COVID-19 is more effectively treated by a combination of drugs than singular drugs alone. The corresponding study was published in Molecular Therapy.
Patients with COVID-19 now have access to various drugs to reduce their symptom severity. Among these drugs, monoclonal antibodies are considered a first-line treatment. They work by sticking to the surface of COVID-19’s spike proteins to prevent the virus from entering human cells.
Dexamethasone is another first-line treatment and is a glucocorticoid that has been used for around 60 years for its anti-inflammatory properties. While it reduces COVID-related inflammation, it is linked to side effects, including an increased risk of fungal infection.
In the present study, researchers set out to see whether using these drugs together or individually more effectively reduces COVID-19 symptoms. To do so, they tested the drugs on hamster models of COVID-19.
After treating the hamsters, the researchers examined their lung tissue under a microscope to see the extent of lung tissue damage. They also tracked infectious virus and viral RNA levels in different tissues at various points to see whether viral activity changed over the treatment course.
While they found that antibodies reduced the amount of the virus present, it was of little aid in their model as inflammation, not the virus, damages lung tissue. However, they found that dexamethasone exerted a strong effect on neutrophils, a type of white blood cell that responds to viral and bacterial infections.
"The corticosteroid preparation suppresses the immune system and prevents the neutrophils from producing messenger substances which would attract other immune cells," said Dr. Geraldine Nouailles, Research Group Leader at Charité's Department of Infectious Diseases and Respiratory Medicine, and one of the study’s authors.
"This makes the drug extremely effective at preventing an escalation of the immune response,” she added.
In the end, the researchers found that the best treatment outcomes came when hamsters received a combination of monoclonal antibodies and dexamethasone.
"This type of combination therapy is not included in existing clinical guidelines," said Dr. Nouailles. "What is more, current guidance stipulates that, in high-risk patients, antibody therapy can only be given in the first seven days following symptom onset. In clinical practice, dexamethasone is only used once a patient requires oxygen therapy, i.e., at an extremely advanced stage of the disease. Its use in combination, however, opens entirely new treatment time windows."
The researchers say that the approach must first undergo clinical trials before being added to clinical practice.