Do Antibody Infusions Work Against COVID-19?

artist rendition of coronavirus
See the spikes? Or are they golf tees?

A monoclonal antibody given to patients with mild COVID-19 reduced symptom severity and the odds of needing hospitalization.

About 10 days ago the hospital where I work started giving intravenous antibodies to COVID-19 patients in the emergency department. These are folks with COVID-19 symptoms and a positive COVID PCR test within the last three days but they’re not sick enough to warrant admission. My impression is that the infusion is monoclonal antibodies, different from the convalescent plasma we were offering to inpatients several months ago.

The antibody used in the study at hand is “LY-CoV555 (also known as LY3819253), a potent antispike neutralizing monoclonal antibody that binds with high affinity to the receptor-binding domain of SARS-CoV-2,” and “was derived from convalescent plasma obtained from a patient with Covid-19.” I assume scientists figured out a way to synthesize that antibody in a lab.

Click on Abstract for full details.



Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (Covid-19), which is most frequently mild yet can be severe and life-threatening. Virus-neutralizing monoclonal antibodies are predicted to reduce viral load, ameliorate symptoms, and prevent hospitalization.

This was a very small study; only a little over a hundred patients in each of three treatment groups (three different doses) and the placebo group.


In this ongoing phase 2 trial involving outpatients with recently diagnosed mild or moderate Covid-19, we randomly assigned 452 patients to receive a single intravenous infusion of neutralizing antibody LY-CoV555 in one of three doses (700 mg, 2800 mg, or 7000 mg) or placebo and evaluated the quantitative virologic end points and clinical outcomes. The primary outcome was the change from baseline in the viral load at day 11. The results of a preplanned interim analysis as of September 5, 2020, are reported here.


At the time of the interim analysis, the observed mean decrease from baseline in the log viral load for the entire population was −3.81, for an elimination of more than 99.97% of viral RNA. For patients who received the 2800-mg dose of LY-CoV555, the difference from placebo in the decrease from baseline was −0.53 (95% confidence interval [CI], −0.98 to −0.08; P=0.02), for a viral load that was lower by a factor of 3.4. Smaller differences from placebo in the change from baseline were observed among the patients who received the 700-mg dose (−0.20; 95% CI, −0.66 to 0.25; P=0.38) or the 7000-mg dose (0.09; 95% CI, −0.37 to 0.55; P=0.70). On days 2 to 6, the patients who received LY-CoV555 had a slightly lower severity of symptoms than those who received placebo. The percentage of patients who had a Covid-19–related hospitalization or visit to an emergency department was 1.6% in the LY-CoV555 group and 6.3% in the placebo group.


In this interim analysis of a phase 2 trial, one of three doses of neutralizing antibody LY-CoV555 appeared to accelerate the natural decline in viral load over time, whereas the other doses had not by day 11. (Funded by Eli Lilly; BLAZE-1 number, NCT04427501. opens in new tab

Another study looked at the use of a cocktail containing two monoclonal antibodies in non-hospitalized patients. Researchers concluded:

In this interim analysis, the REGN-COV2 antibody cocktail reduced viral load, with a greater effect in patients whose immune response had not yet been initiated or who had a high viral load at baseline. Safety outcomes were similar in the combined REGN-COV2 dose groups and the placebo group. (Funded by Regeneron Pharmaceuticals and the Biomedical and Advanced Research and Development Authority of the Department of Health and Human Services; number, NCT04425629. opens in new tab.)

Click for details.

Their report indicated that those who received the antibodies were less likely to need subsequent medical visits. But they didn’t put that in their concluding paragraph so I will assume it didn’t reach statistical significance.

Neither of these studies reported reduction in death rates.

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Obesity, particularly BMI 35 or higher, is risk factor for serious COVID-19 disease. If obese, you’ve had almost a year to work on it. How ya doin’? I can help if needed. See the book below.

Steve Parker, M.D.

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