Eurosurveillance
Volume 18, Issue 37, 12 September 2013
http://www.eurosurveillance.org/Public/Articles/Archives.aspx?PublicationId=11678

Research articles
The test-negative design: validity, accuracy and precision of vaccine efficacy estimates compared to the gold standard of randomised placebo-controlled clinical trials
by G De Serres, DM Skowronski, XW Wu, CS Ambrose

Laboratory-confirmed invasive meningococcal disease: effect of the Hajj vaccination policy, Saudi Arabia, 1995 to 2011
by Z Memish, R Al Hakeem, O Al Neel, K Danis, A Jasir, D Eibach