Covid-19: How the largest vaccine efficacy study was conducted

It is in France where the largest study on the efficacy of anti-life vaccines was carried out, with 22 million people included. It shows that vaccination against Covid-19 reduces the risk of hospitalization and death by 90% in people over 50 years of age. Une analyze effectuée par le groupement d’intérêt scientifique public Epi-Phare, who on doit also des travaux poussés sur les factors de risque du Covid-19, ou the case of the consommation d’anxiolytiques et d’antidépresseurs depuis le debut de the crisis. Its director, Prof. Mahmoud Zureik, explains to L’Express the specificities of this unique structure, created by bringing together the teams to which we owe historical analyzes of all the public health scandals of recent years – Mediator, Dépakine, Essure , Androcur …

L’Express: What does the work of Epi-flagship contribute to the efficacy of the vaccines against vaccines compared to all those already published?

Mahmoud Zureik: So far, the largest study available, conducted by an Israeli team, included 6 million people. For our part, we were able to take into account 11 million vaccinated subjects and 11 million unvaccinated subjects. This gives an almost exhaustive picture of the effectiveness of injections in real life, with a highly accurate result: a bit like when you do a poll and then a referendum. Furthermore, this very large population allowed us to compare the results obtained by three vaccines, where the other studies were only able to follow a maximum of two. We also confirmed on this occasion that the injections from Pfizer, Moderna and AstraZeneca all had a similar level of effectiveness, and very high, against the risk of hospitalization and death from Covid.

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Recently a controversy has arisen in social networks, some have been surprised by a number of subjects older than 75 included above the real population in this age group …

Actually, there is no cause for debate. People can be counted twice because they sometimes change their vaccination status during the study, going from the unvaccinated group to the vaccinated group (and thankfully). The Israeli study used the same methodology, classic and proven in epidemiology, fully accepted by the scientific community.

How does Epi-flagship work?

We have access, with the necessary regulatory authorizations, to anonymized databases of hospitals and Health Insurance, through the National Health Data System (SNDS). It gathers all the procedures, consultations, and prescription of reimbursed medicines of 67 million insured of the social security since 2006. It is a unique database in the world. Our scientists, who have strong skills in pharmacoepidemiology, data management, biostatistics, apply big data techniques to conduct studies on the use, efficacy and safety of medical devices in order to enlighten public authorities and society.

“The idea was to provide the State with an autonomous and reactive public expertise in the field of epidemiology of medical devices”

After the Ombudsman scandal, Medicare and ANSM had each created a pharmacoepidemiology service, which they merged in 2018 after working closely for more than ten years. This is the work that had confirmed the link between this drug and heart valve disease, after having quantified the number of deaths attributable to it. We have worked together, the Health Insurance and the ANSM, on all the highly publicized topics in recent years: the adverse effects of combined oral contraceptives, depaquine, HPV vaccines, Essure devices, progestin treatments in relation to meningiomas …

What links do you have with the administrations of your country and with the ministry on such sensitive issues?

The idea was to provide the State with autonomous and reactive public expertise in the field of epidemiology of medical devices (drugs and medical devices). We’re seen as a bit like the “GIGN” of drug crises – it’s about being able to quickly answer any question by conducting reliable and robust scientific studies. Of course, the question of independence is crucial: here no one has any connection to the pharmaceutical industry, not even a coffee or a meal. And we work with total independence from public authorities, who never intervene in conducting studies and interpreting results. As for me, I am an academic, so I have no hierarchical relationship with these two administrations.

“The objective of this proactive surveillance is to avoid a health crisis”

How do you choose your subjects?

Public decision-makers can ask us questions related to crisis situations, but we can also act. During the Covid epidemic, our data confirmed the deficit in childhood vaccination, the very marked decrease in the use of antibiotics or even the least recourse to various acts that required the physical intervention of a healthcare professional (magnetic resonance imaging, colonoscopy, …) . We also did studies on hydroxychloroquine. Outside of Covid, we proactively monitor the products most consumed by the French: proton pump inhibitors (heartburn treatment), statins, antihypertensives … The objective of this proactive monitoring is precisely to avoid health crises .

Mahmoud Zureik is a professor of epidemiology and public health.  He is also the director of EPI-PHARE, a specialized public knowledge structure in pharmacoepidemiology.

Mahmoud Zureik is a professor of epidemiology and public health. He is also the director of EPI-PHARE, a specialized public knowledge structure in pharmacoepidemiology.

Mahmoud Zureik for L’Express

Can you use the data to identify hitherto unknown side effects on a particular health product?

No, we do not do data mining, otherwise we run the risk of working in a vacuum and finding nothing or finding random associations by mistake. We always act on the basis of weak signals: feedback from the field, scientific publications, pharmacovigilance alerts … Our work confirms or invalidates these signals. For example, regarding the new direct-acting oral anticoagulants, we had shown that there was in fact no increased risk of bleeding compared to conventional anti-vitamin K treatment, which has since been confirmed by various scientific publications.

Are there any limits to your work, for example with information that is not available in the database?

In fact, some important points are not included, such as the weight of the patients or details about their social characteristics. We do not have the city’s medical diagnoses, but we have indirect information on this subject, for example through the treatments carried out by the insured. But there are also questions that we cannot answer due to the limitations of this data. For example, we have seen a pharmacovigilance signal on a subcutaneous contraceptive that can migrate to the lung. We wanted to do a study on this topic, but we realized that there were no valid codes at the hospital base for identification and surgical intervention related to the possible removal of this device. Therefore, we were unable to push further investigations.

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Excluding covid, what issues are you currently working on?

On a wide variety of topics, from the safety of proton pump inhibitors and biosimilars to inappropriate prescribing in the elderly, to studying the efficacy of Prep, the pre-exposure prophylaxis against HIV, in real life, or drug use analysis. During pregnancy. Of course, all of our study reports are intended to be published on our site and subsequently published in international peer-reviewed scientific journals.

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