No vaccine and autism link, even in kids with risk factors for autism – Expert Reaction

Danish researchers have found further evidence the measles, mumps, and rubella (MMR) vaccination does not increase the risk for autism. 

The new study also shows the vaccine does not trigger or increase the risk of autism in children who are more susceptible to the developmental disorder, including those whose siblings have autism.

The nationwide study looked at all Danish children born between 1999 and 2010; more than half a million in total. There was also no clustering of autism cases following vaccination.

An accompanying editorial suggests this additional evidence won’t be enough to convince some, and that doctors should use an approach to misinformation which was developed by Australian experts in the ‘Debunking Handbook’.

The SMC asked experts to comment on the study, more details about the study are available on Scimex for registered journalists. 

Dr Helen Petousis-Harris, Senior Lecturer, Vaccinology, University of Auckland, comments:

“The now long since retracted article that proposed the MMR vaccine caused autism based on the purported claims of eight parents has continued to generate scares more than 20-years later. Since that time high-quality research from multiple quarters quickly confirmed there was absolutely no association between the vaccine and autism, the nails went in the coffin one after another in fairly quick succession with a 2014 meta-analysis (that pools together several studies into an even bigger study) concluding no association. Five of those studies included involved 1,256,407 children. More recent studies continue to reinforce the safety of the vaccine.

“We know through modern technologies such as brain imaging and genomics that autism begins long before birth. It is well established that autism has a complex genetic component with many genes implicated in playing a role. Autism is more likely in siblings. Whether or not this predisposed a subgroup of kids to autism after MMR vaccine was first investigated in the US and the findings published in 2015. In that study 95,727 children who had older siblings were assessed for vaccine status and a diagnosis of autistic spectrum disorder. The study concluded three things. One, that receipt of the MMR vaccine was not associated with an increased risk of ASD and two, this was regardless of whether or not a sibling had autism. In other words there was no association, even among kids at higher risk. The third conclusion is that parents with an autistic kid were less likely to vaccinated subsequent children – leaving them more susceptible to disease.

“This most recent study goes even further and includes over half a million children. The message is loud and clear. There is no difference in the risk of autism between vaccinated and unvaccinated kids – even for kids with a higher risk for developing autism.

“I think this reasonably puts to bed the notion that MMR might trigger autism in susceptible subgroups of children. The coffin is both nailed and superglued shut then hermetically sealed.”

Conflict of interest statement: Helen has served on industry expert advisory groups and has received research grants from industry. She does not have any personal financial interests or receive honorarium from industry. None have been related to MMR vaccine.

Professor Michael Baker, University of Otago, Wellington, comments:

“This high quality Danish study is very reassuring for anyone concerned about a possible link between MMR vaccine and autism.  This was a large study that followed all children born in Denmark to Danish-born mothers between 1999 through 2010 (657,461 children) and used a population registry to identify any subsequently diagnosed with autism. Comparing MMR-vaccinated with MMR-unvaccinated children it found no increased risk of autism in the vaccinated group.

“These results should help to reassure parents that MMR vaccine is extremely safe to use.  This is yet another piece of evidence to counter the sad legacy of the Wakefield study published more than 20 years ago in 1998. It raised a potential link between MMR vaccine and autism but has now been discredited and withdrawn by the journal that published it. The misplaced concern it created lowered MMR vaccine use, resulting in measles increases in several countries. This kind of ‘vaccine hesitancy’ has been identified by the World Health Organisation as a major threat to global public health.

“It is important that parents vaccine their children with MMR to protect them from measles, mumps and rubella.  High vaccine coverage also stops these viral diseases from circulating, which is particularly important for measles because it is so infectious.

“New Zealand achieved measles elimination in 2017 meaning that our vaccine coverage was sufficiently high to prevent sustained measles circulation. We are among a growing number of countries that have attained this status, contributing to the ultimate goal of global measles eradication. Although NZ continues to see cases of measles, including an increase in the first two months of this year, these cases are all linked to imported cases in travellers.

“It is important that New Zealanders travelling overseas check their MMR status, particularly teenagers and young adults who may not have received the recommended two doses of MMR vaccine.  Such vaccination will protect them and also reduce their chance of bringing measles back into New Zealand when they return.”

Conflict of interest statement: I am a member of the World Health Organization Regional Verification Commission for Measles and Rubella Elimination.

Nikki Turner, Director of the Immunisation Advisory Centre (IMAC) and Associate Professor in the Division of General Practice and Primary Health Care, University of Auckland, comments on the current measles outbreaks in New Zealand:

“There has been a flurry of news reporting increasing measles outbreaks both internationally and locally. What is going on? The science behind measles control is really clear: If you have high enough immunisation rates you eliminate measles. Measles is a nasty disease with a highly effective remedy, the science is straightforward.

“So, why can’t we eradicate measles? There is a lot of international commentary on the damage from ‘vaccine hesitancy’ (fear and mistrust leading to declining vaccines). Some, but not all, European countries are finding growing anti-immunisation sentiment, magnified by ‘fake news’ in social media. Vaccine hesitancy arises from lack of trust – we have a world where currently there is less institutional trust, increasing equity gaps and power-imbalances.

“However, mistrust is only one piece of the puzzle. In New Zealand, we have actually eliminated measles, any new case starts from an import. If it spreads it is because that case is in contact with someone who is not immune.

“Most cases are occurring in young adults who were unaware they were not completely immunised when they were young. This is the legacy of a system that historically was not so effective at offering services, changed schedules often and does not have a national register for those who missed out.

“There was some added effect from some vaccine hesitancy in the 1990s arising from the myth that arose from a mistaken belief in association with childhood autism.

“We need a great deal more attention on how to translate effective science into effective public health service delivery. Public health messages are embedded in institutional trust and these can easily be eroded. Furthermore, we need to build and nurture social trust – requiring a system that offers quality provision and communication.

“Vaccine-preventable disease is a tricky product to sell at times – the absence of disease is forgotten until it reappears. The simple public health message for New Zealanders is: don’t forget to check your immunisation status. If in doubt, it is safe to revaccinate.”

Conflict of interest statement: I chair the World Health Organization SAGE subcommittee for measles and rubella elimination.

Our colleagues at the Australian Science Media Centre also gathered expert comment on the paper.

Dr James Donnelly, Psychologist, Southern Cross University, comments:

“In general, I believe that parents want to do what is best for their children. However, as a paediatric neuropsychology researcher and clinician, and parent and grandparent, I find it essential that we rely on findings of well-designed research such as the article due to appear in the Annals of Internal Medicine about the lack of a vaccine-autism link.

“In a sample of over 500,000 children followed for several years, using data available through the health system, MMR vaccination did not increase the risk for autism, or trigger autism even in those susceptible due to other factors such as family history. The carefully analysed results add to an already long list of studies that debunked faulty ideas about vaccinations.

“This study is another reminder that we need to guard against biases informed by erroneous information when making important decisions about the causes and management of childhood disorders. To ignore these findings would be irresponsible in my opinion and may put children at increased risk as believing dangerous myths instead leads to poor healthcare choices.

“Sadly, there will still be those who cling to conspiracy theories or coincidental evidence that confirms their fears or suspicions.

“The scientific method is not always applied perfectly and not all findings tell the whole story but it is the best tool we have for testing our guesses about how things work.

“Helping parents and the general public become informed consumers of research findings as they advocate for children is a key role for academics and clinicians across all healthcare disciplines.”

No conflict of interest declared.

Professor Ian Fraser AC, Immunologist, University of Queensland, comments: 

“This comprehensive study across an entire population of over half a million children born in Denmark over 10 years definitively confirms the findings of previous studies that there is no association between administration of the MMR vaccine and subsequent development of autism, or of any of the components of the autism disorder spectrum, even in children recognised as at increased familial risk. It should further reassure parents and prospective parents that MMR vaccination is safe.”

No conflict of interest declared. Prof Fraser is one of the co-developers of the HPV vaccine against cervical cancer.

Professor Katie Flanagan, Infectious Diseases Physician and Clinical Professor, University of Tasmania, comments: 

“All studies since the fraudulent paper of Andrew Wakefield published in the Lancet in 1998 have failed to find a link between MMR vaccination and autism. The paper was subsequently withdrawn but the damage had been done. An increase in vaccine hesitancy and refusal since then has been associated with repeated outbreaks of measles in industrialised countries in recent years, including Australia, with cases doubling in Europe in the last year. Since measles is potentially lethal and highly infectious the ideal scenario would be to eradicate it from the world altogether, as was achieved with smallpox through vaccination. However, measles eradication requires more than 95 per cent of people need to be vaccinated which will be hard to achieve while the mythical link between MMR and autism persists.

Hviid and colleagues performed a comprehensive country-wide analysis of more than 600,000 Danish children and greater than 5 million-person years of follow up, finding no evidence of a link between MMR and autism. It is the largest study yet to address this question. Furthermore, there was no link between MMR and autism even in those deemed at high risk of autism. Perhaps it is time to finally lay to rest the false information that MMR causes autism and get on with the important goal of eradicating this deadly disease once and for all.”

No conflict of interest declared.