Serología negativa frente a parotiditis en niña sana bien vacunada

No se recomienda hacer estudios serológicos de parotiditis epidémica después de la vacunación con triple vírica.

En el contexto del estudio de un caso sospechoso de parotiditis, en un no vacunado (en caso de parotiditis en persona vacunada la serología no tiene utilidad), sería recomendable hacer serología seriada (falsos negativos de la IgM e IgG en fase aguda) y complementarla con estudios de PCR. Y actuar en función del resultado final. Si IgM e IgG negativas, sin seroconversión en la segunda muestra: vacunar con 2 dosis de vacuna TV.

Fuera del escenario anterior, cuando se hace serología en una persona vacunada, y en lo que a la parotiditis se refiere, en el caso de IgG negativa o incierta en individuos vacunados con 2 dosis de triple vírica, puede elegirse una de estas opciones:

1. Considerar al individuo inmune, teniendo en cuenta que tiene acreditadas 2 dosis de vacuna y considerando que algunos test de serología posvacunación pueden ser poco sensibles.
2. Considerar al individuo susceptible, y proceder a la vacunación con 1 dosis de vacuna TV, teniendo en cuenta que puede tratarse de un fallo vacunal o de un caso de pérdida de la protección mediada por anticuerpos con el tiempo, por la limitada inmunogenicidad de la vacuna, y que la vacunación del individuo ya inmune no constituye un riesgo relevante. Tener en cuenta que esta estrategia puede ser la prefererida especialmente los casos de mayor riesgo: sanitarios, profesionales de centros escolares e instituciones cerradas o semicerradas, convivientes de inmunocomprometidos, y brotes o contexto epidemiológico con incidencia elevada de la enfermedad.

La ACIP deja muy claro que la recomendación de una 3.ª dosis de vacuna, desde el punto de vista de salud pública, SOLO sería aconsejable (con reservas) ante un brote de parotiditis con altas tasas de ataque, en una comunidad con altas coberturas vacunales y para personas que se consideren en particulares situaciones de riesgo, de acuerdo con las autoridades sanitarias.

Un cordial saludo.

Comité Asesor de Vacunas de la AEP

-oOo-

Algunas direcciones de interés sobre este controvertido tema:

http://www.immunize.org/askexperts/nt_mar14.asp
Would you consider a healthcare provider with 2 documented doses of MMR vaccine (Merck) to be immune even if their serology for 1 or more of the antigens comes back negative?
Yes. Healthcare personnel (HCP) with 2 documented doses of MMR vaccine are considered to be immune regardless of the results of a subsequent serologic test for measles, mumps, or rubella.

http://www.immunize.org/askexperts/experts_mmr.asp
We have adult patients in our practice at high risk for measles, including patients going back to college or preparing for international travel, who don't remember ever receiving MMR vaccine or having had measles disease. How should we manage these patients?
You have two options. You can test for immunity or you can just give 2 doses of MMR at least 4 weeks apart. There is no harm in giving MMR vaccine to a person who may already be immune to one or more of the vaccine viruses.
If you or the patient opt for testing, and the tests indicate the patient is not immune to one or more of the vaccine components, give your patient 2 doses of MMR at least 4 weeks apart. If any test results are indeterminate or equivocal, consider your patient nonimmune. ACIP does not recommend serologic testing after vaccination because commercial tests may not be sensitive enough to reliably detect vaccine-induced immunity.

http://www.cdc.gov/vaccines/pubs/surv-manual/chpt09-mumps.html
Healthcare personnel: presumptive evidence of immunity
Results of serum antibody tests in vaccinated persons are difficult to interpret. In vaccinated persons, antibody levels are often lower than following natural infection, and commercially available tests may not detect such low levels of antibody. As a result, postvaccination serologic testing to verify an immune response to MMR or its component vaccines is not recommended. There are no data on the effect of additional (greater than two) doses of mumps vaccine on antibody levels or protection from disease.

http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Conte...
Serological testing for immunity to mumps
Serological testing for immunity to mumps (and measles, rubella and varicella) is not recommended before or after routine administration of the 2-dose childhood schedule of these vaccines.
However, serological testing for mumps (and measles and rubella) can be performed in cases where a history of natural immunity or 2 doses of vaccine administration is uncertain (see ‘Adults and adolescents’ above).
Serology is indicated in special situations, such as pre-pregnancy planning (see also 4.9 Measles, 4.18 Rubella and 4.22 Varicella).
Serological tests to investigate immunity to mumps are generally sensitive at detecting antibody produced by both prior natural infection and vaccination, although sensitivity varies by assay and the clinical setting (e.g. time since vaccination).4 Interpretation of the results of serological testing may be enhanced by discussion with the laboratory that performed the test, ensuring that relevant clinical information is provided. An alternative to serological testing is presumptive administration of MMR vaccine dose(s). There is no known increase in adverse events from vaccinating those with pre-existing immunity to one or more of the vaccine components (see 4.11.11 Adverse events below).