Paxlovid, an oral antiviral treatment for COVID-19, has been widely used to reduce the risk of severe disease, especially during the Omicron variant surge. While initial clinical trials showed strong benefits in unvaccinated adults, recent real-world studies have raised questions about its effectiveness in vaccinated older adults. Understanding Paxlovid’s role in preventing hospitalization and death among high-risk populations, including those under 65, remains critical as COVID-19 continues to evolve1 2.
Paxlovid Recommendations for High-Risk Patients Under 65
Paxlovid is authorized for emergency use in individuals aged 12 and older who are at increased risk of severe COVID-19, including those with mild-to-moderate symptoms who have tested positive for the virus3 4. This broad eligibility includes younger adults with underlying health conditions or weakened immune systems that elevate their risk for progression to severe disease3 4. Although Paxlovid shows the greatest benefit in older adults, its use in younger high-risk patients is still considered valuable based on individual risk assessments4 5.
“Since the strongest predictor of severe COVID-19 is advanced age, it has been crucial to obtain evidence on whether the results of the Pfizer trials generalized to older and vaccinated populations.”
— John Mafi, MD, University of California Los Angeles2
A large real-world study during the Omicron period in the United States found that Paxlovid was associated with a 70% reduction in hospitalization risk among high-risk adults, particularly those aged 50 and older4 5. However, the benefit in younger adults under 65 is less clear and may depend on specific risk factors such as chronic illnesses or immunosuppression4 5. Clinical decisions about prescribing Paxlovid should therefore be personalized, considering the patient’s overall risk profile and potential drug interactions3 .
Key risk factors for severe COVID-19 that justify Paxlovid treatment include:
- Age 50 years or older, with the highest risk in those 65 and above3 4
- Chronic conditions such as diabetes, heart disease, chronic lung or kidney disease3
- Immunocompromised status due to medical treatments or conditions3
- Obesity and other metabolic disorders3
- Pregnancy or recent pregnancy within six weeks3
💡 Did You Know?
The use of Paxlovid in elderly patients may promote recovery from COVID-19 and reduce viral load without adverse events6 .
Despite its authorization for younger high-risk groups, Paxlovid’s strongest evidence of effectiveness remains in older adults. For example, a retrospective cohort study in Israel during the Omicron surge showed that among patients aged 65 and older, Paxlovid treatment reduced hospitalization rates by approximately 73% and death rates by 79% compared to untreated patients1 . In contrast, no significant benefit was observed in adults aged 40 to 64 years1 .
| Age Group | Hospitalization Rate (per 100,000 person-days) | Adjusted Hazard Ratio for Hospitalization | Death Rate (Adjusted Hazard Ratio) |
|---|---|---|---|
| ≥65 years (treated) | 14.7 | 0.27 (95% CI, 0.15 to 0.49) | 0.21 (95% CI, 0.05 to 0.82) |
| ≥65 years (untreated) | 58.9 | Reference | Reference |
| 40–64 years (treated) | 15.2 | 0.74 (95% CI, 0.35 to 1.58) | 1.32 (95% CI, 0.16 to 10.75) |
| 40–64 years (untreated) | 15.8 | Reference | Reference |
| Sources: 1 | |||
This data underscores the importance of prioritizing Paxlovid treatment for older adults and high-risk individuals, while still considering younger patients with significant risk factors1 .
“Since the study found no significant effect on COVID-19 hospitalizations and deaths among vaccinated older adults, our findings underscore the urgent need for further randomized-clinical trials investigating Paxlovid’s effects in higher-risk populations, such as older subgroups who are frail or immunosuppressed.”
— Katherine Kahn, MD, University of California Los Angeles2
Paxlovid Efficacy and COVID-19 Rebound
COVID-19 rebound refers to the recurrence of symptoms or a new positive viral test after initial recovery. This phenomenon has been observed in patients treated with Paxlovid as well as those who did not receive antiviral therapy7 45. Importantly, rebound cases are generally mild and not associated with severe illness or increased risk of hospitalization7 45.
Research indicates that COVID-19 rebound occurs independently of Paxlovid treatment or vaccination status, suggesting it may be part of the natural course of SARS-CoV-2 infection in some individuals7 45. The Centers for Disease Control and Prevention (CDC) clarifies that experiencing rebound symptoms does not imply the development of resistance to Paxlovid and does not diminish the drug’s effectiveness in preventing severe outcomes7 45.
There is currently no evidence supporting longer or repeated courses of Paxlovid to manage rebound cases7 45. Most patients recover fully without additional antiviral treatment.
While Paxlovid has demonstrated clear benefits in unvaccinated older adults, recent studies suggest its effectiveness in vaccinated older adults may be more limited. A large observational study in Ontario, Canada, exploited an age-restrictive policy that limited Paxlovid access to adults aged 70 and older. This natural experiment showed that despite a 118% increase in Paxlovid prescriptions at age 70, there was no significant reduction in COVID-19-related hospitalizations or all-cause mortality among vaccinated older adults8 29.
“Our study effectively rules out the notion that Paxlovid causes large reductions in COVID-19 hospitalization in vaccinated older adults.”
— John Mafi, MD, University of California Los Angeles8
The study found Paxlovid’s effect on hospitalization in vaccinated older adults to be approximately four times weaker than that reported in Pfizer’s original clinical trial, which focused on unvaccinated middle-aged adults8 2. This suggests that while Paxlovid remains an important tool, its impact in highly vaccinated elderly populations may be modest.
Recent research on Paxlovid’s role in preventing long COVID (post-acute sequelae of COVID-19) shows limited benefit overall, with a small protective effect observed only in patients aged 65 and older10 . For example, one large cohort study found an absolute risk reduction of just 0.43% in long COVID incidence among older adults treated with Paxlovid, indicating that many patients would need treatment to prevent a single case of long COVID10 .
- COVID-19 rebound symptoms can occur with or without Paxlovid treatment and are usually mild7 45.
- Paxlovid remains effective in reducing hospitalizations and deaths, especially in older adults and unvaccinated populations4 51.
- The benefit of Paxlovid in vaccinated older adults is less pronounced and requires further study8 2.
- There is no current evidence to support extended or repeated Paxlovid courses for rebound cases7 45.
