A review by the
U.S. National Institutes of Health (NIH) concluded that the 2009 H1N1 ("swine flu") vaccine has a safety profile similar to that of seasonal vaccine. In this study no patients reported serious adverse events, with the most commonly observed events being pain at the injection site and fever, which occurred in 10–25% of people. , the World Health Organization (WHO) said that 65 million doses of vaccine had been administered and that it had a similar safety profile to the seasonal flu vaccine, with no significant differences in the adverse events produced by the different types of vaccine. There has been one report of an adverse event per 10,000 doses of vaccine, with only five percent of these adverse events being serious, an overall rate of serious events of one in 200,000 doses. In Japan, around 15 million people had been vaccinated by 31 December 2009. 1,900 cases of side effects and 104 cases of death were reported from medical institutions. The health ministry announced that it will conduct epidemiologic investigation. In France, around five million people had been vaccinated by 30 December 2009. 2,657 cases of side effects, eight cases of intrauterine death and five cases of miscarriages were reported after vaccination by
afssaps. Rare potential adverse events are temporary bleeding disorders and
Guillain–Barré syndrome (GBS), a serious condition involving the
peripheral nervous system, from which most patients recover fully within a few months to a year. Some studies have indicated that influenza-like illness is itself associated with an increased risk of GBS, suggesting that vaccination might indirectly protect against the disorder by protecting against flu. Some scientists have reported concerns about the longer-term effects of the vaccine. For instance,
Sucharit Bhakdi, professor of medical microbiology at the Johannes Gutenberg University of Mainz in Germany, wrote in the journal,
Medical Microbiology and Immunology, of the possibility that immune stimulation by vaccines or any other cause might worsen pre-existing heart disease. Chris Shaw, a neuroscientist at the University of British Columbia, expressed concern that serious side-effects may not appear immediately; he said it took five to ten years to see most of the
Gulf War syndrome outcomes. Although one review gives an incidence of about one case per million vaccinations, a large study in China, reported in
The New England Journal of Medicine covering close to 100 million doses of H1N1 flu vaccine found only eleven cases of
Guillain–Barré syndrome, A 2004 review of the safety of influenza vaccines in children stated that the live vaccine had been shown to be safe but that it might trigger wheezing in some children with asthma; less data for the trivalent inactivated vaccine was available, but no serious symptoms had been seen in clinical trials.
Squalene Newsweek states that "wild rumours" about the swine flu vaccine are being spread through e-mails, it writes that "The claims are nearly pure bunk, with only trace amounts of fact." These rumours generally make unfounded claims that the vaccine is dangerous and they may also promote
conspiracy theories. An adjuvant is a substance that boosts the body's immune response, thereby stretching the supply of the vaccine and helping immunize elderly people with a weak immune system. None of the formulations of vaccine used in the US contain squalene, or any other adjuvant. However, some European and Canadian formulations do contain 25 μg of squalene per dose, which is roughly the amount found in a drop of olive oil. Some animal experiments have suggested that squalene might be linked to autoimmune disorders. although others suggest squalene might protect people against cancer. Squalene-based adjuvants have been used in European influenza vaccines since 1997, with about 22 million doses administered over the past twelve years. The WHO states that no severe side effects have been associated with these vaccines, although they can produce mild inflammation at the site of injection. and one with elderly people, in both trials the vaccine was safe and well tolerated, with only weak side-effects, such as mild pain at the injection site. A 2009
meta-analysis brought together data from 64 clinical trials of influenza vaccines with the squalene-containing adjuvant MF59 and compared them to the effects of vaccines with no adjuvant. The analysis reported that the adjuvanted vaccines were associated with slightly lower risks of chronic diseases, but that neither type of vaccines altered the normal rate of autoimmune diseases; the authors concluded that their data "supports the good safety profile associated with MF59-adjuvanted influenza vaccines and suggests there may be a clinical benefit over non-MF59-containing vaccines". A 2004 review of the effects of adjuvants on mice and humans concluded that "despite numerous case reports on vaccination induced autoimmunity, most epidemiological studies failed to confirm the association and the risk appears to be extremely low or non-existent", although the authors noted that the possibility that adjuvants might cause damaging immune reactions in a few susceptible people has not been completely ruled out. A 2009 review of oil-based adjuvants in influenza vaccines stated that this type of adjuvant "neither stimulates antibodies against squalene oil naturally produced by the humans body nor enhances titers of preexisting antibodies to squalene" and that these formulations did not raise any safety concerns. A paper published in 2000 suggested that squalene might have caused of
Gulf War syndrome by producing anti-squalene antibodies, although other scientists stated that it was uncertain if the methods used were actually capable of detecting these antibodies. A 2009 U.S. Department of Defense study comparing healthy Navy personnel to those suffering from Gulf War syndrome was published in the journal
Vaccine, this used a validated test for these antibodies and found no link between the presence of the antibodies and illness, with about half of both groups having these antibodies and no correlation between symptoms and antibodies. Furthermore, none of the vaccines given to US troops during the Gulf war actually contained any squalene adjuvants.
Thiomersal Multi-dose versions of the vaccine contain the preservative
thiomersal (also known as thimerosal), a
mercury compound that prevents contamination when the vial is used repeatedly. Single-dose versions and the live vaccine do not contain this preservative. (The comparison of the injected and ingested quantities is for reference only, since the rate of absorption of ingested elemental mercury into the bloodstream is less than 0.01%.) In Canada, different variants contain five and 50 micrograms of thimerosal per dose. The use of thiomersal has been
controversial, with claims that it can cause
autism and other
developmental disorders. The U.S.
Institute of Medicine examined these claims and concluded in 2004 that the evidence did not support any link between vaccines and autism. Other reviews came to similar conclusions, with a 2006 review in the
Canadian Journal of Neurological Sciences stating that there is no convincing evidence to support the claim that thimerosal has a causal role in autism, and a 2009 review in the journal
Clinical Infectious Diseases stating that claims that mercury can cause autism are "biologically implausible". The U.K.
National Health Service stated in 2003 that "There is no evidence of long-term adverse effects due to the exposure levels of thiomersal in vaccines." The
World Health Organization concluded that there is "no evidence of toxicity in infants, children or adults exposed to thiomersal in vaccines". In 2008 a review noted that even though thiomersal was removed from all US childhood vaccines in 2001, this has not changed the number of autism diagnoses, which are still increasing.
Dystonia According to the CDC, there is no evidence either for or against
dystonia being caused by the vaccinations. Dystonia is extremely rare. Due to the very low numbers of cases, dystonia is poorly understood. In one discredited case, a woman wrongly blamed difficulties with movement and speech on a seasonal influenza vaccination. The Dystonia Medical Research Foundation stated that it is unlikely that the symptoms in this case were actually dystonia and stated that there has "never been a validated case of dystonia resulting from a flu shot". A
vaccine court special master concluded that the woman's symptoms weren't from the vaccine.
Children vaccine recall On 15 December 2009, one of the five manufacturers supplying the H1N1 vaccine to the United States recalled thousands of doses because they were not as potent as expected. The French manufacturer
Sanofi Pasteur voluntarily recalled about 800,000 doses of vaccine meant for children between the ages of six months and 35 months. The company and the
Centers for Disease Control and Prevention (CDC) emphasized that the recall was not prompted by safety concerns, and that even though the vaccine is not quite as potent as it is supposed to be, children who received it do not need to be immunized again. The CDC emphasized that there is no danger for any child who received the recalled vaccine. When asked what parents should do, CDC spokesman Tom Skinner said, "absolutely nothing." He said if children receive this vaccine, they will be fine.
Narcolepsy in Finland and Sweden In 2010,
The Swedish Medical Products Agency (MPA) and
The Finnish National Institute for Health and Welfare (THL) received reports from Swedish and Finnish health care professionals regarding
narcolepsy as suspected adverse reaction following
Pandemrix flu vaccination. The reports concern children aged 12–16 years where symptoms compatible with
narcolepsy, diagnosed after thorough medical investigation, have occurred one to two months after vaccination. THL concluded in February 2011 that there is a clear connection between the Pandemrix vaccination campaign of 2009 and 2010 and narcolepsy epidemic in Finland: there was a nine times higher probability to get narcolepsy with vaccination than without it. At the end of March 2011, an MPA press release stated: "Results from a Swedish registry based cohort study indicate a 4-fold increased risk of narcolepsy in children and adolescents below the age of 20 vaccinated with Pandemrix, compared to children of the same age that were not vaccinated." The same study found no increased risk in adults who were vaccinated with Pandemrix. ==Availability==