In the search to find a treatment for COVID-19, drugs which have previously been developed to treat other viral infections are being tested to see if they might also be effective against SARS-CoV-2, the virus that causes COVID-19. We spoke to Dr Daman Langguth, Clinical Immunologist at Sullivan Nicolaides Pathology to discuss the effectiveness of some of these.
“There are two approaches; you either try and stop the virus or you try to stop the immune response to the virus. Stopping the virus is obviously an attractive option, however this can only be achieved with a vaccine, which is very complex for these types of viruses. A great drug would stop everyone who went into hospital from going into intensive care.
“So far, there is no good evidence that any approach reduces the risk of progression from mild to severe disease. According to preliminary findings, dexamethasone, which is a corticosteroid, has been shown to increase survival for patients on ventilators, however, is only useful in patients with moderate to severe disease. Data sets suggest that use of dexamethasone prior to contracting COVID-19 may put people at greater risk. In addition, antiviral drug remdesivir has been shown to decrease time in ICU for those with severe COVID-19,” said Dr Langguth.
Hydroxychloroquine (HCQ) gained much media attention after early results from studies in France and China showed promising signs of the drug working against COVID-19. Since then, debate has remained about the effectiveness of HCQ on patients who have the disease, and on 17th June 2020 the World Health Organisation (WHO) announced that it was suspending this arm of its trial.
HCQ is a medicine used to treat rheumatoid arthritis and other inflammatory conditions such as systemic lupus erythematosus (SLE/Lupus). It is also an antimalarial medicine used to prevent and treat malaria and other parasitic infections. More work is still needed to see whether HCQ may be effective as a preventative medicine.
“The use of HCQ in the prophylaxis and treatment of COVID-19 looked in vitro and was conceptually interesting in the beginning, however human studies suggest that there is no benefit of HCQ and possibly a higher risk of death due to lethal heart rhythm abnormalities. There is limited data supporting its efficacy in COVID-19 as well as considerable concern about its safety when used at high doses (>400 mg daily) and in combination with other QT interval prolonging drugs,” said Dr Langguth.
Recently, antiviral drug remdesivir received provisional approval from the Therapeutic Goods Administration (TGA), making it Australia’s first treatment option for people severely ill with COVID-19. Remdesivir was previously tested as an Ebola treatment. It has generated promising results in animal studies for Middle East Respiratory Syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS), which are also caused by coronaviruses, suggesting it may have some effect in patients with COVID-19.
Remdesivir is one of the most promising treatments so far to reduce hospitalisation time in those patients with severe COVID-19 symptoms.
“This provisional approval by the TGA means that remdesivir can now be used in hospitals under strict controls and supervision. It will be available to adults and adolescents in hospital with severe infections who need oxygen or are on respirators. It is hoped that this will reduce the strain on Australia’s health care system by reducing recovery time for those patients suffering with severe COVID-19,” said Dr Langguth.
In a statement, the TGA stressed that while this is a major milestone in Australia's struggle against the pandemic, it is important to emphasise that the product has not been shown to prevent coronavirus infection or relieve milder cases of infection.