Beijing: Researchers have reviewed the existing potential treatment approaches against the novel coronavirus behind the COVID-19 pandemic, noting that drugs directly targeting the virus are likely to be most effective.
According to the research, published in the journal Antimicrobial Agents and Chemotherapy, a number of potential therapeutic approaches for the treatment of COVID-19 is growing, including blocking the virus (SARS-CoV-2) from entering cells, disrupting its replication, suppressing overactive human immune response, and vaccines.
However, the scientists, including those from Wuhan University in China, said no drug or vaccine has been officially approved due to the absence of adequate evidence.
Assessing earlier studies on the virus, they said SARS-CoV-2 is easily transmissible due to the spike proteins on its surface which bind efficiently to the molecule "angiotensin-converting enzyme 2" (ACE2) on the surfaces of human cells.
"Cell entry is the first step of cross-species transmission. SARS-CoV-2 is more likely to infect lung type II alveolar cells, which may explain the severe alveolar damage after infection," the scientists wrote in the research.
The study noted that a pilot clinical trial is underway in patients with severe COVID-19, investigating use of genetically modified human ACE2 to act as "decoys" that would attach to spike proteins, disabling SARS-CoV-2's mechanism for entry into human cells.
As of now, the researchers said, the most promising antiviral for fighting SARS-CoV-2 is remdesivir.
They said the drug gets incorporated into nascent viral RNA, where it prevents RNA synthesis, and in turn, further viral replication.
Remdesivir, according to the study, inhibited SARS-CoV-2 replication in laboratory studies.
It also noted that the clinical condition of the first confirmed case of COVID-19 in the US improved following intravenous remdesivir administration.
However, they said more data on its effectiveness is needed.
The scientists also noted that Tilarone, a broad spectrum antiviral, may also be active against SARS-CoV-2.
They said the 50-year-old synthetic small molecule is used in some Russian Federation countries and neighbouring countries against multiple viruses, including acute respiratory viral infection, influenza, and hepatitis.
Based on earlier research, the study noted, Tilarone is also active against chikungunya and MERS-CoV viruses.
While tilarone is approved in Russian Federation countries, the researchers said, it has not been tested for safety and efficacy in studies that meet the US Food and Drug Administration standards.
Another approach the study mentioned is the transfusion of blood from recovered patients -- which contain antibodies against the virus -- into current patients.
But due to the lack of high quality clinical trials and knowledge of the precise mechanism of action, the researchers said, it is not clear how effective this therapy is, and is used mainly in patients in critical condition.
Several clinical trials investigating its effectiveness and safety against COVID-19 are underway, they added.
The study also said there are over fifteen vaccine candidates currently under development around the world, with each taking a different approach to vaccine design -- all of which may take approximately 12-18 months for completion.
"Among these options, we suppose the therapeutic drugs that directly target SARS-CoV-2 will be most effective. Besides, vaccines are critical for the prevention and limitation of COVID-19 transmission, " the researchers concluded in the study.