Can a 45-year-old man acquire measles if he is not immune?

Can a 45-Year-Old Male Get Measles?

Yes, a 45-year-old man can absolutely acquire measles if he is not immune, and adults born in 1957 or later (which includes this patient) are specifically at risk and require vaccination if they lack evidence of immunity. 1, 2

Understanding Immunity Status by Birth Year

The key determinant is birth year relative to 1957:

• Adults born before 1957 are generally considered immune to measles because they likely had natural infection during childhood when measles was endemic 1, 2
• Adults born in 1957 or later (including your 45-year-old patient born around 1980) should NOT be presumed immune and need documentation of immunity 1, 2

However, this birth year cutoff is not absolute. Research shows that 4.5% of healthcare workers over 40 years old tested seronegative for measles, with 26% of seronegative individuals being over 40 3. Additionally, 29% of healthcare workers who developed measles between 1985-1989 were born before 1957 4.

Evidence of Immunity Required

For adults born in 1957 or later, acceptable evidence of immunity includes 1, 2:

1. Documentation of 2 doses of MMR vaccine (given at least 28 days apart after first birthday)
2. Laboratory evidence of immunity (positive IgG serology)
3. Laboratory confirmation of previous measles disease
4. NOT physician-diagnosed measles (this is insufficient)

Clinical Reality in Adults

Adults can and do get measles, often with comparable or more severe disease than children:

• Adult measles patients show similar clinical signs to pediatric cases but may have slightly more severe presentations 5
• Complications occurred in 15% (17/113) of adult inpatients in one study, including encephalitis and pneumonia 5
• Case reports document measles in vaccinated adults, including a 23-year-old with 2 prior MMR vaccinations 6
• Adults aged ≥20 years accounted for 22% of measles cases in 1989-1990, with 67% inadequately vaccinated 4

Vaccination Recommendations for This Patient

If this 45-year-old lacks documentation of immunity, he should receive:

• At least 1 dose of MMR vaccine as baseline protection 1, 2
• 2 doses of MMR vaccine (minimum 28 days apart) if he is:
  • A healthcare worker 1, 2
  • Planning international travel 1, 2
  • A student in postsecondary education 1
  • In an outbreak setting 2

Common Pitfalls to Avoid

1. Do not assume immunity based on age alone - even adults over 40 may be susceptible 3
2. Do not accept physician-diagnosed measles as evidence of immunity - only laboratory confirmation counts 1, 2
3. Do not rely on vaccination history from 1963-1967 - killed measles vaccine recipients need revaccination with 2 doses of MMR 1, 4
4. Do not assume one dose is sufficient - high-risk adults need 2 doses for optimal protection 1, 4

Bottom Line

A 45-year-old man born around 1980 is definitively in the at-risk category for measles acquisition. Without documented immunity, he requires MMR vaccination - either 1 or 2 doses depending on his occupation and risk factors. The presumption of immunity applies only to those born before 1957, and even then, healthcare workers should be considered for vaccination if susceptibility is suspected.