COVID-19 Relapses, Lack Of Omicron Data Complicate Paxlovid Case In India
Executive Summary
A few cases of COVID-19 relapse have Twitter abuzz about the need for data on Paxlovid’s effectiveness, particularly against the Omicron variant and in vaccinated individuals. Despite regulatory approval in India, the drug has not yet been included in treatment guidelines and a debate on recommended dosage now complicates matters.
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A collective sigh of relief was heard across the world when Paxlovid, Pfizer Inc.’s co-packaged nirmatrelvir and ritonavir treatment for COVID-19, was launched. However, Twitter has been abuzz of late with news of the disease relapsing in a few individuals despite having taken the recommended five-day course of the drug.
When Pfizer sought an Emergency Use Authorization (EUA) from the US Food and Drug Administration (FDA), it had submitted data from unvaccinated patients against the Delta variant. Later, it said that nirmatrelvir is a strong inhibitor of the Omicron 3CL protease and combined with existing data on Paxlovid’s efficacy against other variants of concern (VOCs), indications are that the antiviral will demonstrate robust activity against VOCs.
The Omicron variant and its sub-variants seem to be driving the recent surge of COVID-19 across the world even as large parts of the population, particularly in countries like US, UK, India and China have been partially/fully vaccinated or have had contracted the disease at least once.
After media reports of COVID-19 rebounding in some of those who took Paxlovid, Pfizer CEO Albert Bourla suggested on Bloomberg that patients could take another course. (Also see "Coronavirus Update: FDA Tries To Control J&J’s Vaccine, Extended Use Of Paxlovid" - Scrip, 6 May, 2022.)
FDA’s director of the Office of Infectious Diseases, John Farley countered saying there is no “evidence of benefit at this time for a longer course of treatment … or repeating a treatment course of Paxlovid in patients with recurrent COVID-19 symptoms following completion of a treatment course.”
A Question Of Data
Twitterati offered explanation on what could possibly be happening. Michael Mina, epidemiologist and pathologist, said “even though Paxlovid works just as well to limit Omicron as it does Delta on a “drug to virus basis” in a petri dish, I believe Paxlovid in the trials was also benefitting from any lingering Delta virus being eliminated better by immunity when some virus remained after.”
“Although a 5-day course was successful at eliminating the virus in the trials - that was with Delta! It is likely that a 5-day course may not be sufficient for Omicron because the same level of immune system participation doesn't occur as effectively to clear Omicron (vs Delta),” the former faculty member at Harvard added in one of series of tweets on the issue.
However, there seems to be a case for Pfizer itself to study the efficacy/effectiveness of Paxlovid in vaccinated individuals and against Omicron, formally revising its recommended dosage if required. (Also see "Pfizer On Paxlovid: "There's Still A Long Way To Go"" - Scrip, 3 May, 2022.)
Not Included In India’s Guidelines
Meanwhile, experts from the leading research and advisory body Indian Council of Medical Research (ICMR) have not yet found reason to include Paxlovid in the national treatment guidelines for COVID-19.
The drug has regulatory approval from the Drugs Controller General of India (DCGI), but ICMR’s head of epidemiology and infectious diseases, Samiran Panda told local media that members of its national task force on COVID-19 were not convinced of the need to add the drug to the recommended list of treatments for the disease.
"As of now the current evidence doesn't support its inclusion. But there are trials which are undergoing and we are waiting for more data and will review it again," Panda was quoted as saying.
Incidentally, ICMR had not included Merck & Co., Inc./Ridgeback Biotherapeutics LP ’s Lagevrio (molnupiravir) in the national treatment guidelines as well. (Also see "ICER Gives Cold Shoulder To Merck/Ridgeback’s COVID-19 Pill" - Scrip, 10 May, 2022.)
The current scenario has left physicians confused over whether or not to prescribe Paxlovid to patients who are eligible to receive the treatment. “We are willing to prescribe since it has shown that it prevents hospitalization in the vulnerable and the possibility of preventing long COVID is a good enough reason, but the guidelines should be clear,” said one.
Hetero Could Have First Indian Generic
Guidelines aside, the drug needs to be available in India first. In March, the Medicines Patent Pool signed sub-licensing agreements with 35 companies for manufacture of Paxlovid’s generic versions for distribution in 95 low- and middle-income countries.
Among these were Beximco Pharmaceuticals Ltd., which had already launched the first generic version in Bangladesh, Teva Pharmaceutical Industries Ltd., Hikma Pharmaceuticals plc, Fosun Pharmaceutical and Celltrion. Indian companies included Sun Pharmaceutical Industries Ltd., C#4623:Cipla Limited], Torrent Pharmaceuticals Ltd., Aurobindo Pharma Limited, Glenmark Pharmaceuticals Limited and Biocon, Ltd., as well as others.
It’s likely that Hetero Laboratories will steal a march over the other Indian companies in manufacturing and marketing the drug in the country. A company spokesperson, however told Scrip that “there’s no update” regarding a launch date.
Pricing In Focus
While Pfizer itself has admitted to facing some obstacles in rolling out its product, patient activist groups and some agencies had said in March that it would take several months for generics to reach nations in need and even at that point, pricing could impede access.
Beximco had launched the generic at around $186 for the five-day course. A recent Reuters report has cited the Clinton Health Access Initiative (CHAI) to say that Paxlovid could be made available to low- and middle-income countries by other generic manufacturers at $25 a course or even less. (Also see "Beximco Delivers First Cut-Price Generic Paxlovid" - Scrip, 31 Dec, 2021.)
CHAI did not disclose the manufacturers' names as they are still in the early stages of product development and have not received regulatory approval, it added.
If Pfizer does revise the recommended dosage of Paxlovid upward, pricing will become even more relevant for access.
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