(1) Influenza vaccine is a short term vaccine. You need to repeat it no because the change of the virus every year but because the short effectiveness (from 2 to 5 months). In some in some years we have repeat exactly the same vaccine; «For 2014–15, U.S.-licensed influenza vaccines will contain the same vaccine virus strains as those in the 2013–14 vaccine».
(2) Influenza vaccine effectiveness is measured by the decrease of preventing outpatient medical visits due to laboratory-confirmed influenza and it is around 35-40%.
(3) Out of every 100 healthy adults vaccinated, 99 get no benefit against laboratory confirmed influenza (1 of 100 people vaccinated has no flu). 2 of 100 unvaccinated people has flu. The infection rate in adults drops with the vaccine from 2% per year to 1%. You could say that’s halved, but it effectively only drops by 1%.
(4) Influenza vaccine does not prevent flu complications neither flu mortality.
(5) In the US, they have been carrying a three-decades history of influenza vaccination, and 150 million Americans are currently vaccinated each year, with no effect on flu mortality. See the figure in:
(6) Influenza vaccine does not produce herd inmunity, does not avoid transmission from professionals to patients or grandparents to grandchildren or professors to students. There is little evidence on prevention of complications, transmission, or time off work.
(7) Influenza vaccine is associated with more virus aerosol generation in vaccinated people with flu; 6.3 times more aerosol shedding among cases with vaccination in the current and previous season compared with having no vaccination in those two seasons.
(8) Minor infuenza adverse effects are common; there are uncommon severe adverse effects as thrombocytopenia, lymphadenopathy, anaphylaxis, other allergic/hypersensitivity reactions (including urticaria, angioedema), Guillain-Barré syndrome (GBS), convulsions, febrile convulsions, myelitis (including encephalomyelitis and transverse myelitis), facial palsy (Bell’s palsy), optic neuritis/neuropathy, brachial neuritis, syncope (shortly after vaccination), dizziness, paresthesia, vasculitis, vasodilatation/flushing, dyspnea, pharyngitis, rhinitis, cough, wheezing, throat tightness, Stevens-Johnson syndrome, etc.
(9) When vaccinated against influenza from the previous season, the probability of spontaneous abortion among pregnant women who receive an A H1N1 vaccine almost multiplies by 8 (7.7 – 95% CI: 2.2 -27.3) within 29 days of vaccination. The same probability for pregnant women who are not vaccinated against seasonal influenza is 1.3 (95% CI 0.7-2.7). This change in the effect of the vaccine was observed in each season.
(10) In Europe, pandemic influenza vaccine produce an epidemic of narcolepsy, with more impact in the teenagers population of the Nordic countries.
(11) It is a scientific failure of industry and governments not to address the most important clinical outcomes of influenza vaccination for patients and professionals.
By Juan Gérvas, MD, PhD
Note: The information is according to the science; see the references. But this summary is from the author and does not represent the position of the Vaccines Committee of the Spanish Association of Public Health (JG is a member of this Committee), neither of the National School of Public Health (JG is a visiting professor).