In one West African country, a measles vaccination programme was started while a measles epidemic was occurring. Subsequently, it was discovered that vaccinated children were more likely to survive through childhood than unvaccinated children, even when there were no measles epidemics. The vaccine had provided the children with some defence against other pathogenic infections. Which statement could explain this additional protection?
- AB-lymphocytes produced memory cells which gave the children passive immunity to these infections.
- BMemory cells produced plasma cells which secreted anti-measles antibodies that bound to antigens that closely resembled measles antigens.
- CMemory cells produced plasma cells which secreted anti-measles antibodies that bound to any antigen.
- DT-lymphocytes produced memory cells which gave the children natural immunity against these other infections.