The World Health Organization declared COVID-19 a global pandemic on March 11. As of press time, the coronavirus had rapidly spread to more than 175,000 people in 162 countries and caused nearly 7,000 deaths.

Doctors Michel Chrétien and Majambu Mbikay, senior researchers at the Montreal Clinical Research Institute (IRCM), have proposed the use of a plant-based compound called quercetin to treat COVID-19. Clinical trials to test its effectiveness are scheduled to start in China within the next few weeks.

Chrétien and Mbikay say that quercetin, which some research suggests can protect against the Ebola and Zika viruses, may be able to treat the coronavirus. Working with Chinese health officials, they will supervise clinical trials for testing the drug on patients in China. They will use the drug produced by the Swiss company Quercegen Pharmaceuticals, which, according to Chrétien, produces the purest available quercetin. The trials will last around four months.

Present in many fruits, vegetables, seeds, leaves, and grains, quercetin is a compound that originates from flavonoid plants. It is non-toxic for humans and can be purchased over the counter as a dietary supplement.

Chrétien and Mbikay’s interest in quercetin started in the 1990s, when they screened for mutations in gene PCSK9, a master regulator of cholesterol in circulation. They realized that children with less functional PCSK9 are less susceptible to malaria, which motivated them to look for a natural oral compound to inhibit PCSK9 functioning.

“We were looking for the compound […] that could be ingested and inhibit PCSK9 and cause a decrease [in] blood cholesterol,” Mbikay said. “What we observed is that [quercetin] was a very potent inhibitor of PCSK9. In other words, it could lower cholesterol.”

They then investigated quercetin’s inhibiting effects on parasites, bacteria, and viruses, especially after the outbreaks of the SARS-CoV and Ebola viruses in 2003 and 2018, respectively. These investigations unravelled the pivotal role of quercetin not only as an anti-metabolic compound through affecting PCSK9 and lowering cholesterol but also as a potential antiviral agent that targets the entry process of viruses.

During the last decade, research by Chrétien, Mbikay, and colleagues has suggested that quercetin can protect mice from Ebola and Zika viruses. After the recent COVID-19 outbreak, they proposed quercetin to Chinese health officials as a potential wide-spectrum antiviral drug.

“A cell has a lock, and the virus has a key [to enter and infect the cell],” Chrétien said “But quercetin puts glue in the lock.”

As of Feb. 15, China planned to run more than 80 clinical trials to treat COVID-19, testing a variety of potential remedies, such as HIV drugs, stem cells, and traditional Chinese medicines. Chrétien explained that quercetin has three advantages over other candidate treatments: It is taken orally; it is a natural, plant-based product; and it is relatively cheap.

“[Quercetin] costs peanuts compared to the antivirals that are on the market, which cost sometimes $1000 [per] shot,” Chrétien said. “Two months ago, you could have a one day treatment [of over-the-counter quercetin] for two dollars.”

On March 4, the Lazaridis Family Foundation contributed $1 million to support this project. Chrétien says that this suffices for the first one or two months of the project but estimates that they will need $5–6 million per year.

“We are asking our government to give us money to guide the Chinese,” Chrétien said. “I think our government will gain a lot […] not only on the health of people, but [in] their relationship with China.”

However, the world must wait four months to know whether quercetin cures or prevents COVID-19.

“The worst thing in medical science is to give false hope,” Chrétien said.