Paxlovid (nirmatrelvir-ritonavir) provides protection against hospitalization in high-risk adults with COVID-19, including those who are vaccinated, according to a study in Clinical Infectious Diseases.
The retrospective analysis sought to estimate the stepwise benefit of monovalent vaccination and Paxlovid for preventing COVID-19 hospitalization.
Data were obtained from the Cosmos dataset, which included more than160 million individuals using health care in the US. Eligible participants were nonpregnant adults who were either aged 50 and older or at least 18 years of age with an underlying health condition associated with documented severe COVID-19 disease progression.
The patients were diagnosed with COVID-19 in an outpatient encounter from April 1, 2022, to August 31, 2022. They were counted as having received Paxlovid if it was prescribed within 5 days after their COVID-19 diagnosis; vaccination status was categorized on the date of their diagnosis. A referent group included unvaccinated individuals who did not receive nirmatrelvir-ritonavir.
The primary outcome was COVID-19 hospitalization within 30 days after diagnosis.
Of 731,349 patients diagnosed with COVID-19 and eligible to receive Paxlovid, 177,757 patients (24.3%) were unvaccinated, 157,011 (21.5%) received 2 mRNA vaccines, 330,448 (45.2%) received 3 or more mRNA vaccines, and 66,133 (9.0%) were classified as “other” with respect to vaccination status. Paxlovid was received by 35,826/141,931 (20.2%) of participants who were unvaccinated, 42,355/157011 (27.0%) of participants who received 2 mRNA doses, and 130,778/330,448 (33.0%) of participants who had received at least 3 mRNA vaccine doses.
A total of 5296 of 731,349 patients (0.72%) with COVID-19 were hospitalized within 30 days of diagnosis. The hospitalization rate in those without treatment or vaccination was 31.1 per 100,000 person-days, compared with 27.0 per 100,000 person-days in untreated participants with 2 mRNA vaccine doses, and 28.1 per 100,000 person-days in untreated participants with 3 or more mRNA vaccine doses.
After receiving nirmatrelvir-ritonavir, the hospitalization rate was 19.7 per 100,000 person-days in patients who were unvaccinated, 16.4 per 100,000 person-days in those who had 2 mRNA vaccine doses, and 14.2 per 100,000 person-days in those with 3 or more mRNA vaccine doses. The patient group receiving Paxlovid and 3 or more mRNA vaccine doses had an estimated 16.9 fewer hospitalizations per 100,000 person-days compared with the patient group made up of those who were unvaccinated and untreated.
In a comparison with unvaccinated patients who did not receive COVID-19 treatment, the COVID-19 hospitalization rate was reduced in patients who were vaccinated but did not receive nirmatrelvir-ritonavir (2 mRNA doses, adjusted hazard ratio [aHR], 0.74; 95% CI, 0.67-0.80; ≥3 mRNA doses, aHR, 0.51; 95% CI, 0.47-0.55) and those who were unvaccinated but after receiving nirmatrelvir-ritonavir (aHR, 0.47; 95% CI, 0.40-0.55). In patients who received treatment and were vaccinated, the hospitalization rate was decreased further (2 mRNA doses and nirmatrelvir-ritonavir (aHR, 0.33; 95% CI, 0.29-0.39), with the lowest COVID-19 hospitalization rate occurring in patients who had 3 or more mRNA vaccine doses and nirmatrelvir-ritonavir (aHR, 0.22; 95% CI, 0.19-0.24).
Some study limitations are the inclusion of only adults who had COVID-19 between April and August 2022, and the exclusion of the timing of a patient’s last vaccination, which may have affected that patient’s risk for hospitalization.
“While the burden and impact of COVID-19 in future respiratory seasons are to be seen, the combination of vaccination and oral antiviral treatment for eligible patients remains an important tool against COVID-19 hospitalization and death,” the investigators stated.
Disclosure: Some of the study authors declared affiliations with a software company. Please see the original reference for a full list of authors’ disclosures.
