General information, not an individual diagnosis. Ask a healthcare professional if you are unsure about your situation.
Relative risk reduction expresses the fall in risk as a proportion of the reference group’s risk: the risk difference is divided by the reference risk. It does not mean the share of all people who would be protected.
Absolute risk reduction subtracts the study group’s risk from the reference group’s risk. When risks are percentages, the difference is expressed in percentage points; it can also be shown as cases per 1,000 people.
An example in the 2025 HAS report concerns a trial conducted in 2011-2013 among people aged 65 and over: it compares a high-dose flu vaccine with a standard vaccine. Both groups are vaccinated; the outcome is laboratory-confirmed flu.
Table 7 gives rounded anticipated risks of 1.9% with the standard vaccine and 1.4% with the high-dose vaccine. These correspond to 19 and 14 cases per 1,000, a difference of 0.5 percentage points or 5 cases per 1,000 in this context.
The same table reports a relative estimate of 24%, with a confidence interval of 11-36% and moderate certainty of evidence. The displayed absolute risks are rounded: their ratio cannot reproduce that relative estimate exactly.
Before applying a figure to your situation, ask which groups, starting risk and follow-up period were studied. These older results do not predict your personal benefit for 2026-2027; the same relative percentage can correspond to different absolute differences when the starting risk changes.
Sources
Vaccination
Flu and Covid-19: the 2026–2027 campaign
The national flu and Covid-19 vaccination campaign starts on 13 October 2026. In Doctolib, choose “Vaccination antigrippale (Grippe)” or “Vaccination COVID-19” for the vaccination you want to discuss.
Bring your carte Vitale and, for flu, your coverage voucher if you have one. The professional checks the recommendations and coverage conditions that apply to you.
The pharmacy checks whether vaccination and coverage apply based on the vaccine, your age and your circumstances.
Assurance Maladie — Campagne grippe 2026–2027 (9 octobre 2026) · Assurance Maladie — Campagne Covid-19 (30 septembre 2026) · Assurance Maladie — Vaccination par le pharmacien · Assurance Maladie — Prise en charge des vaccins · Ministère de la Santé — Calendrier vaccinal
Your health review
Review your health
Mon bilan prévention is an appointment to discuss your habits and choose your health priorities. Review the four age groups and practical information.