How effective is the booster really against Omicron? Very different results according to age
For those under 65: an effect especially on contamination
The finding is not at all the same for those under 65: if we examine the graphs above, whether in terms of deaths or hospitalizations, even in the ICU, the difference in incidence (= The number observed compared to the total number of people of this vaccination status and of this age group) is minimal between the people who received or three doses.
This does not mean that the booster has no effect: simply, among those under 65, the protection induced by the first two doses continues to be very effective against severe forms, even with time, and even with Omicron. Thus the reduction in the risk of going to care intensifies for 18-64 year olds who have received two doses of vaccine, remaining at 73%.
Since the baseline risk of a severe case is already lower for this age category, this leads to a minimal risk of‘1.7 vaccinated out of 100,000 only who goes to care intensifies. And this one is then often immuno-depressed or with heavy comorbidities. An extra dose does not change the essential game for people who do not react to the vaccine and do not produce antibodies.
But the effect of the booster can be seen on the other hand at the level of infections: it is reduced by 2 the risk of contamination compared to a person who has only received the first two doses, and therefore plays an important role in slowing down transmissions.