I want to know the answer to the following question:
When had Nigeria not had a reported polio case in 6 months for the first time?
All the background I'm provided with is that "However, a major breakthrough came in December 2014, when it was reported that Nigeria hadn't recorded a polio case in 6 months, and on its way to be declared Polio free.". Is that enough to answer the question?
Answer: yes