Not really, it's dropped for the following reasons.
1. Rick finds out that everyone is infected and all will turn upon death regardless of the cause of death.
2. The National headquarters for the CDC, the one most capable of finding a possible cure is destroyed.
3. The next nearest labs are in Washington DC, which is where Eugene was taking them, or Texas which is uncharted and wide open territory.
4. Lastly, it makes no sense for Rick and his people to work on finding a cure since none of them have the ability to research or synthesize one.