All you need to know about Paxlovid, the most promising COVID-19 drug

Both companies are likely to restrict sales to hospitals and for government purchases, at least in the initial stage to prevent misuse by private pharmacies and online channels.

Why Paxlovid for COVID-19?

It is a combination of Nirmatrelvir, an antiviral medicine, which stops the virus from spreading into the body, and Ritonavir, which works like a booster that increases the availability of Nirmatrelvir in the body to maximise the effectiveness of this combination medicine.

The drug, approved by the US Food and Drug Administration for COVID-19, had shown 89 percent efficacy in phase 2 and 3 clinical trials when given within three days of symptoms, and a US study has showed that it reduced hospitalisation or death by 49 percent in a highly vaccinated group of people of over 50 years of age.

“This would be a real-life future situation,” pointed out senior virologist Dr Shahid Jameel, who is associated with the Green Templeton College at the University of Oxford.

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Importantly, the drug’s clinical trial has shown that it works well in vaccinated people, too, as 90.3 percent of people in the US study had three or more vaccine doses. It may be crucial for a small fraction of those who get infected and may develop serious complications, despite a very high COVID-19 vaccination coverage in India.

The FDA has authorised the emergency use of Paxlovid for the treatment of mild-to-moderate COVID-19 in adults and children (12 years of age and older, weighing at least 40 kg), with a positive test for SARS CoV 2, who are at high risk for progression to disease including hospitalisation or death.

Also, the drug is only indicated within five days of the onset of symptoms.

The drug has received much attention globally over the last several months as it showed efficacy and promise against all variants of SARS CoV 2, including Omicron, and its various sub-variants which have shown immune escape properties and are capable of causing repeat infections.

“A treatment that works across all variants, Paxlovid is going to be useful for patients who have risk factors for severe disease,” said virologist Dr Gagandeep Kang, who teaches at the Christian Medical College, Vellore.

The frequency of infection may have reduced markedly at the moment, but that does not mean that cases will not rise in the unpredictable future, said Kang.

As the virus has evolved to escape immunity, the monoclonal antibody therapies no longer work, Kang said. So, Paxlovid is the only specific antiviral we have, since Molnupiravir (another drug indicated for COVID-19) seems to be not very good and has safety concerns.

Availability in India

The Medicines Patent Pool (MPP), a United Nations-backed body, announced in March 2022 that it had signed agreements with 35 companies to manufacture the generic versions of Paxlovid that can be supplied in 95 low- and middle-income countries.

They include 19 drug makers from India. Sun Pharma, Cipla, Glenmark, Emcure, Aurobindo Pharma, Hetero and Zenara figure in the list.

The companies that were offered the sublicence demonstrated their ability to meet the MPP’s requirements related to production capacity, regulatory compliance as well as international standards for quality-assured medicines.

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However, it was the requirement related to local clinical trials and pricing negotiations that delayed the launch of the drug in India, industry sources told Moneycontrol.

But now that patients in India can hope to access the drug, experts explain why it will do good for the country to have the drug in its armament as the disease has reached an endemic stage.

“When a virus becomes endemic, good drugs to manage disease in vulnerable populations, in this case, the elderly and those with comorbidities, becomes very important,” said Jameel. “Therefore, the introduction of generic Paxlovid is a very welcome step,” he said.

Some concerns

While there is some hope that Paxlovid may also be useful for long COVID, or people living with some symptoms of COVID-19 for weeks, months or even years after recovering from the initial infection, there is no concrete data to back the claim.

“It’s too early to say if it protects against long COVID-19,” said Jameel, adding that if the drug clears infection quickly, one can expect it to also reduce long COVID.

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Dr Raymond Savio, who, as a critical care clinician, has been seeing patients struggling with severe COVID-19 since the beginning of the pandemic, suspects that there may be a surge of unwarranted prescriptions once the drug is available.

The public should at least be made aware that this is not for asymptomatic disease and should not be taken by pregnant women, and people with severe renal and liver disorders, he cautioned.  “The bottom line is the same message; each drug has its specific indication and requires judicious prescription”.