70% effective vaccine is not why you have a 30% chance of catching it

Pfizer and Moderna are 90% effective, Astrogenene 70% effective and Johnson & Johnson 67% effective. This leaves many readers wondering about it. ” The advantage of taking the risk of vaccination is when there is a 30% chance of contracting the diseaseLady 2.

Except that this is untrue: we cannot calculate the effectiveness of the vaccine by comparing the number of infections in the vaccinated population. 70% effective vaccine means that in a group of unwanted people who have been diagnosed with 100 cases of disease, you will only have 30 if each person is vaccinated. What measures the effectiveness of a vaccine, therefore, is not the number of people who develop the disease, The risk of developing the disease is lower compared to the unvaccinated population.

About Kovid, when we say for example AstraZeneca “70% effective against Kovid-19”, During the outbreak of the virus, the vaccine reduces the risk of developing the symptomatic form of the disease by 70% compared to the control group that did not receive the vaccine. Not to mention that a wide variety of effects can be put forward: hence, the effectiveness of Johnson & Johnson’s vaccine is usually 67%, but it increases to 85% when we focus on the prevention of serious diseases.

After the main tests

Effect of vaccine Recruiting thousands of volunteers, calculated at the end of the big trials Describe our colleagues from the daily Le Monde. Half of the participants will be vaccinated, the other half placebo. It will wait until as many people as possible are infected with the disease who can do statistical analyzes. The effectiveness of the vaccine is estimated according to the number of cases identified in each group (vaccination against placebo). The international consensus for vaccines against COVID-19 prescribes at least a 50% effective limit. On average, this is equivalent to the effectiveness rate (40-60%) of seasonal influenza vaccines.

However, what is the risk of catching Kovid if I am vaccinated?

Vaccination does not completely prevent the virus from infecting, but it does not cause symptoms or they are mild. Therefore, every winter, people who have been vaccinated against the seasonal flu are still infected with the flu, but in most cases they are on a more careful route than if they had not been vaccinated.