According to the headlines the Pfizer vaccine is 90% effective.

However, there are a few qualifiers with that.

1. It doesn't prevent Covid, just reduces the severity

2. It's unknown if a vaccinated person is still contagious

3. It's unknown if it's safe for old people

4. It's unknown if it provides long term immunity

5. It's unknown if there are long term side effects

6. It's made with mRNA, meaning it's made of genetic material, which carries instructions to the body's immune system

I don't understand the mRNA bit well, but it sounds a bit creepy. Basically we will become genetically modified humans? Maybe that's fine - i don't know. This is the first time such a technique has been used to develop a vaccine.

The other point about mRNA vaccines is that they are tricky to store, needing to be kept at -80C. They are thawed before use but there's a short window in which they remain viable.

This adds a layer of logistics that will make distribution challenging.

Anyway, the stock market loved it!