The following is a summary of “Effectiveness of nirmatrelvir–ritonavir in preventing hospital admissions and deaths in people with COVID-19: a cohort study in a large US healthcare system,” published in the June 2023 issue of Infectious Diseases by Lewnard et al.

In the United States, nirmatrelvir–ritonavir is approved for use in patients 12 years or older with mild-to-moderate COVID-19 at risk of severe disease progression and hospitalization. Researchers sought to determine the efficacy of nirmatrelvir–ritonavir in preventing hospitalizations and deaths in persons with COVID-19 receiving outpatient prescriptions in the United States. In this matched observational outpatient cohort study in the Kaiser Permanente Southern California (CA, USA) healthcare system, data were extracted from the electronic health records of non-hospitalized patients aged 12 years or older who received a positive SARS-CoV-2 PCR test result (their index test) between April 8 and October 7, 2022, and who had not received another positive test result within the previous 90 days.

They matched cases by date, age, sex, clinical status (including care received, the presence or absence of acute COVID-19 symptoms at testing, and the time from symptom onset to testing), vaccination history, comorbidities, healthcare seeking during the previous year, and BMI to compare outcomes between those who received and did not receive nirmatrelvir–ritonavir. Their primary objective was to estimate the efficacy of nirmatrelvir–ritonavir in preventing hospitalization or mortality within 30 days of a positive SARS-CoV-2 test. Their study included 7,274 nirmatrelvir–ritonavir recipients and 126,152 non-recipients with positive SARS-CoV-2 testing. Within 5 days of symptom onset, 5,472 (75.2%) treatment recipients and 84,657 (67.1%) non-recipients were tested. 

The estimated efficacy of nirmatrelvir–ritonavir in preventing hospital admission or mortality within 30 days of a positive SARS-CoV-2 test was 53.6% (95% CI: 6.6 to 77.0%) and increased to 79.6% (33.9% to 93.8%) when administered within 5 days of symptom onset. The estimated efficacy of nirmatrelvir–ritonavir in the subgroup of patients tested within 5 days of symptom onset and whose treatment was dispensed on their test day was 896% (range: 50.2–97.8). Nirmatrelvir–ritonavir effectively reduced the risk of hospital admission or mortality within 30 days of a positive outpatient SARS-CoV-2 test in an environment with high COVID-19 vaccination rates.

Source: sciencedirect.com/science/article/pii/S1473309923001184