No long term double blind flu vaccine studies.

The subject. What are the long term effects?....Unknown.

"I just did a PUBMED search with the phrase "Efficacy and effectiveness of influenza vaccines" and...

561 references!"

The terminology is restricted in the journals and on PUBMED, so that is no surprise

The majority of those studies don't have anything to do with actual effectiveness, Instead they are studies on "cost-effectiveness" or they deal with particular types of influenza vaccines on particular populations.

For example:

Safety and Efficacy of Neonatal Vaccination

Newborns have an immature immune system that renders them at high risk for infection while simultaneously reducing responses to most vaccines, thereby posing challenges in protecting this vulnerable population. Nevertheless, certain vaccines, such as Bacillus Calmette Guérin (BCG) and Hepatitis B vaccine (HBV), do demonstrate safety and some efficacy at birth, providing proof of principal that certain antigen-adjuvant combinations are able to elicit protective neonatal responses. Moreover, birth is a major point of healthcare contact globally meaning that effective neonatal vaccines achieve high population penetration. Given the potentially significant benefit of vaccinating at birth, availability of a broader range of more effective neonatal vaccines is an unmet medical need and a public health priority. This review focuses on safety and efficacy of neonatal vaccination in humans as well as recent research employing novel approaches to enhance the efficacy of neonatal vaccination.