Coronavirus antibody levels affect the risk of death from COVID-19

This photo shows a close-up of plastic bags containing plasma.

People who are hospitalized with COVID-19 and not on a ventilator have a reduced risk for death when they receive convalescent plasma with high levels of coronavirus antibodies, according to a study appearing in the New England Journal of Medicine.

The pre-planned analysis of treatment and outcome data came from 3,082 patients who were 18 years and older, hospitalized with coronavirus, and had or were progressing to severe or life-threatening COVID-19. Of the patients, 1,202 were women, 1,140 were Hispanic, and 709 were Black. The majority of patients were under age 70 and 2,014 were not undergoing ventilation before receiving convalescent plasma. Among patients, 515 received a high dose of anti-SARS-CoV-2 antibodies, 2,006 received a medium dose, and 561 received a low dose of antibodies.

The researchers found that the low dose group had the highest death rate — 66 of 561 patients (29.6%) —  within 30 days after plasma transfusion. Of the other two groups, 115 of 515 patients (22.3%) died in the high dose group and 549 of 2,006 patients (27.4%) died in the medium dose group. The study also showed a more positive outcome for patients who received convalescent plasma within three days of hospitalization. There was no effect on death for patients who were on mechanical ventilation. The study was partly-funded by NHLBI.