The U. S. Food and Drug Administration have still not given a green signal to Prevnar vaccine of Pfizer. This children’s vaccine has been developed to fight pneumonia and meningitis, but it seems that the regulator is not happy with the vaccine just as yet.

Pfizer obtained this vaccine from Wyeth, after acquiring Wyeth for $67 billion. Now, Pfizer wants FDA’s acceptance to market Prevnar 13 as a vaccine for infants and toddlers.

"We remain confident that the data in the (application) support the approval of Prevnar 13. We will continue to work closely with the FDA to help expedite the completion of its review”, said Emilio Emini, Pfizer's Chief Scientific Officer for Vaccine Research.

In May, Prevnar 13 was granted a priority review, but in August, this deadline was extended to December 30. The European Commission also approved Prevenar 13 earlier this month and the vaccine is now approved for use in infants and young children in 34 countries.

Analysts are predicting the sale of this product to rise to $4 billion a year by 2013.

Shares of Pfizer were at $18.45 falling 0.3%.