Not all weapons developed during the pandemic are equally effective. The vaccines, for example, have confirmed their usefulness in an unequivocal way, significantly reducing the danger of the virus, and therefore hospitalizations and deaths, at least for the elderly and patients at risk. The same cannot be said of the antiviral Paxlovid, one of the two drugs approved against Covid 19, who, in the face of a very high cost and millionaire investments by health systems such as ours (only in 2023 it cost us as many as 54 million euros), to proof of the facts is the expectations. The last rejection comes from a recent study published in Jama, in which the drug has not shown that it can reduce the hospitals or the deaths in elderly patients vaccinated against Sars-Cov-2, the largest population for which its use is indicated.
The drug is a combination of two antiretroviral molecules, Nirmatrelvir and ritonavir. It was developed as anti -Covid therapy 19 in 2020, and used all over the world first with emergency authorization, and then with definitive approval starting from 2022. In Italy it is refunded by the National Health Service for the early treatment of patients at risk, at a price that – without taking into account the discounts negotiated by AIFA with the manufacturer – exceeds 1,300 euros per patient.
The data that led to the approval of this pharmaceutical blockbuster (which has generated revenues for tens of billions of dollars in the last three years) come from a study of 2022, which had tested (conveniently) its effectiveness on unvaccinated patients, demonstrating a certain ability to reduce hospitalizations and deaths in this category of people. From the beginning, the selection of the population on which to test the drug had somehow seemed a “convenient” choice, given that the lack of vaccination exposes to more serious forms of illness, and therefore increases the chances that a drug can make the difference, and that the vaccinated at the time of the study were already very widespread in the whole world, and would have represented a more representative study population than it was (or would have been there anyway global.
A second study, from 2024, has therefore tested Paxlovid’s effectiveness again in middle -aged people, without finding any significant reduction in the risk of hospitalization or death. The rational for its use was therefore much less convincing, especially in the face of the very high cost of therapy, and two annoying, as common, side effects: a terrible dysgeusia, that is, a “flavor” constantly present in the mouth that can last for several days, and the viral rebound, the tendency of the virus to return to replicate in the body after disappearing for a few weeks following the consequent extension, the duration of the infection.
However, the hope remained that the drug could be useful also following the vaccination, at least in the elderly patients, more fragile and therefore at the risk of developing serious forms of Covid 19. To verify it, the authors of the new study were able to exploit a fortuitous “natural experiment” born from a change of legislation in the Canadian province of the Ontario: from April 1, 2023, in fact, the prescription of the drug has been restricted to patients over 70, and therefore checking the patients. The exist of the infections that occurred just above, and just below that age threshold, the researchers of the University of California in Los Angeles were able to verify the effectiveness of Paxlovid in elderly patients (over 70) vaccinated, comparing it with the outcome of the infections in elderly patients (just below 70) vaccinated who have not received additional therapies. The results, we said, gave a negative response: the differences in terms of hospitalizations and mortality are minimal, if not non -existent.
“Our study essentially excludes the possibility that Paxlovid can induce a consistent reduction in hospitalizations for Covid 19 in elderly and vaccinated patients,” underlines John Mafi, professor of internal medicine of the University of California in Los Angeles who participated in the research. “We cannot completely exclude that there is a small reduction in hospitalizations for Covid, but our results indicate that at best the potential effect of Paxlovid is four times lower than that reported in the original Pfizer trial of 2022”.