Convalescent immunoglobulins (IgG) are superior to convalescent plasma as treatment for COVID-19 infection, according to study results published in Clinical Infectious Diseases.

This randomized, controlled, open-label, phase 2, noninferiority study was conducted between January and November 2021 at Wolfson Medical Center in Israel. Researchers randomly assigned patients 1:1 to receive either 4 g of intravenous convalescent IgG (n=166) or 2 high-titer units (200 mL) of convalescent plasma (n=153), administered over 2 consecutive days. Eligible patients were adults hospitalized with laboratory-confirmed COVID-19 infection who had symptoms for 10 days or less. All patients had lung infiltrates and an oxygen saturation below 95% on room air.

The primary efficacy endpoint was the number of patients who scored at least 2 points higher than baseline by day 14 on the World Health Organization’s (WHO) 8-point ordinal clinical severity scale. Scores were assessed on the first day of treatment and again at days 7, 14, and 28. Noninferiority was calculated using a margin of 10%, and the superiority of convalescent IgG over convalescent plasma was assessed via Fisher exact testing.

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Among patients in the convalescent IgG and plasma groups, the median ages were 64 (range, 20.0-95.0) and 66 (range, 28.0-97.0) years, 46.9% and 39.2% were women, 60.8% and 53.3% had hypertension, and 41.6% and 40.5% were unvaccinated, respectively. In addition, the median time from symptom onset to treatment (range, 6-7 days) and median WHO 8-point ordinal scale scores at baseline (range, 5-5.1) were similar between the groups.  

[I]n the face of new variants cIgG is a viable option for treating COVID-19 patients.

At day 14, more patients in the convalescent IgG group reached the primary efficacy endpoint than those in the convalescent plasma group (67.5% and 67.3%, respectively), though the between-group difference was noninferior (0.1%; 95% CI, -10.1 to 10.4; P =.026). However, at day 28, the percentage of patients in the convalescent IgG vs plasma group who reached the primary efficacy endpoint was both higher (81.9% vs 70.6) and indicated superiority (Difference, 11.3%; 95% CI, 1.9-20.7; P <.001; P for superiority =0.018).

Further analysis showed that the number of patients who required mechanical ventilation was lower among those who received convalescent IgG vs plasma (10.2% vs 16.3%; P =.136). Patients in the convalescent IgG group also had lower 14-day mortality rates (9.6% vs 15%; P =.172), though the median time to hospital discharge was 7 days for both groups.

In unvaccinated patients, the effect of convalescent IgG was greater than that of convalescent plasma, reaching superiority and showing significantly increased survival benefit by day 28. However, in vaccinated patients, receipt of convalescent IgG vs plasma was neither superior nor associated with increased survival benefit.   

Limitations of this study include that treatment was administered up to 10 days after symptom onset, as well as the possibility that some patients were in the inflammatory state of COVID-19 infection.

“[I]n the face of new variants cIgG [convalescent IgG] is a viable option for treating COVID-19 patients,” the researchers noted. “Further studies are warranted to assess cIgG earlier in the course of disease,” they concluded.

Disclosure: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

This article originally appeared on Infectious Disease Advisor