According the www.fda.gov, a HUD/HDE application has 75 days to be responded to, and an IDE has 30 days (which I assume is superceeded by the HUD application and thus why we haven't heard something official yet)..
So may take longer than 5 days (and if for some unlikely reason the answer is "needs more info", again we could be in limbo for a while more still)..
The only reason it has dropped is biotech traders are impatient. They like to move to the ones that are hot, and right now there's some really hot bio's moving up fast. I myself put a buy in at 2.10 today to add shares but it didn't drop that low so I bought ZLCS and ISR at the end of the day. But I'm staying long on NVIV, because it could make a really nice move once FDA approves human trials, and if the trials are successful, it will be enormously huge biotech news. Right now is a great buy in point if you don't have any imo.