Paxlovid vs Monoclonal Antibodies: Effective against Omicron?

Most people with COVID-19 will experience a mild illness, and they’ll be able to take care of themselves at home. But some—especially those with underlying health conditions—could benefit from one of several COVID-19 treatments. Some of these are available in pill form and others are given intravenously or by injection—and all of them must be prescribed by a health care provider.

In this article, we will do a roundup and cover 2 popular anti-viral treatments i.e. Paxlovid and Monoclonal Antibodies.

Paxlovid

Paxlovid is Pfizer’s brand name for an antiviral oral medication (in pill form) that combines two generic drugs, nirmatrelvir and ritonavir. It was the first COVID-19 antiviral pill to receive Food and Drug Administration (FDA) emergency use authorization (EUA) in December 2021, and the National Institutes of Health (NIH) has prioritized its use over other treatments for eligible patients. It is meant for people who have a current COVID-19 infection.

How to Get Paxlovid Without a Medical Doctor

In March 2022, the Biden administration launched the Test to Treat initiative. The initiative’s goal was to allow people to be tested for COVID-19 at pharmacies or health centers that have an on-site clinic, like CVS MinuteClinic. If you had a positive test, you’d then receive an antiviral prescription at the pharmacy before leaving the building.

While well-intentioned, there were many roadblocks that made the Test to Treat initiative difficult to roll out. One big barrier was the fact that most pharmacies don’t have clinics in the same building. In late May 2022, there were only about 2,500 Test to Treat locations in the entire U.S. This left many Americans still struggling to get a prescription from their healthcare providers in enough time to benefit from Paxlovid.

In response to this, the FDA updated Paxlovid’s EUA in July 2022. This change allows pharmacists to prescribe Paxlovid directly to people who have tested positive for COVID-19. This means that you might be able to head over to your local pharmacy for the medication without having to make other stops along the way. Keep in mind that not all pharmacies may offer this service.

To get Paxlovid from your pharmacist, you must bring the following documents with you to the pharmacy:
  • Your current health records, which must be less than a year old (either electronic or printed records are fine)
  • Your most recent liver and kidney function tests, which must be less than a year old
  • A complete list of all medications that you take, including any over-the-counter (OTC) medications, vitamins, and supplements
If you don’t have all of this information available, or your records aren’t recent enough, there may be a delay in getting Paxlovid. A pharmacist can reach out to your provider by phone to get this information, but that takes time. In this case, pharmacist-prescribed Paxlovid might not be much faster than seeing your healthcare provider or visiting a Test to Treat location.

How much will Paxlovid cost? 

The U.S. will pay about $500 for each course of Pfizer’s treatment, which consists of three pills taken twice a day for five days. Two of the pills are Paxlovid and the third is a different antiviral that helps boost levels of the main drug in the body.

New Paxlovid Dose Pack Author​ized by FDA

On April 14, 2022, the U.S. Food and Drug Administration (FDA) revised the Emergency Use Authorization (EUA) for the COVID-19 oral antiviral therapeutic Paxlovid to authorize an additional dose pack presentation with appropriate dosing for patients with moderate renal impairment within the scope of the EUA. As a result, Paxlovid will soon be available in two package presentations:
  1. ​The standard packaging that is currently in distribution: 300 mg nirmatrelvir;100 mg ritonavir - Each carton contains 30 tablets divided in 5 daily-dose blister cards. Each blister card contains 4 nirmatrelvir tablets (150 mg each) and 2 ritonavir tablets (100 mg each). Nirmatrelvir tablets and ritonavir tablets are supplied in separate blister cavities within the same child-resistant blister card.
  2. The new packaging option that will be in distribution later this month: 150 mg nirmatrelvir; 100 mg ritonavir - Each carton contains 20 tablets divided in 5 daily-dose blister cards. Each blister card contains 2 nirmatrelvir tablets (150 mg each) and 2 ritonavir tablets (100 mg each). Nirmatrelvir tablets and ritonavir tablets are supplied in separate blister cavities within the same child-resistant blister card.
The updated provider Fact SheetLetter of Authorization, and Dear Healthcare Provider Letter​ are available for reference.

Precaution: PAXLOVID is not recommended (the appropriate dose has not been determined) in patients with severe renal impairment (<30 mL/min). (Source)

Paxlovid Doesn’t Work for Healthier Patients, Pfizer Says (Time.com - June 2022)

Pfizer Inc. plans to stop enrollment in a study of its COVID-19 drug in patients who aren’t at high risk of severe disease after the pill didn’t help alleviate their symptoms, a major setback for broader use of the treatment.

The New York-based drugmaker said Tuesday that it would stop adding new participants to a highly anticipated study testing Paxlovid in a broader population of COVID patients who are at low risk of hospitalization and death. The decision comes after the study failed to demonstrate that the drug reduced COVID symptoms among relatively healthy patients and wasn’t able to show a statistically significant reduction in hospitalization and death.

Paxlovid Rebound

In late May 2022, the CDC issued a health advisory about “COVID-19 rebound” after Paxlovid treatment. The CDC described it as “a recurrence of COVID-19 symptoms or a new positive viral test after having tested negative.”

At the same time, the CDC wrote, “a brief return of symptoms may be part of the natural history of [coronavirus] infection in some persons, independent of treatment with Paxlovid and regardless of vaccination status.”

The CDC said there is no evidence for more treatment in rebound cases, though people should isolate again for at least 5 days so they won’t pass COVID-19 to others.

People who have a rebound after taking Paxlovid can report their cases to Pfizer’s adverse event reporting page.

Paxlovid's Contraindications and Drug Interactions

Pfizer anti-COVID pill's interaction with common drugs will narrow its benefit, experts say | National Post:

The buzz around PAXLOVID™ has largely obscured one major downside of this treatment. Ritonavir can interact dangerously with a slew of commonly used medications, pumping up the potency of blood thinners, heart-arrhythmia therapies, epilepsy drugs and others. And the patients targeted for its use – those most at risk of serious COVID disease because of age and other health issues – are also the people most likely to be taking those “contraindicated” medications. 

In some cases, the interactions could be managed, but it’s clear the problem will limit the pool of potential recipients, experts say. “It has a utility, it has a use,” said Dr. Gerald Evans, head of the Infectious Diseases Division of the Queen’s University medical school. “(But) I certainly would not call it a game-changer.” “A patient on blood thinners could end up with spontaneous bleeding in the gastrointestinal tract or brain”, noted Evans. 

“Someone taking pills for hypertension might see their blood pressure fall so much they pass out”, said Dr. Andrew Hill, a pharmacology researcher at the U.K.’s Liverpool University. “There are all kinds of ways that PAXLOVID™ could cause serious harm,” he said. 

Ritonavir is also used in HIV treatments, so there is a wealth of knowledge about those potential drug interactions. The U.S. Food and Drug Administration (FDA) product monograph for PAXLOVID™ lists over 100 drugs that it says should not be taken with the COVID pills, or whose use ought to be carefully monitored. The figure below lists a few of these drugs as well as liver enzymes whose functions are impacted by Ritonavir.

See Sections 4 and 7 of the FACT SHEET FOR HEALTHCARE PROVIDERS and a publication on JAMA by Ross et al. Pharmacists as prescribers may be a problem since they are not authorized to manage, deprescribe and be responsible for the OTHER drugs.


Bebtelovimab (Monoclonal Antibody)

Bebtelovimab is an US FDA-authorized investigational monoclonal antibody treatment that was developed by Eli Lilly. 

Is bebtelovimab effective against omicron: Data showing bebtelovimab’s efficacy against Omicron and its BA.2 subvariant prompted the FDA to authorize the drug through an EUA. A lab study published in July 2022 (NEJM) using the live-virus Focus Reduction Neutralization Testing (FRNT) method revealed that bebtelovimab seems to be the most promising monoclonal antibody against the Omicron BA 5 subvariant.

monoclonal antibodies
Credit: Design Cells/SPL

When it was authorized: February 2022.

Who can get it: Adults and children ages 12 and up who weigh at least 88 pounds. They must have a positive COVID-19 test result and be at high risk for developing severe COVID-19.

How you take it: An intravenous injection is given for at least 30 seconds. Patients are observed by a health care provider for at least an hour after injection. Bebtelovimab must be given within seven days of symptom onset.

Side effects: There is limited information known about the safety and effectiveness of bebtelovimab for the treatment of mild-to-moderate COVID-19, according to the FDA fact sheet. The sheet also provides a list of potential side effects the FDA recommends reporting to a medical provider, and reports that allergic reactions can happen during and after injection. Because bebtelovimab is still being studied, it’s possible that all of the risks aren’t yet known.

How it works: It binds to the spike protein that causes COVID-19, similar to other monoclonal antibodies that have shown efficacy against hospitalization and death from the disease.

How well it works: The EUA for bebtelovimab was supported by clinical and nonclinical data that showed it has efficacy against Omicron and its BA.2 subvariant. The clinical data was based on a Phase 2 trial that treated non-hospitalized patients with bebtelovimab alone or together with another drug called etesevimab. That study is available in a preprint, which has not yet been peer-reviewed.

What else you should know: There is limited experience treating pregnant women or breastfeeding mothers. So, those patients should discuss their options and specific situation with their health care provider.

The NIH considers this to be an alternative treatment, which should be used only when neither of the NIH-preferred therapies (Paxlovid and remdesivir) are available, feasible to use, or clinically appropriate.

More information: FDA bebtelovimab fact sheet for patients, parents, and caregivers.


The COVID-19 Treatment Guidelines Panel’s Statement on Therapies for High-Risk, Non-hospitalized Patients With Mild to Moderate COVID-19 (Last Updated: August 8, 2022)

This statement contains the Panel’s recommendations for treating these non-hospitalized patients using the currently available therapies.

For Patients Who Are at High Risk of Progressing to Severe COVID-19
Preferred therapies. Listed in order of preference:
  • Ritonavir-boosted nirmatrelvir (Paxlovid)
  • Remdesivir
Alternative therapies. For use ONLY when neither of the preferred therapies are available, feasible to use, or clinically appropriate. Listed in alphabetical order:
  • Bebtelovimab
  • Molnupiravir

Effectiveness of Monoclonal Antibodies and Antiviral Drugs against Omicron BA.2.12.1, BA.4, and BA.5 Subvariants | NEJM

A lab study published in July 2022 (NEJM) using the live-virus Focus Reduction Neutralization Testing (FRNT) method revealed that bebtelovimab seems to be the most promising monoclonal antibody against the BA 5 subvariant.


Overall, the study data also revealed that the three antiviral drugs remdesivir, molnupiravir, and nirmatrelvir (Paxlovid) may still have therapeutic value against the sublineages BA.2.12.1, BA.4, and BA.5 of SARS-CoV-2 omicron variants.


Do take note of the limitation of this study as this is a non-clinical study (not in humans). There is lack of clinical data on the efficacy of these monoclonal antibodies and antiviral drugs for the treatment of patients infected with BA.4 or BA.5 subvariants. Therefore, the selection of monoclonal antibodies or anti-virals to treat patients who are infected should be carefully considered based on the potential risks as compared to its potential benefits.

Key Takeaways

You should never attempt to self medicate without the guidance of a licensed medical provider. If you are not a medical doctor, you are likely to find the above information overwhelming and complicated. The aim of this article is to empower you with a better understanding of the options available and to discuss the options with your medical doctor.

If you are experiencing symptoms of COVID-19 and think you are eligible for a treatment, you can visit the government Test-to-Treat Locator. You can use the site to search for places near you where you can fill a COVID-19 prescription or identify sites that provide testing, medical care, and COVID-19 medications.


Updates: 




Disclaimers:

Information provided in this article is for general informational purposes only. No content in the articles should ever be used as a substitute for medical advice from your doctor or other qualified clinician. Always seek the individual advice of your trusted health care provider with any questions you have regarding a medical condition.  

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