Antiviral drugs against Covid-19 could be a game-changer in the pandemic as they could potentially reduce transmission in patients.
Experts said vaccines, however, remained the ultimate shield against the SARS-CoV-2 virus that causes Covid-19, as they provided long-term and robust protection.
Molecular virologist Dr Vinod Balasubramaniam of the Jeffrey Cheah School of Medicine and Health Sciences at Monash University Malaysia, said vaccination and booster shots for selected individuals should remain a long-term priority for governments worldwide.
"Vaccines offer protection via immunological memory against Covid-19 before the real infection itself, training our body to be ever ready to fight this disease. This is something an antiviral pill cannot provide.
"Antiviral strategies, such as using Molnupiravir should be added to the country's portfolio to give a 'synergistic' effect, which will have a better outcome in managing Covid-19 and future pandemics," he told the New Straits Times.
Molnupiravir — meant for people who are sick with Covid-19, but are not in the hospital — is the new oral antiviral medicine for Covid-19 developed by American pharmaceutical company Merck & Co.
Merck said interim clinical trial results suggested that the experimental drug cut the risk of hospitalisation or death by about half.
It said late-stage clinical trials showed that 7.3 per cent of patients who received the drug were hospitalised, and none died, while 14.1 per cent of the patients who got a placebo were hospitalised or had died.
Merck did not note any side effects from Molnupiravir and said the rate of complications was similar between the placebo group and the treatment group.
Health Minister Khairy Jamaluddin on Saturday said Malaysia had started negotiations to procure Molnupiravir.
Dr Vinod said while there were several treatments for Covid-19 on the market, many of them were expensive, difficult to administer, not widely available, or only marginally effective.
He said drugs that had little evidence behind them, like the antiparasitic Ivermectin and the anti-malarial Hydroxychloroquine, had gained traction in some circles.
Molnupiravir, originally developed to treat influenza, could solve many of these challenges, he said.
"It's administered as a twice-a-day pill for five days, compared with other Covid-19 treatments that require expensive intravenous transfusions, such as monoclonal antibodies and convalescent plasma.
"The antiviral drug Remdesivir, currently the only drug with full Food and Drug Administration (FDA) approval to treat Covid-19, also has to be delivered into the bloodstream."
Molnupiravir, he said, worked a lot like Remdesivir, but the former offered the possibility of a stronger, more targeted approach.
"The SARS-CoV-2 virus makes copies of itself by encoding instructions on RNA, which is made up of base molecules identified by the letters A, C, U, and G. While Remdesivir imitates A (adenosine), Molnupiravir can mimic U (uracil) or C (cytosine).
"When the virus incorporates Remdesivir into its RNA, the drug causes its reproductive cycle to stall. Molnupiravir works a little differently, causing genetic mutations that hamper the virus.
"Crucially, these drugs can fool the virus, but they don't fool human cells, so they have a targeted effect and for the most part, leave the human cells alone."
As the unvaccinated continue to make up most hospitalisations and deaths globally, treatments for Covid-19 remained a vital component of the pandemic response, said Dr Vinod.
A drug like Molnupiravir, he said, could be useful as it was administered in the early stages of the disease.
"Since it's just a pill, it may spare the patient a trip to a clinic for a transfusion for treatments, like monoclonal antibodies. That reduces the chances of an infected patient transmitting the virus to medical staff, and it averts potential complications associated with transfusions.
"Besides, if this new pill holds up to scientific scrutiny, it will be big news. Effective pills given to outpatients could make a large difference for several distinct groups.
"It could prevent progression to more severe, even life-threatening illness, provide an alternative approach to prevent severe disease in people who are against vaccinations and vaccine-non-responders (those with severely weakened immune systems), and potentially protect those with recent close exposure to an active case.
"But more information is needed, such as its use on teens and younger children, a population that could benefit greatly, given the lack of authorised vaccines for 11-year-olds and younger kids."
Epidemiologist Professor Datuk Dr Awang Bulgiba Awang Mahmud of Universiti Malaya said Molnupiravir was supposed to suppress replication of SARS-CoV-2, hence, hopefully, it would be effective against variants that had mutations in the spike protein.
"That would be its advantage over monoclonal antibodies but again whether the virus mutates to try to evade the drug remains to be seen. As this is a drug and not a vaccine, it would not require a cold chain and could be administered to patients who require it."
He said the drug, however, did not eliminate the need for vaccines as vaccines worked by stimulating the body to mount its own defence against Covid-19.
Merck expects to be able to make enough pills for 10 million people by the end of this year.
Other companies developing antiviral drugs include Pfizer, Atea Pharmaceuticals and Roche.