To calculate the effectiveness of a vaccine, many tests are performed on tens of thousands of people. These people are divided into two groups:
1) They are half vaccinated
2) The other half do not receive the vaccine (Placebo)
These people then return to their normal lives, and researchers examine them for several months for Corona infections. The Pfizer and Biotech vaccine trials, for example, involved 43,000 participants.
In the end, 170 people developed Corona infections. Which person in each of these two groups became infected with the virus determines the effectiveness of the vaccine.
• If 170 people who infected with Covid-19, are equally divided into two groups, this means that your chances of getting Covid-19 with the vaccine are the same as without the vaccine, so the effect of the vaccine is zero percent.
• If 170 infected patients are in the unvaccinated group and none of the vaccinated people are sick, then the effect of the vaccine will be 100%.
In the trial, which included 43,000 participants, there were 162 patients in the unvaccinated group and only 8 patients in the vaccinated group. This means that those who were vaccinated were 95% less likely to develop Corona infection ,so the vaccine was estimated to be 95% effective. This means that every person who is vaccinated when exposed to the Covid virus is 95% less likely to get the disease than a person without the vaccine, and ultimately the effectiveness of all types of vaccines approved and supplied is calculated in the same way.
But tests for each vaccine can be done under very different conditions. These vaccine performance numbers only tell what happened in the test of each vaccine and do not say what will happen in the real world.
Many researchers believe that these numbers are not a good yardstick for judging a vaccine because "preventing any infection is not the purpose of the vaccine."
John Hopkins University researcher Amel Adelja:
The goal of the vaccine is not necessarily to achieve zero percent Corona infection . Rather, the goal is to tame the virus and capture the virus' ability to cause serious illness, hospitalization, and eventual death.
The following figure will help you see the outcome of Corona infection in different ways:
The best condition is that you do not get sick at all (No Infection) and the worst case is death. These include cases such as hospitalization, severe to moderate illness, and asymptomatic illness.
At best, vaccines give you complete immunity, but that is not really the main purpose of the Covid vaccine.
"The real goal is to give the body the immunity it needs so that if you get the virus, instead of being hospitalized and having severe symptoms and eventually dying, your illness will be more like a mild cold that your immune system can handle, Confront and cope. That's what every approved vaccine does".
The main question is not which vaccine protects you against the Covid virus ...
But the fundamental question is which vaccine will keep you alive or prevent you from being hospitalized, or even which vaccine will help end the virus epidemic ...