Diagnostics for resurging vaccine-preventable diseases

EUROIMMUN offers an extensive portfolio of serological assays for detection of IgG and IgM antibodies against pathogens of vaccine-preventable diseases, as well as PCR-based assays for direct detection of selected parameters. The tests support diagnosis of acute cases and for some parameters, determination of individual immune status and epidemiological surveillance

Resurgence of vaccine-preventable diseases (VPD)

Declining rates of vaccination are causing a resurgence of some serious vaccine-preventable diseases (VPD). Measles and whooping cough are of particular concern due to their significant morbidity and mortality, especially in infants and young children.

Measles is a highly contagious airborne disease, which can lead to severe complications, such as pneumonia and encephalitis, and even death. A vaccination coverage of around 95% is required to achieve and maintain herd immunity. However, only 83% of children globally received their first vaccine dose in 2023, a decline from 86% in 2019 according to the WHO¹. There were an estimated 10.3 million cases of measles worldwide in 2023 and 107,500 deaths, mostly in unvaccinated or under-vaccinated children under 5 years old². Recently, the European region reported the highest number of measles cases in 25 years, amounting to 127,350 cases in 2024³.

Whooping cough, caused by the bacterium Bordetella pertussis, has seen a similar resurgence. Globally, the WHO reported 163,000 cases in 2023, up from 64,000 in 2022⁴. The disease is highly contagious and poses a high risk for infants under 1 year old. Pneumonia is a common complication of the infection⁵.

Further examples of infectious diseases for which there are effective vaccines include mumps, rubella, varicella, diphtheria and tetanus. Reduced vaccine coverage has also been reported for these diseases. For example, in the US, coverage in children has declined to less than 93% for all reported vaccines. Accumulation of clusters of under-vaccinated children in some states poses an increased risk of disease outbreaks⁶.

Laboratory diagnostics

Diagnosis of acute cases of VPD is typically based on clinical examination and laboratory testing. The main laboratory methods are PCR-based direct pathogen detection and serological detection of specific IgM antibodies and/or a significant titer increase in IgG antibodies. In acute infections of the central nervous system (CNS) such as encephalitis or meningitis, which can be medical emergencies, investigation of specific IgG antibodies in the cerebrospinal fluid (CSF) can support the diagnosis.

Individual immune status is established by serological measurement of specific IgG antibodies, which are quantified in relation to international reference sera. If no reference material exists, for example for mumps virus, serological IgG detection can help to assess previous exposure to the pathogen or vaccine.

Extensive range of serological assays

EUROIMMUN (part of Revvity) offers a comprehensive range of ELISAs and chemiluminescence immunoassays (ChLIA) for detection of IgG and IgM antibodies against agents of VPD in serum or plasma. The parameters include globally relevant VPD such as measles, mumps, rubella, varicella, pertussis, diphtheria and tetanus, as well as parameters that are important for regional vaccinations, for example tick-borne encephalitis (TBE), dengue, or Japanese encephalitis.

Special ELISA formats for use with CSF are also available to support diagnosis of CNS infections caused by neurotropic VPD pathogens such as mumps, measles, rubella, varicella zoster and TBE viruses.

EUROIMMUN assays are based on carefully selected antigens for optimal performance in each application. For example, use of recombinant proteins for detection of IgM against measles, rubella and varicella zoster virus (VZV) ensures high specificity.

For detection of IgG antibodies, viral lysates provide high sensitivity. Inclusion of antigens from vaccinations strains, for example for mumps virus, helps to boost the serological detection rate in vaccinated individuals.

Assays for detection of antibodies against Bordetella pertussis are based on specific pertussis toxin, which enables simultaneous exclusion of B. parapertussis infection. All serological assays can be fully automated for increased standardization and efficiency. EUROIMMUN offers a range of automation systems catering to different throughput requirements.

Analysis using dried blood spots

A novel feature of the Anti-Measles Virus ELISA 2.0 (IgG) is the option to use dried blood spots (DBS) as sample material as an alternative to venous blood. Diagnostics using DBS require only droplets of capillary blood to provide a reliable result. Samples are typically taken from the fingertip and deposited onto a paper card, which can then be sent to a diagnostic laboratory for analysis.

Due to the minimally invasive sampling method and high sample stability, diagnostics using DBS are beneficial in routine testing, for use in studies or in regions without developed medical infrastructure. Further ELISAs for use with DBS are in development.

Real-time PCR assays

EUROIMMUN’s serology range is complemented by selected assays for direct pathogen detection. A EURORealTime assay for detection of respiratory syncytial virus (RSV) including differentiation of the viral types A and B has recently been introduced. Vaccination or immunisation to RSV is now recommended in many countries for older persons, pregnant women and infants.

EUROIMMUN also offers PCR kits manufactured by GeneProof (part of NuvinkaDx), for example for the detection of VZV or for detection and differentiation of B. pertussis and B. parapertussis in a single reaction.

Summary

• Some vaccine-preventable diseases such as measles and pertussis are resurging due to declining vaccination rates
• Laboratory tests can aid acute diagnostics and immune status determination
• EUROIMMUN offers an extensive range of serological tests for VPD, as well as RT-PCR assays
• Use of dried blood spots for detection of anti-measles virus antibodies increases the ease and convenience of testing

References

1. WHO: Measles – retrieved May 15, 2025 from www.who.int/news-room/fact-sheets/detail/measles

2. WHO: Measles cases surge worldwide, infecting 10.3 million people in 2023 – retrieved May 15, 2025 from www.who.int/news/item/14-11-2024-measles-cases-surge-worldwide--infecting-10.3-million-people-in-2023

3. WHO: Highest number of measles cases in more than 25 years – retrieved May 15, 2025 (www.who.int/europe/news/item/13-03-2025-european-region-reports-highest-number-of-measles-cases-in-more-than-25-years---unicef--who-europe)

4. WHO Immunization Data Global – retrieved May 15, 2025 from https://immunizationdata.who.int

5. WHO: Pertussis – retrieved May 15, 2025 from www.who.int/health-topics/pertussis

6. CDC: Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten — United States, 2023–24 School Year – retrieved May 15, 2025 from www.cdc.gov/mmwr/volumes/73/wr/mm7341a3.htm

More information on EUROIMMUN Infection Diagnostics can be found at www.euroimmun.com/products/infection-diagnostics

Regulatory status, precise intended use and product availability must be verified for the user‘s individual jurisdiction.