Outcomes of COVID-19 treatment with Paxlovid

In a recent study posted to the medRxiv* preprint server, researchers investigated the outcomes of coronavirus disease 2019 (COVID-19) treatment with paxlovid.

Study: Describing COVID-19 Patients During The First Two Months of Paxlovid (Nirmatrelvir/Ritonavir) Initiation in a Large HMO in Israel. Image Credit: Cryptographer/Shutterstock
Study: Describing COVID-19 Patients During The First Two Months of Paxlovid (Nirmatrelvir/Ritonavir) Initiation in a Large HMO in Israel. Image Credit: Cryptographer/Shutterstock

Treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in its early phases is currently achieved by administering convalescent plasma and biclonal or monoclonal antibodies intravenously. However, there is no orally available treatment method present to prevent disease severity in high-risk patients.

About the study

In the present study, the team assessed the impact of paxlovid treatment on SARS-CoV-2 disease outcomes and healthcare resource utilization (HCRU).

The team used retrospective and observational data from the Maccabi healthcare services (MHS) database to identify SARS-CoV-2 patients between 1 June 2021 and 28 February 2022. The data obtained from the MHS database included information regarding the patient’s demographics, comorbidities based on ICD-9 codes, the status of immunocompromise, dates of SARS-CoV-2 polymerase chain reaction (PCR), and formal antigen tests, medications, history of hospitalization, and death. Information regarding COVID-19 symptoms was collected via a questionnaire provided to the participants.

The study involved patients who had at least one SARS-CoV-2-positive reverse transcription PCR (RT-PCR) test or a positive rapid antigen test during the period of identification. These eligible patients were divided into the following cohorts: (1) pre-paxlovid period: patients who tested positive between 1 June 2021 and 30 November 2021 when the dominant variant in Israel was SARS-CoV-2 Delta and paxlovid was not available for treatment and (2) paxlovid period: patients who tested SARS-CoV-2 positive between 2 January and 28 February 2022 when paxlovid was available for treatment in Israel. This category was further sub-classified into (a) paxlovid-treated: SARS-CoV-2 patients who received paxlovid treatment and (b) paxlovid-untreated: SARS-CoV-2 patients who were offered paxlovid treatment but declined. A total of 20,284 patients from the pre-paxlovid period and 10,030 from the paxlovid period were eligible for paxlovid treatment

The index date for patients from the paxlovid treated group was the date when paxlovid was first dispensed, while that for the paxlovid untreated patients was the date the paxlovid treatment was declined. For patients belonging to the pre-paxlovid period, the index date was the average number of days from the date of the first COVID-19 positive test to the date of the paxlovid administration. The resulting number of days was added to the date of the first positive SARS-CoV-2 RT-PCR test or the formal antigen test of the patients from the pre-paxlovid period.

Patients eligible for paxlovid treatment were either aged 70 years and above irrespective of their risk score, aged between 50 to 69 years and had a risk score of two points or more, or aged between 12 to 49 years and had a risk score of four points or more. The COVID-19 risk score point system combined the age and disease characteristics to yield a numerical score ranging from zero to four, where four represented the highest risk of disease progression to severe COVID-19.         


Almost 10% of the paxlovid-treated, 25.9% of the paxlovid untreated, and 22.9% of the pre-paxlovid period patients were unvaccinated, while most of the participants had no history of SARS-CoV-2 infection. The mean time duration from the first SARS-CoV-2-positive test to paxlovid treatment was 1.8 days.

A COVID-19 hospital risk score of four was observed in 87.2% of the untreated group, 69% of the paxlovid-treated group, and 64.7% of the pre-paxlovid period group. Additionally, a minimum of one COVID-19 symptom was reported by 74% of the treated, 64% of the untreated, and 81% of the pre-paxlovid period cohorts. Notably, fever and cough were observed in 27.7% and 45% of the paxlovid untreated group, 35.5% and 56.4% of the paxlovid treated group, and 80.6% and 45% of the pre-paxlovid period group, respectively. Moreover, anosmia was reported by 17.8% of the pre-paxlovid, 3% of the paxlovid-treated, and 2.7% of the paxlovid untreated groups.

Notably, the patients from the paxlovid period were more likely to be older than those in the pre-paxlovid period. The number of patients aged 70 years and above was higher in the paxlovid-treated and the paxlovid-untreated groups than those in the pre-paxlovid period group.  

Overall, the study findings showed that paxlovid sufficiently lowered the risk of COVID-19 disease severity. The study also highlighted the potential comparability among patients who tested positive for SARS-CoV-2 and supported further analyses by recognizing key aspects for future comparative studies. 

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Bhavana Kunkalikar

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.


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