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Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.
In ancient Rome, many of the richer people in the population had lead-induced gout. The reason for this is unclear. Lead poisoning has also been linked to madness.
IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.
Asthma cases in Americans are about 75% higher today than they were in 1980.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.