极少的健康问题是由疫苗引起的

An analysis of more than 1,000 research articles concluded that few health problems are caused by or clearly associated with vaccines. A committee of experts convened by the Institute of Medicine to review the scientific literature on possible adverse effects（不良反应） of vaccines found convincing evidence of 14 health outcomes -- including seizures, inflammation of the brain, and fainting -- that can be caused by certain vaccines, although these outcomes occur rarely. It also found indicative though less clear data on associations between specific vaccines and four other effects, such as allergic reactions and temporary joint pain. In addition, the evidence shows there are no links between immunization and some serious conditions that have raised concerns, including Type 1 diabetes and autism. The data were inadequate to reach conclusions about other suggested adverse effects.

The review will help the U.S. Department of Health and Human Services (HHS) administer the Vaccine Injury Compensation Program (VICP). VICP is committed to using science-based evidence to inform its decisions about vaccine-related adverse effects, and HHS turned to IOM to provide a comprehensive review of study results on eight vaccines covered by the program. The report's findings will be useful to all stakeholders（利益相关者） involved in vaccine compensation decisions, including VICP staff, people filing claims, special masters that rule on vaccine cases, and others.

Convincing evidence shows that the measles-mumps-rubella (MMR麻疹、腮腺炎和风疹的混合疫苗) vaccine can lead to fever-triggered seizures in some individuals, although these effects are almost always without long-term consequences, the report says. The MMR vaccine also can produce a rare form of brain inflammation in some people with severe immune system deficiencies. In a minority of patients, the varicella（水痘） vaccine against chickenpox can induce brain swelling, pneumonia, hepatitis（肝炎） , meningitis, shingles, and chickenpox in immunocompromised patients as well as some who apparently have competent immune function, the committee found. The majority of these problems have occurred in individuals with immunodeficiencies, which increase individuals' susceptibility to the live viruses used in MMR and varicella. Six vaccines -- MMR, varicella, influenza, hepatitis B, meningococcal, and the tetanus-containing vaccines -- can trigger anaphylaxis（过敏性反应） , an allergic reaction that appears shortly after injection. And, in general, the injection of vaccines can trigger fainting and inflammation of the shoulder, the committee noted.

The evidence suggests that certain vaccines can lead to four other adverse effects, although the data on these links are not as convincing, the report says. The MMR vaccine appears to trigger short-term joint pain in some women and children. Some people can experience anaphylaxis after receiving the HPV vaccine. And certain influenza vaccines used abroad have resulted in a mild, temporary oculo-respiratory（呼吸的） syndrome characterized by conjunctivitis, facial swelling, and mild respiratory symptoms.