[Reading Science] The Bitter Reality of the 'Game Changer' Paxlovid

Low Adoption Due to Rebound Effect and High Prices
International Journal Nature Points Out

[Image source=Yonhap News]

[Asia Economy Reporter Kim Bong-su] Paxlovid, a treatment that debuted spectacularly at the end of 2021 amid the COVID-19 pandemic with high expectations as a "game changer," is reportedly failing to fulfill its role due to its high price and concerns over side effects, according to the international academic journal Nature on the 3rd (local time).

Paxlovid, developed by multinational pharmaceutical company Pfizer, received its first approval in the United States in December 2021, attracting significant spotlight. Paxlovid is an oral medication synthesized by combining the antiviral agent nirmatrelvir and the booster ritonavir. Clinical trials showed that when taken within three days of symptom onset by vulnerable groups such as the elderly and those with underlying conditions, it reduced mortality and hospitalization rates by up to 89%, generating great global expectations.

However, the drug is currently underutilized. In the United States, health authorities purchased enough Paxlovid for 10 million people, but only 6.7 million courses have been used. According to a recent survey conducted by UK-based health statistics company Airfinity targeting physicians, the prescription rate of Paxlovid for new COVID-19 patients was only 0.5% in the UK and about 13% in the US.

The low prescription rate of Paxlovid is attributed not only to its high price and supply shortages but also to the so-called rebound phenomenon, where patients test positive again after recovery, causing hesitation in taking the medication. Representative cases include the reinfections of Rochelle Walensky, director of the US Centers for Disease Control and Prevention (CDC), and President Joe Biden and his wife in October last year.

However, experts emphasize that Paxlovid effectively prevents the replication and spread of the COVID-19 virus in the early stages of infection, thereby preventing severe illness, and that it is effective against the Omicron variant. They also point out that the "rebound phenomenon" occurs in all COVID-19 patients and is therefore unrelated to any defects or side effects of Paxlovid.

David Smith, a professor of infectious diseases at the University of California, told Nature, "Paxlovid remains the only treatment capable of preventing death in high-risk groups after it was confirmed that monoclonal antibody therapies are ineffective." He added, "It was a game changer with good efficacy even against Omicron, but it is unfortunate that the rebound phenomenon has become a stigma causing people to avoid taking it." Side effects have also been reported, such as the inability to combine it with other drugs and some people experiencing a bitter or metallic taste after taking it, which raises concerns about toxicity.

Infrastructure shortages are also an obstacle. Since Paxlovid must be taken early in the infection to be effective, the presence of medical infrastructure for testing, prescribing, and dispensing in the respective country is a key factor in expanding its distribution. In underdeveloped countries lacking such infrastructure and among certain groups in developed countries, proper distribution has not been achieved. In fact, a survey of 700,000 COVID-19 patients across 30 regions in the US found that marginalized groups such as Black and Hispanic populations had Paxlovid prescription rates approximately 36% and 30% lower, respectively, compared to well-off groups like Whites.

The emergence of other treatments is also threatening Paxlovid's position. In November last year, Japanese health authorities approved Ensitrelvir, a once-daily oral antiviral antibody treatment jointly developed by Shionogi Pharmaceutical and Hokkaido University. China also approved a COVID-19 antiviral drug in July last year.