In the absence of a vaccine for COVID-19, researchers across the globe are in pursuit of possible treatments for the disease.
In a new study, researchers have established a cell culture that allows them to test antibody-laden plasma, drugs and drug combinations in the laboratory.
A screen of 136 safe-in-human antiviral drugs and identified six promising candidates.
One combination of two drugs was so effective that researchers hope others can begin clinical trials on the drugs now.
The research was conducted by a team of Norwegian and Estonian scientists.
Six months into the COVID-19 pandemic, more than 9.4 million people have been infected, and more than 470,000 have died. As yet, there is no treatment or vaccine for the disease.
In the study, the team looked at different possible treatment options—and found both good and bad news.
The good news is that the team identified six existing safe-in-humans broad-spectrum antivirals that worked against the disease in laboratory tests.
Two of the six, when combined, showed an even stronger effect in infected cell cultures.
The bad news is that another, non-drug treatment—the use of antibody-laden plasma from recovered patients to treat the severely ill—may only work if the donor has recently recovered from COVID-19.
This means if doctors collect blood from patients who have recovered from COVID-19 after two months from diagnosis of the disease, and transfuse their plasma/serum to severely sick patients, it may not help.
In the study, the team found six existing drugs that had some effect in fighting COVID-10, and several combinations of drugs that acted synergistically.
The six drugs were nelfinavir, salinomycin, amodiaquine, obatoclax, emetine and homoharringtonine.
A combination of nelfinar and amodiaquine “exhibited the highest synergy.
This last finding was encouraging enough that the researchers hope that others will follow up and start testing the drug combinations in patients.
The team also found that ordinary antibody tests may not reflect the ability of the convalescent serum to actually kill or neutralize the virus. That means the neutralization tests are still the most specific.
The neutralizing antibody tests allowed the researchers to test convalescent sera from a number of recovered patients.
They were able to see that some recovered patients didn’t produce lots of antibodies at all, a finding that has been confirmed by other research.
They also were able to see that the more recent the recovery from COVID-19, the more effective was the serum.
Two months after a patient had been diagnosed, their serum didn’t have enough antibodies to combat the virus in the cell culture.
The conclusion so far is that clinicians need to collect plasma for treatment purposes as soon as patients recover from COVID-19.
One author of the study is Magnar Bjørås, a professor in the Norwegian University of Science and Technology.
The study is published in Viruses.
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