Is the MRNA rally over extended?

The stock has made an impressive move higher on the news of funding with the coronavirus backdrop. However, even if a vaccine is possible the development process is still in its infant stages. Recently, price took a dive and has been consolidating. Looking at a 30m scale, the 20 period moving average for volume has also taken a dive in the last few sessions and seems to fit tight with the price curve in recent trading. Combined with a bear flag I think price tests some of the lower fib lines in the near future. I'm hoping to see a low volume climb to the next fib level and rejection around that price level. I'll sell call spreads there in anticipation of further weakness. I choose to sell call spreads because if price decides to rapidly appreciate I can offload the short call and actively manage the long call to ideally mitigate any potential losses.