# How is the decision for recommending a vaccine reached

There is an ongoing discussion about the use of the AstraZeneca covid-19 vaccine (Vaxzevria) in Europe. Some countries like Germany restrict the use of this vaccine, some - like Austria - do not.

How do the national vaccination boards (or similar institutions) reach this decision? I am not only interested in COVID-19, but in general. Europe and world-wide.

I imagine the process to be quite simple and something like this:

``````x = risk of a "serious" case of the illness
a = risk of getting infected
y = risk of having a "serious" negative reaction to the vaccine
Z = some constant, that need to be decided

if (x * a > y * Z )
then -> recommend vaccination
else -> do not
``````
• Is this a sensible approach? Why is there so much controversy?
• How is Z chosen in practice? Should it be 1, 10, 100, 1000...?
• How do you estimate the risk of getting infected in the first place (per month/year/life)?

I found some numbers from Austria here (German, December 2020, page 6): https://www.sozialministerium.at/dam/jcr:1bad4099-e0a4-4d91-a30d-a3e6d7827748/Kurzinformation%20f%C3%BCr%20Gesundheitspersonaldocx.pdf

which indicate a 1% chance of "serious" covid-19 cases for health workers, and a vaccination risk of less than 1:10000 So in this case we would have (assuming everybody gets covid):

``````0.01 * 1 >= 0.0001 * 100  (Z=100)
``````
• I think it's a lot more "people in a room talking" rather than something formulaic. It's people making decisions, not machines. – Bryan Krause Apr 2 at 17:06
• I am pretty sure that since the one that takes the final decision of a vaccine to be used is people who control the police of each country rather than doctors, scientists, it is not a decision based on scientific facts or numbers. – Christianidis Vasileios Apr 2 at 19:38
• @user21699 "People who control the police"? In most developed countries the decision on this sort of thing is made by a panel of doctors/scientists/public health experts. Facts and numbers can aid in decision making but they aren't sufficient by themselves, you need someone to interpret them. – Bryan Krause Apr 2 at 20:45
• I agree with above comments — but to indulge you — these statements are subjective ("Serious") is not well defined. There may not be enough information to estimate the potential risk to infection. There are problems with extrapolation, the future in the future you look, the less accurate our equations are. – Andrew Apr 3 at 21:38