A survey of health care professionals in the U.S. in 2016 found that the vaccines families were most likely to refuse or request on an alternative schedule included vaccines for HPV, influenza, and measles, mumps and rubella (MMR). In 2018, it was found that 48 percent of adults who did not receive the influenza vaccine stated they did so because they did not trust the vaccine and 26 percent felt the flu vaccine was not effective and therefore not worth getting. Some of the most common reasons families give health care professionals for refusing vaccines or requesting alternative schedules include concerns over added ingredients, worry about side effects, and a fear of connection to autism spectrum disorder. The connection between vaccines and autism stems from a now debunked and retracted paper published in 1998. Although extensive research has shown, and scientific consensus states, there is no link between vaccines and autism, misinformation and conspiracy theories continue to be promoted by the anti-vaccination movement. During the 2017-2018 school year in the U.S., around 7.6 percent of kindergartners in Oregon were exempted from receiving vaccinations, the highest percentage of any U.S. state.
It is true that vaccines, like any medication, can cause side effects. However, these side effects are mostly mild, and severe side effects, such as severe allergic reaction, are very rare. The United States has a system that ensures the safety of vaccines and accepts and monitors reports of adverse effects. For example, from 1988 to early 2019, there were 4,816 petitions filed seeking compensation for injury caused by the influenza vaccine and 161 petitions seeking compensation for death. Around 2,789 such cases ended in compensation, while 446 were dismissed. Nevertheless, it is important to note that just because compensation was rewarded, does not mean the vaccine caused the alleged injury, as a vast majority of such cases are the result of negotiated settlements.
Although there has been a rise in the number of people who question the safety and effectiveness of vaccines, most people still recognize their importance. As of 2018, around 90 percent of parents felt it was very or somewhat important to vaccinate their children, while only three percent said it was not at all important. However, the percentage of parents who believed this to be very important has decreased over the last decade. Similarly, there has been a decrease in the percentage of people who strongly believed they had personally benefitted from the development of vaccines over the past 50 years.