What have we learnt so far since end of 2019?

Is it ABC? 123? 一二三？HYPY? Spelling? 听写? How to cook or bake? How to grow plants in recycled water bottles or sew a bag using used tee?

We learnt that there's vaccine available in the market shortly after experimenting, not one but many.

We learnt that there're more than one jab, and there're boosters.

We learnt that the efficacy could well be negative not to say it's 95%.

Are all these safe? Any known or unknown side effects? Any injuries or maybe suspected deaths? Any discrimination? Any unfair treatment or criticisms? Any truth about the pseudo saline being used as placebo instead for the jab? How effective are the ART or PCR kits?