Reports of Paxlovid “COVID-19 Rebound” doing the rounds

What is Paxlovid? 

Paxlovid is Pfizer’s antiviral treatment for COVID-19. It’s one of the new oral antivirals formulated to limit the impact of COVID-19 available on the Pharmaceutical Benefit Scheme (PBS).

It’s made up of two protease inhibitors, including one used in treating HIV as a booster medicine. Protease inhibitors are synthetic drugs that block enzymes that viruses need to replicate. The combination in Paxlovid basically prevents the coronavirus from completing its life cycle.

Paxlovid has been found to be effective in treating mild to moderate COVID-19 in eligible adults aged 18 years of age and older, who do not require supplemental oxygen, and who are at increased risk of progression to hospitalisation.

Who is eligible?

According to PBS criteria, the drug can be prescribed for those with mild-to-moderate COVID-19 confirmed by a PCR or rapid antigen test within five days of symptom onset, among the following patient groups:

  • Those aged 65 or older, with two other risk factors for severe disease
  • Those aged 75 or older with one other risk factor
  • Those aged 50 and older who are of Aboriginal or Torres Strait Islander origin with two further risk factors for severe disease
  • Those with moderate-to-severe immunocompromise

Paxlovid “rebound”

In recent weeks, there have been reports of ‘COVID-19 rebounds’ following treatment have been circulated. Some cases have been highlighted in the US, where the treatment has been approved since the end of last year. 

One such report describes a 71-year-old man whose COVID-19 symptoms reduced after two days of taking the drug. But, four days after finishing the full course of Paxlovid, they returned for a few more days. 

As per this article by CBC News, “The Centers for Disease Control and Prevention has been consulting with the National Institutes of Health (NIH) over potential data sources that can be used to study the cases, a CDC spokesperson” said in a statement. 

No NIH studies are underway yet, the NIH said in a statement, though federal scientists are “actively discussing” ways to investigate the phenomenon.” 

Are there any implications for prescribers in Australia?

As reported by RACPG’s conversation with infectious diseases physician and microbiologist Associate Professor Paul Griffin, “The reports are a part of an evolving understanding of the treatment – but should not affect the current clinical approach.”

“What this doesn’t change is the fact that the drug has certainly been proven in those unvaccinated high-risk people to reduce their chance of progressing to severe disease. These reports certainly don’t undermine its capability in that regard at all.”

In fact, the ‘rebound’ has only been observed in a small number of cases (between 1–2%) during the first clinical trials. The same trials also found that the treatment reduced the risk of hospitalisation and death among at-risk groups by 89%. Both Pfizer and the US Food and Drug Administration (FDA), have pointed out that the recurrence of positive tests was observed to a similar degree in the placebo group of the first clinical trials. They also both suggested no conclusions could be drawn about whether the treatment caused the rebound.

Opinions or facts expressed within the content have been sourced from various news sources. While every effort has been taken to source them accurately, the pharmacy, its owners, staff or other affiliates do not take any responsibility for errors in these sources. Patients should not rely on the facts or opinions in the content to manage their own health, and should seek the advice of an appropriate medical professional. Further, the opinions or facts in the content do not reflect the opinions and beliefs of the pharmacy, its owners, staff or other affiliates.

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