We were recently contacted regarding the testing for antibodies (immunity) against measles as part of a pre-employment physical. This is a common request for jobs in health care and for some colleges.
Why would antibodies be low even though immunizations were given in childhood?
Immunity may wane over time – i.e., we are no longer immune to the illness that we were immunized against. Sometimes there is still immunity but not enough antibodies to be measured to be positive on the blood test.
The development of infections in populations previously immunized is a public health matter that is monitored by our public health system. When it is noted, a change in recommendations is made. For example, it has been noted that whooping cough (pertussis) is making a comeback in adults who were previously immunized. Therefore, it is recommended that as adults become due for their next diphtheria-tetanus shot (dT) (that is recommended every 10 years) that we get a dTaP (diphtheria-tetanus-pertussis) shot this time.
In the health care world, employers are very careful with measles and rubella (German measles) immunity (and others) in their employees because of serious implications for patients who might develop these diseases if exposed to a health care worker who gets the disease (due to lack of immunity).
Is this typical in adults with Down syndrome?
Although it is not something we routinely test for, theoretically loss of immunity in adults with DS is something that might occur more frequently because immune dysfunction is more common in people with DS. However, we have not seen a case of measles in our patients nor am I aware of any data indicating that it occurs with a high enough frequency to warrant a different recommendation that would include routine testing or re-immunization in otherwise healthy adults with DS.
Health care employers
A health care employer may recommend a 2-shot series of MMR (Measles-Mumps-Rubella). A 2-shot series for a health care worker who is not immune is the standard recommendation. There is no reason that I am aware of that an otherwise healthy adult with DS should not get the MMRs.
The Centers for Disease Control and Prevention (CDC) has a helpful question and answer page for the MMR vaccination.
Were there any changes in the recommendation for measles immunizations for adults during the recent increase in measles infections?
The CDC did not change the recommendations. They did not recommend additional vaccinations (for most people) if there is evidence of immunity.
How does the CDC define evidence of immunity?
Acceptable presumptive evidence of immunity against measles includes at least one of the following:
- Written documentation of adequate vaccination:
- One or more doses of a measles-containing vaccine administered on or after the first birthday for preschool-age children and adults not at high risk
- Two doses of measles-containing vaccine for school-age children and adults at high risk, including college students, healthcare personnel, and international travelers
- Laboratory evidence of immunity (blood test)
- Laboratory confirmation of measles illness (blood test)
- Birth before 1957
Additional information is available on the CDC website.
It looks like some groups do not fit the standard recommendations above.
That is correct! For those in the following groups, a second dose is recommended (if only one dose was received) and/or blood tests are recommended to demonstrate immunity:
- Students at post-high school education institutions
- Healthcare personnel
- International travelers
- People who public health authorities determine are at increased risk during an outbreak