Antiviral Research: COVID-19 Oral Antiviral Clinical Study Results

The efficacy of antiviral medicines like Paxlovid and Lagevrio in antiviral research is becoming clearer, especially for at-risk older individuals. Discover the latest insights into these oral antivirals, available in Australia and prescribed by general practitioners under the Pharmaceutical Benefits Scheme (PBS). Stay informed on advancements in antiviral research.

Despite the fact that both medicines have gained provisional approval from the Therapeutic Goods Administration (TGA) based on clinical research, there is still a lack of understanding about how they operate in real-world scenarios, especially in light of the development of
Omicron.

The two latest studies aimed to close that knowledge gap.

According to one Hong Kong research, both are effective in avoiding or treating severe disease, with nirmatrelvir/ritonavir providing the highest degree of protection.

Another recent Israeli study focused only on the outcomes of patients who got nirmatrelvir/ritonavir medication. An oral antiviral had “no significant impact” on a younger group of patients aged 40 to 64, but is most useful in vulnerable seniors 65 and older, according to one research.

Hong Kong’s inquiry

The University of Hong Kong researchers claim that their study is the first to look at the therapeutic use of oral antivirals in the real world when Omicron is the prevalent strain.

An observational, retrospective cohort study including 40,776 hospitalized patients in Hong Kong was conducted from February 26 to April 26 of this year.

1000 patients were given nirmatrelvir/ritonavir, whereas 2359 were given molnupiravir.
None of the patients required oxygen therapy at the outset of their treatment. The study’s findings were evaluated using disease progression, mortality, whether patients required a ventilator, and the pace at which the viral load reduced.

The findings for oral antiviral users were compared to controls using propensity score matching.
The study discovered that taking oral antivirals was linked with a significantly lower risk of disease progression, with hazard ratios of 0.53 and 0.33 for molnupiravir and nirmatrelvir/ritonavir, respectively.

Similarly, hazard ratios of 0.32 for nirmatrelvir/ritonavir and 0.55 for molnupiravir were found for all-cause mortality.

The study also compared the two drugs, with the molnupiravir group having a higher relative risk of death than the nirmatrelvir/ritonavir group.

Molnupiravir was connected to a higher chance of longer hospital stays among those who survived.

The researchers discovered that “early initiation of oral antivirals within two days of admission was associated with significantly lower risks of disease progression and all-cause mortality, as well as achieving low viral load faster than their respective matched controls.”

Those who took molnupiravir had a far reduced chance of requiring invasive mechanical breathing than those who did not.

Despite the fact that both therapies reduced severe outcomes, the authors explicitly declared their preference.

Given the former’s considerable mortality benefit, the researchers concluded that their findings “also support the prioritisation of nirmatrelvir/ritonavir use over molnupiravir use in COVID-19 patients whenever accessible and clinically appropriate.”

The second study

Following that, researchers from Israel’s Clalit Health Services (CHS) and Ben-Gurion University of the Negev released a separate pre-print study this week that focused only on nirmatrelvir/ritonavir.

It employed medical record data from CHS, which the authors describe as “a large healthcare organization covering approximately 52% of the entire Israeli population and nearly two-thirds of the older adults,” similar to the Hong Kong study. The authors characterize CHS as “a large healthcare organization covering approximately 52% of the entire Israeli population.”

The experiment lasted two months, from 9 January to 10 March of this year, and included all CHS members with confirmed COVID-19 who were thought to be at high risk of developing severe disease. Once again, Omicron was the dominant strain in the country.

The study comprised all CHS participants who were 40 years of age or older and had SARS-CoV-2 infection confirmed.

Nirmatrelvir + ritonavir was given to 2504 of the 42,819 eligible patients above the age of 65, as well as 1435 of the 66,394 eligible patients between the ages of 40 and 64.

The study revealed that among treated people aged 65 and above, hospitalizations and death rates were much lower.

The authors discovered that nirmatrelvir treatment was associated with a 67% reduction in COVID-19 hospitalizations and an 81% reduction in COVID-19 death in those 65 and older.
In younger people, however, “no significant benefit in avoiding severe COVID-19 outcomes was shown.”

According to the researchers, immunosuppression was “significantly associated” with hospitalizations among patients aged 40 to 64. They also discovered that a lack of prior COVID-19 immunity and prior hospitalization were the characteristics most linked to high rates of hospitalization.Despite the trial’s observational nature, the authors stated, “We believe that the results and demonstrated potential for preventing severe COVID-19 should help decision makers prioritize the currently limited supply to individuals in whom nirmatrelvir has been shown to be significantly effective.”

The researchers emphasized the dependability of the data they used, but they also warned that ‘confounding clinical and sociodemographic factors’ might lead to biased conclusions.

The evidence is still being gathered.

Clinical studies for both of the medicines being used in Australia were done under radically different settings from those in use now.

Both drugs were tried on unvaccinated people during the Delta wave, before the Omicron variant was discovered.

In reality, when Omicron is the prevalent strain, oral antiviral drugs are often administered to a highly immunized population.

In March, senior scientists and physicians emphasized the critical need for further understanding of the mechanisms of action of the new oral antivirals.

Although the real-world efficacy of oral antiviral drugs has yet to be shown, TGA Head Professor John Skerritt has acknowledged the scarcity of data and anticipated that solid research would be released this year.

To relieve hospital overcrowding, at-risk persons with mild-to-moderate symptoms are currently the target of oral antiviral drugs.

It is suggested by prescribers that therapies begin within five days of the onset of symptoms in order to have the most benefit.

Although these exploratory studies suggest that nirmatrelvir + ritonavir is more effective than molnupiravir, it has much greater side effects.

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