Measles Infection and Immune Amnesia
Yes, measles infection causes profound and prolonged immune suppression that significantly decreases protection against other diseases, a phenomenon known as "immune amnesia" that can persist for months to years after recovery. 1, 2, 3
Mechanism of Immune System Damage
Measles virus directly infects and depletes immune cells through several mechanisms:
Lymphocyte depletion occurs during acute infection, with measles virus using CD150 as a receptor to infect both B and T cells in lymphoid tissue, which is a primary site of viral replication. 3
Pre-existing antibody diversity is reduced following measles infection, with documented decreases in numbers of memory and naive B cells that provide protection against other pathogens. 3
Immune suppression persists for months after clinical recovery, creating a prolonged window of vulnerability to secondary bacterial and viral infections. 4, 5
Clinical Consequences of Immune Amnesia
The immunosuppressive effects translate directly into increased morbidity and mortality:
Deaths from measles are primarily due to secondary infections rather than the virus itself, attributed to the prolonged state of immune suppression that follows infection. 5
Susceptibility to other infections is markedly increased during and after measles, with documented loss of immunity to previously encountered pathogens. 2, 3
Mortality rates reach 1-2 per 1,000 cases in the United States, with substantially higher rates (up to 25%) in developing countries, largely driven by secondary infections enabled by immune suppression. 1
Specific Immune Abnormalities
Multiple immune system components are affected:
Lymphocyte number and function are altered, with shifts in cytokine responses including down-regulation of interleukin-12 and immunomodulatory effects of interleukin-10. 5
Antigen presentation is impaired, with interference in the maturation and function of professional antigen-presenting cells like dendritic cells. 4
Interferon alpha/beta signaling pathways are disrupted, contributing to the inability to mount effective responses against other pathogens. 5
High-Risk Populations
Certain groups face particularly severe consequences:
Immunocompromised persons can experience severe, prolonged measles without typical rash and may shed virus for weeks, with documented deaths from vaccine-associated measles infection in severely immunocompromised individuals. 6, 1
Infants under 12 months are at highest risk for severe disease and complications, yet are too young for routine vaccination. 1
Pregnant women have increased rates of premature labor, spontaneous abortion, and low birth weight infants when infected with measles. 1
Prevention Is Critical
The immune amnesia phenomenon makes prevention through vaccination essential:
Measles vaccine induces long-term immunity in approximately 95% of children vaccinated at 12 months and 98% at 15 months, without causing the immune suppression associated with natural infection. 6, 7
Two-dose vaccination schedules achieve >99% immunity when the first dose is given after the first birthday, providing protection without the devastating immune consequences of natural infection. 6
Vaccination prevents not only measles but also the subsequent immune amnesia, protecting against both the acute disease and the prolonged vulnerability to other infections that follows natural measles infection. 1, 2
Common Pitfall to Avoid
Do not assume that "natural immunity" from measles infection is superior to vaccine-induced immunity—while natural infection does produce lifelong measles immunity, it comes at the cost of profound immune suppression and loss of protection against other diseases, whereas vaccination provides comparable measles immunity without these devastating immunologic consequences. 2, 5, 3