The chief executive of Novartis cautioned on Friday that it is "too soon" to be sure whether two anti-malaria drugs could be a definitive treatment for the coronavirus.
President Donald Trump touted them as a "game-changer" for the global outbreak.
As of Friday, more than 537,000 people around the world had contracted COVID-19, according to data compiled by Johns Hopkins University, with 24,110 deaths.
There are no vaccines or treatments available for the virus, but trials are underway to find drugs that could serve this purpose.
One of those trials, led by the University of Minnesota, will test to see whether hydroxychloroquine can prevent or reduce the severity of the coronavirus. Novartis is one of the main producers of this anti-malaria drug.
"With hydroxychloroquine, what we know is in preclinical studies, the drug is quite active against the coronavirus but these are, of course, not in human beings — not in patients," Novartis CEO Vas Narasimhan told CNBC's "Squawk Box Europe" via video link on Friday.
"I do think it is too soon to know for sure until we have properly controlled randomized studies," he said. "We hope over the next 18 months to two years, we can come back with a vaccine that will ultimately be the definitive way to deal with this pandemic."
Chloroquine is a decades-old drug that was approved by the Food and Drug Administration in 1949 to treat malaria. Its derivative, hydroxychloroquine, is often used by doctors to treat rheumatoid arthritis and lupus.
Speaking at a White House press briefing last week, Trump said that the two anti-malaria drugs were a "game-changer" in the global fight against the coronavirus pandemic, adding that they had shown "very, very encouraging results.″
At present, none of the drugs being discussed has been put through the rigorous clinical trials needed in order to receive approval to fight the coronavirus.
Since emerging from Wuhan, China, in late 2019, the coronavirus has spread to more than 190 countries, areas or territories.
The outbreak has been recognized as a pandemic by the World Health Organization, with the United Nations health agency repeatedly underlining the importance of nations moving to impose sweeping public health measures.
When asked whether the coronavirus pandemic had been made even worse by a failure of global policy, Narasimhan replied: "Our struggle globally to respond to pandemics goes back now decades and the challenge fundamentally is because of a lack of preparedness in the world of biodefense — as we have, I believe, in the broader defense complex."
"You need to maintain a baseline level of preparedness across the global system. What we see time and again, if you back to SARS, if you go back to swine flu — the H1N1, 2009 — there is a surge of effort right after a pandemic and then the effort starts to fade away."
"I think a lot of that has to do of us viewing this as a health issue rather than as a health and defence, and broader societal topic, that would lead, I think, to much stronger preparedness in the system," he added.
— CNBC's Berkeley Lovelace Jr. contributed to this report.
Clarification: This report was revised to refer to hydroxychloroquine as a possible treatment for COVID-19.