Influenza vaccines are not that effective, that is a proven. It is because Polio virus and Influenza virus infect in very different ways.
Belshe RB, Mendelman PM, Treanor, et al.
The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenza virus vaccine in children. N Engl J Med. 1998; 338(20):1405-12.
Benowitz I, Esposito DB, Gracey KD, et al.
Influenza vaccine given to pregnant women reduces hospitalization due to influenza in their infants. Clin Infect Dis. 2010; 51(12):1355-61.
Ciszewski A, Bilinska ZT, Brydak LB, et al.
Influenza vaccination in secondary prevention from coronary ischaemic events in coronary artery disease: FLUCAD study. Eur Heart J. 2008 Jun; 29(11):1350-8.
Colquhoun AJ, Nicholson KG , Botha JL, Raymond NT.
Effectiveness of influenza vaccine in reducing hospital admissions in people with diabetes. Epidemiol Infect. 1997; 119(3):335-41.
Ferdinands JM, Olsho LEW, Agan AA, et al.
Effectiveness of influenza vaccine against life-threatening RT-PCR-confirmed influenza illness in US children, 2010-2012. J Infect Dis. 2014; 210(5):674-683.
Nichol KL, Baken L, Nelson A.
Relation between influenza vaccination and outpatient visits, hospitalization, and mortality in elderly persons with chronic lung disease. Ann Intern Med 1999; 130:397-403.
Phrommintikul A, Kuanprasert S, Wongcharoen W,et al.
Influenza vaccination reduces cardiovascular events in patients with acute coronary syndrome. Eur Heart J. 2011; 32(14):1730-5.
Talbot HK, Griffin, MR, Chen Q, et al.
Effectiveness of seasonal vaccine in preventing confirmed influenza-associated hospitalizations in community dwelling older adults. J. Infect Dis 2011; 203:500-8.
Talbot HK, Zhu Y, Chen Q, et al.
Effectiveness of influenza vaccine for preventing laboratory-confirmed influenza hospitalizations in adults, 2011-2012 influenza season. Clin Infect Dis. 2013; 56(12): 1774-7.
Udell JA, Zawi R, Bhatt DL, et al.
Association between influenza vaccination and cardiovascular outcomes in high-risk patients: a meta-analysis. JAMA. 2013; 310(16): 1711-20.