The idea that autism is caused by vaccines has recently been revived by Robert F. Kennedy Jr., the presumptive nominee for US Secretary of Health and Human Services, as well as by president-elect Donald Trump. When asked about vaccines at a recent press conference, Trump reportedly said there was “something wrong” with rising autism rates, adding: “We’re going to find out about it.”
From a research perspective, there is little left to discover about vaccines used in long-standing nationwide vaccine programmes, such as diphtheria, tetanus, whooping cough, polio, measles, mumps and rubella. There is strong data from different countries showing that these vaccines do not cause autism or underlie the vast increase in autism diagnosis rates. So why do suspicions that vaccines cause autism remain?
1. Unawareness of evidence
Reliably and accurately communicating research results to the public is difficult. Research results usually stay in small research or clinical communities. Research is rarely accessible and researchers have few incentives to communicate findings outside of their scientific channels.
Popular media is typically superficial and often primarily interested in controversy that generates public attention.
2. Challenges understanding the science
Science is complicated and in medicine there are rarely absolute truths. The public, however, might expect clear consensus or have difficulty grasping the precise nuance of the science and its findings.
Evidence shows that vaccines do not cause autism or are the reason for increasing diagnosis rates. But it is also in the nature of science that it can neither verify nor exclude totally that vaccines contribute to autism in single individuals.