to outweigh large studies involving thousands of people.

I don't think the studies conclude that there are no adverse reactions. In fact, I think I recall being warned that there is a probability of a reaction. This site corroborates the first-hand and second-hand emprical data I've collected. Including yours, just now, for example a similar thing happened to my father when he took a pneumonia vaccine and the flu vaccine together this year, though it had never happened before. Also, I've lost my voice after taking the flu shot each time, and this has happened to my mother-in-law as well. I'm heartened to see that 'hoarseness' is a listed symptom.