2 after the intervention. Adverse events and serious adverse events were similar in the two groups.