Measles surveillance in Europe

More than 18,000 cases of measles have been reported to the European Surveillance System for the 12-month period, 1 September 2023 to 31 August 2024.

Of those cases with a known age, 44.5% were under 5 years and 27.9% over 15 years. The highest notification rates were in children under 12 months.

In those with a known age and vaccination status (15,855 cases), 87.1% were unvaccinated. Another 8.2% had just one dose. There were 13 deaths.

Romania reported the highest number of cases (14,347), followed by Italy (897), Belgium (606), Austria (532) and Germany (516).

According to the report, measles vaccination coverage remains suboptimal in several member countries. A sustained coverage of more than 95% for two doses is required to interrupt transmission.

The report may be viewed at ECDC.

Fifty cases of measles have been notified to Australia’s surveillance system for the same period.

The European surveillance report is an important reminder to travellers who might be visiting countries with suboptimal vaccination coverage. While the risk of exposure might be low in Australia and many other countries, it cannot be taken for granted, even in Europe.

Measles is a highly infectious disease. Over 90% of non-immune individuals exposed to the disease will become symptomatic.

The global risk of measles has increased over the last 2 years. All travellers, particularly those born after 1966 should be assessed for their current measles immunisation status. Special attention should be given to infants travelling to high-risk destinations.

Vaccination recommendations

• Infants 6–11 months of age should be considered for at least one dose of measles containing vaccine. Most mothers of today have vaccine immunity rather than natural immunity. This provides protection for a shorter period.
• Preschool children ≥12 months of age should have two doses of MMR vaccine separated by at least 28 days.
• School-age children should have two doses of MMR.
• Adults born in or after 1966 should have two doses of measles-containing vaccine.
• If administered at ≥12 months of age, one dose of measles-containing vaccine or MMR is 95% effective in preventing measles disease and two doses are 99% effective. One dose of measles-containing vaccine or MMR is approximately 85% effective if administered at 9 months of age.

Early waning of maternal antibody is an important concern

Maternal measles antibodies play a very important role in protecting infants from an early bout of measles.  This transfer may not be achieved in premature infants and early measles protection must be considered if the child is at risk.

The level of protection is also influenced by maternal immunity.  This immunity may be different in mothers with natural immunity and those with vaccine immunity. In a longitudinal study of 221 infants and their mothers in Belgium, only 29% of the infants born to a vaccinated group were considered protected at 3 months compared to 60% in the naturally immune group.  By 6 months, only 1 out of 31 had protective levels versus 10 out of 41 for the naturally immune group.  Neither group showed immunity at 9 months. This study can be sourced at The BMJ.

It should be noted that mothers with vaccine immunity might receive natural boosting in countries where measles transmission persists.  In those countries where transmission has been interrupted (Australia) natural boosting doesn’t occur.

Vaccination of infants over 6 months must be a consideration when travelling overseas.