Paxlovid Has Hospitalization, Mortality Benefits Among the Vaccinated

One of the many questions hovering over Paxlovid (ritonavir-boosted nirmatrelvir) is how much of a difference the antiviral treatment medication makes in people who have been vaccinated against COVID-19. The clinical trials that led to the FDA authorizing the medication that showed Paxlovid had a large effect on COVID-19 severity did not include people who were vaccinated.

The question hasn’t been fully answered but some evidence is coming in.

In June, Pfizer issued a press release about interim results from its EPIC-SR trial of Paxlovid that mentioned a sub-group analysis of 721 vaccinated adults with at least one risk factor for severe COVID-19. The press release said that Paxlovid led to a 57% reduction in hospitalization or death in that vaccinated group, although the difference didn’t meet the statistical standards for showing a real difference.

More recently, the research arm of Epic, the electronic health record company headquartered in Verona, Wisconsin, shared results showing large differences in hospitalizations and deaths between those treated with Paxlovid and those who hadn’t been treated with Paxlovid among people who had been vaccinated. The differences were larger among those 65 and older. But the Epic research also showed a difference in the 50-64 age group.

For example, there 27 hospitalizations (0.13%) and zero deaths among 20,407 peoplein that age who were treated with Paxlovid and who had been fully vaccinated and had had a booster. Among the 38,689 adults in the fully vaccinated, boosted group who were not treated with Paxlovid there were 143 hospitalizations (0.37%) and seven deaths (.02%). That works out to a hospitalization rate that is almost three times higher among those not treated with Paxlovid compared with those that were.

Jacqueline Gerhart, vice president of informatics at Epic, noted that research findings from Israel had suggested that Paxlovid didn’t make a difference in the 50-64 age group. But that was a smaller study than the one conducted by her and her colleagues that might not have the statistical power to detect a difference. The size of Epic’s database, called Cosmos, is an advantage.

“On first look at these numbers, we not only saw a difference, but it was statistically significant, meaning that the confidence intervals didn't overlap, meaning that we could be very confident that there actually benefit to taking Paxlovid between age 50 and 64,” Gerhart said in an interview.

Gerhart also looked at the hospitalization and mortality benefits of Paxlovid among those who were vaccinated but not boosted and those were vaccinated and double boosted. The results showing Paxlovid as protective against hospitalization and death were similar. The Epic researchers did not, though, break out Paxlovid results for people who are not vaccinated.

“We weren’t trying to say how much better protected you are being vaccinated and taking Paxlovid. We were trying to say, if you have already been vaccinated, is there still benefit to taking Paxlovid. And the answer is yes,” said Caleb Cox, an Epic Research lead.

Paxlovid has become the dominant form of treatment for COVID-19 in the United. According to a tally by HHS, 5.2 million doses have been administered between the Dec. 7, 2021,and Oct. 9, 2022.

This story originally appeared in Managed Healthcare Executive.