Flu Vaccine Studies
Cochrane Summary: Vaccines to prevent influenza in healthy adults (June 2013)
Over 200 viruses cause influenza and influenza-like illness which produce the same symptoms (fever, headache, aches and pains, cough and runny noses). Without laboratory tests, doctors cannot tell the two illnesses apart. Both last for days and rarely lead to death or serious illness. At best, vaccines might be effective against only influenza A and B, which represent about 10% of all circulating viruses. Each year, the World Health Organization recommends which viral strains should be included in vaccinations for the forthcoming season.
Authors of this review assessed all trials that compared vaccinated people with unvaccinated people. The combined results of these trials showed that under ideal conditions (vaccine completely matching circulating viral configuration) 33 healthy adults need to be vaccinated to avoid one set of influenza symptoms. In average conditions (partially matching vaccine) 100 people need to be vaccinated to avoid one set of influenza symptoms. Vaccine use did not affect the number of people hospitalized or working days lost but caused one case of Guillian-Barré syndrome (a major neurological condition leading to paralysis) for every one million vaccinations. Fifteen of the 36 trials were funded by vaccine companies and four had no funding declaration. Our results may be an optimistic estimate because company-sponsored influenza vaccine trials tend to produce results favorable to their products and some of the evidence comes from trials carried out in ideal viral circulation and matching conditions and because the harms evidence base is limited.
Cochrane Summary: Vaccines to prevent influenza in healthy children (June 2012)
Click here to read abstract here.
Children (< 16 years old) and the elderly (above 65 years old) are the two age groups that appear to have the most complications following an influenza infection. Influenza has a viral origin and often results in an acute respiratory illness affecting the lower or upper parts of the respiratory tract or both. Viruses are mainly of two subtypes (A or B) and spread periodically during the autumn-winter months. However, many other viruses can also cause respiratory tract illnesses.
Diffusion and severity of the disease could be very different during different epidemics. Efforts to contain epidemic diffusion rely mainly on widespread vaccination. Recent policy from several internationally-recognized institutions, recommend immunization of healthy children between 6 and 23 months of age (together with their contacts) as a public health measure.
The review authors found that in children aged from two years, nasal spray vaccines made from weakened influenza viruses were better at preventing illness caused by the influenza virus than injected vaccines made from the killed virus. Neither type was particularly good at preventing ‘flu-like illness’ caused by other types of viruses. In children under the age of two, the efficacy of inactivated vaccine was similar to placebo. It was not possible to analyze the safety of vaccines from the studies due to the lack of standardization in the information given, but very little information was found on the safety of inactivated vaccines, the most commonly used vaccine in young children.
Estimates of Death Associated with Seasonal Influenza
The Centers for Disease Control and Prevention (CDC) released their Estimates of Deaths Associated with Seasonal Influenza in the U.S. from 1976 to 2007 in the August 27th 2010 Weekly Morbidity and Mortality Report (MMWR). CLICK HERE to read report.
The estimates are derived from national death certificate data and are based on estimates of both respiratory and circulatory deaths, not documented cases of the flu. The annual death rate estimates for this time period ranged from 1.4 to 16.7 per 100,000 persons. The wide variation from year to year was related to the particular influenza virus in circulation.
Ninety percent of all influenza associated deaths are among those 65 years and older. The overall estimated death rate for individuals with underlying pneumonia and influenza causes of death was 2.4 per 100,000. with a range of 0.4 to 5.1. Among those < 19 years of age the rate was 0.1 per 100,000. Among individuals >65 the estimated rate was 17 per 100,000.
This report demonstrates the substantial variability in mortality rates based on year, type of circulating virus and age of the individual. The CDC’s annual estimate of 36,155 influenza respiratory and circulatory associated deaths from influenza are based on an earlier study when more severe influenza viruses were prominent.
British Medical Journal on Flu Vaccines
In May 2010 issue of the British Medical Journal (BMJ) news reported the suspension of flu vaccination in children 5 and younger due to a spike in reports of seizures associated with the vaccine.
In August of 2010 the same journal reported that “Australian health authorities failed to respond quickly and appropriately after a spike in febrile convulsions and other adverse events among children given seasonal influenza vaccination”.
Peter J Collignon, Peter Doshi and Tom Jefferson weighed in on the issue in BMJ asking if we should really be surprised about adverse events following influenza immunization in the U.S. Although authorities promote influenza vaccines as being extremely safe, according to the authors, there is now abundant evidence that such optimism is misguided. They go on to state that “vaccine policies must ensure they are doing more good than harm” and that evidence suggests this is not the case with influenza.
In Australia in 2009, during winter when young children (0-4 years) were first hit with the new H1N1 strain, the admission rate for influenza was 57 per 100,000. In the US, CDC says that influenza results in hospitalization for approximately 20 per 100,000 children aged 2 to 5 years , but vaccine-induced febrile convulsions resulting in hospitalization in US young children, likely occurred at a rate of 114 per 100,000 children vaccinated . According to the FDA, a “serious adverse event” is defined as hospitalization that results from a vaccine adverse event. Thus vaccinating young children without risk factors likely caused more serious adverse events than disease from the new “pandemic” itself.
Black SB, Shinefield HR, France EK, Fireman BH, Platt ST, Shay D; Vaccine Safety Datalink Workgroup. Effectiveness of influenza vaccine during pregnancy in preventing hospitalizations and outpatient visits for respiratory illness in pregnant women and their infants. Am J Perinatol. 2004 Aug;21(6):333-9. Download here.
Burbacher TM, Shen DD, Liberato N, Grant KS, Cernichiari E, and Clarkson T. Comparison of blood and brain mercury levels I infant monkeys exposed to methylmercury or vaccines containing thimerosal. Environmental Health Perspectives. 2005;113(8):1015-1021. View abstract.
Dórea JG. Integrating experimental (in vitro and in vivo) neurotoxicity studies of low-dose thimerosal relevant to vaccines. Neurochem Res. 2011 Jun;36(6):927-38. Epub 2011 Feb 25. View abstract.
Eick AA, Uyeki TM, Klimov A, Hall H, Reid R, Santosham M, O’Brien KL. Maternal influenza vaccination and effect on influenza virus infection in young infants. Arch Pediatr Adolesc Med. 2011
Feb;165(2):104-11. View abstract.
Zaman K, Roy E, Arifeen SE, Rahman M, Raqib R, Wilson E, Omer SB, Shahid NS, Breiman RF, Steinhoff MC. Effectiveness of maternal influenza immunization in mothers and infants. N Engl J Med. 2008 Oct 9;359(15):1555-64. View abstract.