Can anyone understand WHO & FDA logic behind?

Many scientists voiced out that effective cures for COVID are available, eg: Ivermectin or hydroxychloroquine. These cures are only used on sick people. WHO & FDC caution against their use. In fact, there are fines and punishments in the US if doctors prescribe the cures.

U.S. doctors group sues FDA for limiting access to drug touted by Trump for COVID-19

mRNA vaccines are just experimental products that many death and injury cases are reported all over the world. In fact, vaccines can't prevent infection. They claim that it can prevent severe symptoms. Why can't they use effective medicines at the early stage? WHO & FDA don't concern about the vaccine's safety and side effects and push worldwide mandatory vaccination. Besides, why does CDC conceal the mortality and injury rate in the US?

What is the rationale behind it? Can WHO & FDA explain it?