A new study from Aarhus University has used a sample of general practitioners in the Central Denmark Region to show that 94 per cent of children in the region – rather than the 88 per cent as previously assumed – have been vaccinated with the much debated MMR vaccine. Administrative errors may lie behind the discrepancy between the figures.

2017.02.07 | Kirsten Olesen

A new study from Aarhus University indicates that the risk of a measles epidemic in Denmark as a result of too few children being vaccinated may be smaller than feared.

Until now, the Danish Health and Medicines Authority has operated with the figure that only 88 per cent of Danish children are vaccinated against measles, mumps and rubella – known as the MMR vaccine. But now a careful review of 1,712 children's medical records from general practitioner practises in the Central Denmark Region shows that the rate of coverage is instead 94 per cent.

"It is very pleasing to see that far more children than assumed appear to be vaccinated, and that things are thereby apparently better healthwise than we thought," says Professor Flemming Bro from the Department of Public Health, Aarhus University, and the Research Unit for General Practice at Aarhus University.

This is because even though an 88 per cent rate of coverage may sound like a lot, it is not high enough in relation to the risk zone that the World Health Organisation (WHO) has established in connection with measles: According to the WHO, to avoid the risk of an actual epidemic, 95 per cent ought to be vaccinated, say the researchers.

"So if the figures we have now shown with our sample of general practitioners in the Central Denmark Region can be taken as evidence of the general situation here in Denmark, then this is very good news. Measles is a serious disease that can lead to complications," says Flemming Bro.

Sample altered the figures

The new study, which has just been published in the Danish Medical Journal, has discovered there is a far higher level of compliance with the vaccination. The study has taken a detailed look at the general practitioners' patient records, while the figures on which the Danish Health and Medicines Authority bases its recommendations, are based on the payments made by the Danish regions to the general practitioners for carrying out the vaccinations.

A total of 246 of the 1,712 children whose data is included in the study are registered in the Central Denmark Region's data as not being vaccinated. But when the researchers asked the doctors to review their patient records, it turned out that only 111 of them had not received the MMR vaccination. In other words, the sample shows that more than half of the children who appear in the central registries as not being vaccinated, are in fact vaccinated. 

The difference may be even greater

"Our study shows that the discrepancy in the figures may occur when an invoice from the general practitioner is rejected by the system for administrative reasons. If the error is not corrected, then neither is the child registered as vaccinated," says medical doctor and research assistant Nanna Holt from the Research Unit for General Practice at Aarhus University.

"We believe that the discrepancy between the figures may be even greater than our study shows. We are aware, for example, that there can be some doubt about the vaccination status of children who have recently arrived in Denmark. Therefore, a vaccinated child can actually be registered as not being vaccinated in the central registries.”

The researchers hope that their study can pave the way for a new procedure, for example using samples from the general practitioners' patient records, which can uncover the actual figures.

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Facts:

• In countries like Denmark with good hospital standards, 1 out of 2,500 - 12,000 cases of measles will lead to a fatality. In developing countries, the mortality rate is between 1 and 5 deaths per 100 cases of measles.
• The most frequent complications are inflammation of the middle ear, pneumonia and inflammation of the brain.

Source: Statens Serum Institut (SSI)   

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Background for the results:

• Registry study combined with review of patient records. Thirty of the Central Denmark Region’s 381 general practitioners were randomly selected and invited to participate in the study. Nineteen general practice’s with a total of 75,383 patients said yes, which corresponds to vaccination data for a total of 1,712 children aged 18-42 months being included in the study. 
• The study was carried out in collaboration with the Central Denmark Region. 
• The study is financed by the Danish College of General Practitioners and the Danish Research Foundation for General Practice. 
• Conflicts of interest: None. 
• Read the article ”Danish MMR vaccination coverage is considerably higher than reported” in Danish Medical Journal  
• See the Danish Health and Medicines Authority's annual report 2015 on the child vaccination programme (in Danish).

 

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Contact:

Professor Flemming Bro
The Research Unit for General Medical Practice, Aarhus University
Aarhus University, Department of Public Health
fbro@ph.au.dk
Mobile: (+45) 6167 0071

Medical Doctor and Research Assistant Nanna Holt
The Research Unit for General Medical Practice, Aarhus University
n.holt@ph.au.dk
Mobile: (+45) 2190 3916