Top 5 Takeaways

  1. Low Incidence of Severe Illness Post-Paxlovid: Hospitalizations or ED encounters for COVID-19 within 5-15 days after Paxlovid treatment were rare, occurring in <1% of patients, suggesting Paxlovid’s effectiveness in preventing severe illness.
  2. Study Population Characteristics: Among 5,287 Paxlovid recipients studied, 73% had received ≥3 doses of a COVID-19 vaccine, with a majority being female and having a median age of 61 years.
  3. Vaccination Status and Outcomes: The analysis revealed a higher proportion of COVID-19 related hospitalizations or ED encounters among unvaccinated or partially vaccinated individuals compared to the fully vaccinated.
  4. Clinical Implications: Paxlovid, when administered early, might reduce COVID-19-related hospitalization in individuals with mild to moderate infections at risk of progressing to severe disease.
  5. Study Limitations and Further Research: Limitations include the use of proxy indicators for COVID-19 severity and lack of a control group. The findings underline the necessity for more detailed studies to understand Paxlovid’s protective effects fully.

Original Article Author and Citation

Corresponding Author

Debbie E. Malden,

Suggested Citation

Malden DE, Hong V, Lewin BJ, et al. Hospitalization and Emergency Department Encounters for COVID-19 After Paxlovid Treatment — California, December 2021–May 2022. MMWR Morb Mortal Wkly Rep 2022;71:830-833. DOI:


This study analyzed electronic health records from a large healthcare system in California to assess the occurrence of severe COVID-19 illness requiring hospitalization or emergency department visits within 5-15 days after Paxlovid treatment. The findings indicate that severe illness post-Paxlovid treatment is infrequent, reinforcing the drug’s role in mitigating COVID-19 severity among treated patients.


The study reviewed health records of 5,287 individuals who received Paxlovid between December 2021 and May 2022, examining hospital admissions and emergency department encounters related to COVID-19 within the specified post-treatment period. Statistical analyses were conducted to understand the demographic and clinical characteristics of the patients and the outcomes of Paxlovid treatment.


The discussion highlights the significance of Paxlovid in potentially reducing hospitalizations among high-risk COVID-19 patients when administered early. It also notes the limitations of the study, including the absence of a control group and reliance on proxy measures for disease severity.


Paxlovid appears to be effective in preventing severe COVID-19-related illness in a real-world setting, with less than 1% of treated patients experiencing hospitalization or ED encounters shortly after treatment. The study underscores the need for further research to elucidate the full scope of Paxlovid’s benefits and its role in COVID-19 treatment strategies.

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