A widely available and affordable blood-thinning drug, heparin, limits lung damage when inhaled by COVID-19 patients, and may also prevent infection from the SARS-CoV-2 virus, according to early results of a study. 

Researchers from the Australian National University (ANU) and colleagues are tracking hospital patients infected with SARS-CoV-2 in 13 countries who were given doses of inhaled heparin. The initial results from 98 patients, published in the British Journal of Clinical Pharmacology, indicate that heparin could be a promising treatment and also a possible preventative against the virus.

The researchers found that breathing and oxygen levels improved in 70 per cent of the patients after they inhaled a course of heparin, and their symptoms improved according to the WHO COVID symptoms scale. They, however, cautioned that larger studies are needed to confirm heparin as a preventive or treatment option for COVID-19.

"There is still an urgent need for an effective treatment of COVID-19 and the early results of our trials show inhaled heparin is safe and effective," said study lead Professor Frank van Haren from ANU. "This drug is already available in hospitals all over the world and it is a very inexpensive drug. If it is as effective as our early results suggest, it could have a major impact on our fight against COVID," Van Haren said.

Heparin, which is normally administered via injection, is a blood thinner used to treat and prevent blood clots across the world and is widely available." Inhaled heparin has antiviral properties which work by binding to the spike proteins the coronavirus uses to enter the cells of the body," said Professor Clive Page, from King's College London in the UK, who is co-leading the global studies.

"Inhaled heparin effectively stops the virus infecting cells in the lungs and could also stop people from getting the virus from others, Page said. The researchers noted that heparin also works as an anti-inflammatory drug with the ability to calm down the body when it is mounting an exaggerated response to the virus.

"We already know heparin can reduce lung damage caused by this inflammation and the immune response overdrive that we see in other lung diseases which could provide benefit to patients hospitalised with COVID-19," said Page. Researchers noted that when COVID-19 patients get very sick they develop blood clots in the lungs and these can be lethal. Heparin, being a blood-thinner, stops these clots from forming, they said.

"There is no other drug that has these three different effects -- anti-viral, anti-inflammatory and anti-coagulant," said Page. The researchers said because the drug has antiviral properties and calms the immune system down it could be used at different stages of treatment. When inhaled, heparin also shows promise as a preventative and could be used to boost vaccination efforts, they said. Experts agree that vaccination alone is not going to stop the pandemic.

The new drug could assist in poorer countries where vaccination is challenging, and help front line workers who could use it as a preventative measure, the researchers said. "Inhaled heparin is a promising new possibility to provide a low-cost, safe and effective treatment for COVID-19 that is available and affordable to low and middle-income countries around the globe," Van Haren added.