The WHO European Region is experiencing several outbreaks of measles attributed to the decline in vaccination coverage in the peri-pandemic period. Measles, also known as rubeola, is a highly contagious viral infection caused by the measles virus from the Paramyxoviridae family. The disease is most common in children but can affect all age groups. The infection is easily recognizable due to the appearance of a characteristic rash, following a prodromal phase. According to the World Health Organization (WHO), measles has one of the highest estimated reproductive numbers (R0) among infectious diseases, ranging from 12 to 18 [1]. This suggests that each infected person can spread the disease to approximately 12–18 susceptible individuals in an unvaccinated or previously unexposed population, making it a highly contagious infection with a propensity to cause outbreaks.
After exposure to the virus, the disease typically begins with a prodromal phase lasting about 10–14 days. During this phase, individuals may experience symptoms similar to those of a common cold, such as fever, cough, runny nose, and conjunctivitis. Following this phase, a characteristic rash appears, starting on the face and spreading to the rest of the body – so called “head to toe” rash progression. The rash consists of small, red, raised spots that may merge together and may cause localized discomfort and itching. Other symptoms that occur include high fever, malaise, sore throat, and Koplik's spots, small white spots that appear inside the mouth, specifically on the inner lining of the cheeks [2]. Complications such as pneumonia, encephalitis, ear infections, and even death may arise, especially in young children and individuals with weakened or compromised immune systems [1].
1. Resurgence of the virus and outbreaks in 2023–2024
Since the beginning of 2023, the WHO European Region has experienced a concerning resurgence of measles, with over 30,000 cases reported in the first ten months of 2023, marking a more than 30-fold increase compared to the previous year (Fig. 1, Fig. 2). This has prompted the WHO European Regional Office to emphasize the urgent need for vaccination efforts to prevent the further spread of this potentially dangerous disease and protect the population [3]. The impact of the measles resurgence has been severe, leading to nearly 21,000 hospitalizations and five measles-related deaths. Alarmingly, the outbreak has affected individuals of all age groups, with a significant proportion of cases reported among children aged 1–4 years and adults aged 20 and older.
Fig. 1.
Increase in number of reported confirmed cases in January and February 2024 among European countries according to European Centre for Disease Prevention and Control (ECDC) weekly reports. Legend shows the total number of reported confirmed cases in the year 2023. Note that authors remain neutral in regard to territorial disputes.
Fig. 2.
Number of reported confirmed cases in 2023 among remaining WHO European countries according to WHO provisional monthly measles and rubella data. Legend shows the total number of reported confirmed cases. Note that authors remain neutral in regard to territorial disputes.
This rapid resurgence of measles can be largely attributed to a decline in vaccination coverage in the European region during 2020–2022, a period heavily impacted by the COVID-19 pandemic. Disruptions to immunization systems resulted in a substantial number of un- and under-vaccinated children, with reported national coverages for measles-containing vaccines decreasing from 95% in 2019 to 92% in 2022 (Table 1, Table 2). For the first dose coverage, the sharpest decline was noted in Romania and Poland while three countries – Czechia, France, and Slovenia – increased their coverage during COVID-19 pandemic. Six countries including Cyprus, Estonia, Lithuania, the Netherlands, Poland, and Romania had reported first dose coverage to be less than 90% in 2022.
Table 1.
Measles vaccination coverage (first dose, %) among European Union (EU) countries.
| Country | 2019 | 2020 | 2021 | 2022 | Country | 2019 | 2020 | 2021 | 2022 |
|---|---|---|---|---|---|---|---|---|---|
| Austria | 95.0 | 95.0 | 99.0 | 95.0 | Italy | 94.0 | 92.0 | 94.0 | 94.0 |
| Belgium | 96.0 | 96.0 | 96.0 | 96.0 | Latvia | 99.0 | 99.0 | 97.0 | 96.0 |
| Bulgaria | 95.0 | 88.0 | 89.0 | 91.0 | Lithuania | 93.0 | 90.0 | 88.0 | 87.0 |
| Croatia | 93.0 | 91.0 | 89.0 | 90.0 | Luxembourg | 99.0 | 99.0 | 99.0 | 99.0 |
| Cyprus | 86.0 | 86.0 | 86.0 | 86.0 | Malta | 96.0 | 95.0 | 90.0 | 96.0 |
| Czechia | 92.0 | 94.0 | 97.0 | 97.0 | Netherlands | 94.0 | 94.0 | 93.0 | 89.0 |
| Denmark | 96.0 | 94.0 | 95.0 | 95.0 | Norway | 97.0 | 97.0 | 97.0 | 96.0 |
| Estonia | 88.0 | 91.0 | 89.0 | 82.0 | Poland | 93.0 | 80.0 | 71.0 | 71.0 |
| Finland | 96.0 | 95.0 | 93.0 | 94.0 | Portugal | 99.0 | 99.0 | 98.0 | 98.0 |
| France | 92.0 | 94.0 | 94.0 | 94.0 | Romania | 90.0 | 87.0 | 86.0 | 83.0 |
| Germany | 97.0 | 97.0 | 97.0 | 97.0 | Slovakia | 96.0 | 96.0 | 95.0 | 95.0 |
| Greece | 97.0 | 97.0 | 97.0 | 97.0 | Slovenia | 94.0 | 94.0 | 95.0 | 96.0 |
| Hungary | 99.0 | 99.0 | 99.0 | 99.0 | Spain | 98.0 | 96.0 | 95.0 | 96.0 |
| Iceland | 93.0 | 93.0 | 92.0 | 91.0 | Sweden | 97.0 | 97.0 | 97.0 | 92.0 |
| Ireland | 91.0 | 92.0 | 90.0 | 90.0 | EU Average | 94.7 | 93.7 | 93.0 | 92.5 |
∗Data collected from European Centre for Disease Prevention and Control (ECDC) Surveillance Atlas for Infectious Diseases.
∗∗Bold markings indicate a decrease in vaccination coverage in comparison to 2019 (baseline).
Table 2.
Measles vaccination coverage (second dose, %) among European Union (EU) countries.
| Country | 2019 | 2020 | 2021 | 2022 | Country | 2019 | 2020 | 2021 | 2022 |
|---|---|---|---|---|---|---|---|---|---|
| Austria | 86.0 | 88.0 | 97.0 | 94.0 | Italy | 88.0 | 86.0 | 86.0 | 85.0 |
| Belgium | 82.0 | 83.0 | 83.0 | 83.0 | Latvia | 96.0 | 94.0 | 85.0 | 86.0 |
| Bulgaria | 95.0 | 84.0 | 86.0 | 87.0 | Lithuania | 93.0 | 91.0 | 88.0 | 87.0 |
| Croatia | 95.0 | 91.0 | 90.0 | 90.0 | Luxembourg | 90.0 | 90.0 | 90.0 | 90.0 |
| Cyprus | 88.0 | 88.0 | 88.0 | 88.0 | Malta | 95.0 | 99.0 | 93.0 | 95.0 |
| Czechia | 87.0 | 90.0 | 90.0 | 90.0 | Netherlands | 90.0 | 89.0 | 90.0 | 85.0 |
| Denmark | 90.0 | 90.0 | 94.0 | 94.0 | Norway | 95.0 | 95.0 | 95.0 | 94.0 |
| Estonia | 90.0 | 87.0 | 84.0 | 68.0 | Poland | 92.0 | 95.0 | 95.0 | 95.0 |
| Finland | 93.0 | 93.0 | 93.0 | 92.0 | Portugal | 96.0 | 95.0 | 95.0 | 96.0 |
| France | 86.0 | 90.0 | 90.0 | 90.0 | Romania | 76.0 | 75.0 | 75.0 | 71.0 |
| Germany | 93.0 | 93.0 | 93.0 | 93.0 | Slovakia | 98.0 | 98.0 | 96.0 | 96.0 |
| Greece | 83.0 | 83.0 | 83.0 | 83.0 | Slovenia | 94.0 | 91.0 | 91.0 | 92.0 |
| Hungary | 99.0 | 99.0 | 99.0 | 99.0 | Spain | 94.0 | 94.0 | 91.0 | 92.0 |
| Iceland | 94.0 | 93.0 | 10.0 | 80.0 | Sweden | 93.0 | 92.0 | 91.0 | 91.0 |
| Ireland | NR | NR | NR | NR | EU Average | 91.1 | 90.6 | 87.2 | 88.8 |
∗Data collected from European Centre for Disease Prevention and Control (ECDC) Surveillance Atlas for Infectious Diseases. NR = not reported.
∗∗Bold markings indicate a decrease in vaccination coverage in comparison to 2019 (baseline).
In regards with the second dose coverage, six countries – Austria, Belgium, Czechia, Denmark, France, and Poland – reported an increase in % coverage while 16 countries reported a decline in coverage in 2022. The sharpest decline was observed in Estonia, Iceland, Bulgaria, and Latvia. Outside the EU, countries like San Marino, Switzerland, and Uzbekistan improved measles vaccine coverage for both first and second doses (Table 3, Table 4). On the other hand, 14 countries reported a drop in vaccine coverage for both doses. The sharpest declines were noted for Bosnia and Herzegovina, Georgia, Albania, Moldova, and Ukraine.
Table 3.
Measles vaccination coverage (first dose, %) among other WHO Europe countries.
| Country | 2019 | 2020 | 2021 | 2022 | Country | 2019 | 2020 | 2021 | 2022 |
|---|---|---|---|---|---|---|---|---|---|
| Albania | 94.9 | 91.0 | 86.6 | 85.7 | Moldova | 96.9 | 84.3 | 83.2 | 84.2 |
| Andorra | 99.0 | 98.0 | 99.0 | 98.0 | North Macedonia | NR | 62.9 | 70.4 | 70.7 |
| Armenia | 95.0 | 94.4 | 94.2 | 94.7 | Russia | 97.7 | 97.3 | 97.3 | 97.4 |
| Azerbaijan | 97.5 | 82.3 | 93.2 | 92.6 | San Marino | 85.7 | 89.9 | 88.6 | 90.8 |
| Belarus | 98.2 | 97.2 | 97.7 | 98.3 | Serbia | 86.6 | 78.1 | 74.8 | 81.3 |
| Bosnia & Herzegovina | 81.9 | 60.7 | 60.6 | 58.1 | Switzerland | 95.3 | 97.1 | 95.0 | 96.0 |
| Georgia | 100.0 | 90.9 | 90.1 | 90.1 | Tajikistan | 98.0 | 98.1 | 97.3 | 98.1 |
| Israel | NR | 98.8 | 98.8 | NR | Turkiye | 97.0 | 95.0 | 96.1 | 95.2 |
| Kazakhstan | 99.0 | 92.9 | NR | 95.0 | Turkmenistan | 98.8 | 98.3 | 97.4 | 98.3 |
| Kyrgyzstan | 96.1 | 91.7 | 93.4 | 94.5 | Ukraine | 93.2 | 84.9 | 88.5 | 74.1 |
| Monaco | 88.0 | NR | 88.0 | 88.0 | United Kingdom | 91.0 | 91.1 | 90.9 | 89.8 |
| Montenegro | NR | 23.9 | 18.3 | 32.9 | Uzbekistan | 97.5 | 99.8 | 98.8 | 99.6 |
∗Data collected from WHO/United Nations Children's Fund (UNICEF) Joint Reporting Form on Immunization (JRF). NR = not reported.
∗∗Bold markings indicate a decrease in vaccination coverage in comparison to 2019 (baseline).
Table 4.
Measles vaccination coverage (second dose, %) among other WHO Europe countries.
| Country | 2019 | 2020 | 2021 | 2022 | Country | 2019 | 2020 | 2021 | 2022 |
|---|---|---|---|---|---|---|---|---|---|
| Albania | 96.2 | 94.0 | 91.7 | 92.8 | Moldova | 94.8 | 93.3 | 91.6 | 92.6 |
| Andorra | 96.9 | 93.3 | 96.8 | 96.0 | North Macedonia | NR | 68.5 | 80.4 | 89.2 |
| Armenia | 96.0 | 94.4 | 93.8 | 94.2 | Russia | 96.6 | 96.1 | 96.4 | 96.5 |
| Azerbaijan | 96.6 | 78.9 | 89.9 | 90.7 | San Marino | 79.0 | 79.2 | 81.4 | 84.5 |
| Belarus | 98.1 | 98.1 | 97.7 | 98.1 | Serbia | 91.0 | 84.1 | 85.8 | 89.5 |
| Bosnia & Herzegovina | 75.8 | 60.0 | 63.3 | 60.3 | Switzerland | 89.7 | 93.3 | 94.0 | 94.0 |
| Georgia | 97.0 | 77.4 | 81.3 | 78.3 | Tajikistan | 97.0 | NR | 95.6 | 97.1 |
| Israel | NR | 96.0 | 92.8 | NR | Turkiye | 88.1 | 93.0 | 93.0 | 94.4 |
| Kazakhstan | 97.8 | 90.7 | 95.9 | 97.4 | Turkmenistan | 99.3 | 99.5 | 98.4 | 98.7 |
| Kyrgyzstan | 98.5 | 92.6 | 96.9 | 94.5 | Ukraine | 91.7 | 81.9 | 85.9 | 69.1 |
| Monaco | 79.0 | NR | 80.0 | 80.0 | United Kingdom | 87.0 | 87.5 | 87.4 | 86.5 |
| Montenegro | NR | 76.2 | 79.1 | 69.5 | Uzbekistan | 99.0 | 99.6 | 98.8 | 99.6 |
∗Data collected from WHO/United Nations Children's Fund (UNICEF) Joint Reporting Form on Immunization (JRF). NR = not reported.
∗∗Bold markings indicate a decrease in vaccination coverage in comparison to 2019 (baseline).
The resumption of domestic and international travel, coupled with the relaxation of COVID-19-related public health measures, has heightened the risk of disease transmission, particularly in communities with lower vaccination rates (Fig. 3). Even countries that had previously declared measles as eliminated are now vulnerable to outbreaks due to imported cases, emphasizing the need for sustained high vaccination coverage across all communities. Among all WHO regions, the European region had highest vaccine coverage for both doses, closely followed by the Western Pacific region (Table 5).
Fig. 3.
Number of clinically confirmed (CC), epidemiologically linked (Epi), and laboratory confirmed (LC) cases in 2023 among WHO regions according to WHO provisional monthly measles and rubella data. Note that authors remain neutral in regard to territorial disputes. (Data from the American, African, European, and Western Pacific region are incomplete due to non-reporting of data by all member states in these regions).
Table 5.
Measles vaccination coverage (%) among WHO regions.
| WHO Region | First Dose |
Second Dose |
||||||
|---|---|---|---|---|---|---|---|---|
| 2019 | 2020 | 2021 | 2022 | 2019 | 2020 | 2021 | 2022 | |
| Africa | 71.0 | 70.0 | 68.0 | 69.0 | 33.0 | 40.0 | 41.0 | 45.0 |
| Eastern Mediterranean | 83.0 | 83.0 | 82.0 | 83.0 | 76.0 | 77.0 | 77.0 | 78.0 |
| Europe | 96.0 | 94.0 | 94.0 | 93.0 | 92.0 | 91.0 | 92.0 | 91.0 |
| Americas | 87.0 | 85.0 | 85.0 | 84.0 | 73.0 | 72.0 | 75.0 | 76.0 |
| South-East Asia | 94.0 | 88.0 | 86.0 | 92.0 | 83.0 | 80.0 | 78.0 | 85.0 |
| Western Pacific | 95.0 | 94.0 | 90.0 | 92.0 | 93.0 | 93.0 | 91.0 | 91.0 |
∗Data collected from WHO/United Nations Children's Fund (UNICEF) Joint Reporting Form on Immunization (JRF).
∗∗Bold markings indicate a decrease in vaccination coverage in comparison to 2019 (baseline).
2. Public health response
The resurgence of measles is a stark reminder of the importance of vaccination in safeguarding public health. Addressing the resurgence of measles demands a multi-faceted approach. Efforts to identify and rectify immunization disparities within communities are of utmost importance. Tailored immunization strategies and catch-up campaigns are being initiated, supported by collaborative efforts to conduct case investigations, enhance disease surveillance, and implement outbreak response immunization.
The idea of herd immunity, sometimes referred to as population immunity, is the foundation for the significance of attaining high vaccination coverage, specifically 95% or higher. When a sizable portion of a population is immune to a specific infectious disease, it is known as herd immunity. This phenomenon prevents the disease from spreading and shields those who are not immune, such as young children who cannot receive vaccinations or persons with weakened immune systems. Since measles is a highly contagious viral infection, effective prevention of its spread requires a high level of population immunity.
It is generally acknowledged that the 95% vaccination coverage target is the cutoff point needed to develop measles immunity in the population [4]. When immunization rates drop below this level, vulnerable people become more susceptible to infection, and outbreaks can occur, even in communities with high overall vaccination rates. To regain momentum towards measles elimination, it is imperative that countries prioritize achieving and maintaining over 95% coverage with two doses of measles-containing vaccine. This necessitates a comprehensive assessment of immunity gaps and program weaknesses, with immediate action to address these shortcomings.
Post-pandemic vaccine hesitancy has compounded the complex landscape of vaccination programs. In Europe, there has been a large increase in “anti-vaxxers”, those who delay or refuse vaccines for themselves and their families despite availability of vaccines. This vaccine hesitancy is considered to be one of the most important threats to public health [5]. Pre-pandemic outbreaks of measles in Europe were often linked to factors such as religion, ethnicity or belonging to communities who follow an anthroposophical lifestyle [6] and who question the necessity of vaccines and who are often non-compliant with vaccine schedules in school-age children. Post-pandemic vaccine “fatigue” in the general population is palpable and one of the devastating indirect health-effects of the COVID-19 pandemic has been the disruption of childhood vaccination programs.
The recent increase in measles cases in the WHO European Region highlights the crucial role of vaccination in safeguarding public health. Countries must prioritize equal access to immunization and intensify efforts to achieve and maintain high vaccination rates. Targeted approaches to reach minority communities and to reinforce the importance of vaccination in the general population are indicated. Communication campaigns that address post-pandemic “vaccine fatigue” and new thinking on vaccination choices are important for health care professionals and parents and catch-up vaccination campaigns should be widely available in the community. Coordinated and persistent action is necessary to halt the resurgence of measles and progress towards eradicating this preventable and highly contagious infection. Measles Matter!
Contributor Information
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