Which of the following diseases CANNOT be prevented by vaccination?

The correct answer is Beri beri.

Let us analyze each option carefully to understand why Beri beri is the disease that cannot be prevented by vaccination.

Understanding Vaccination:
Vaccines work by stimulating the immune system to produce antibodies against a specific pathogen — such as a virus or bacterium. This means vaccines are only effective against infectious diseases caused by living microorganisms. They have no role in preventing diseases caused by nutritional deficiencies.

Option 1 — Rabies:
Rabies is caused by the Rabies lyssavirus, a virus transmitted through the bite of an infected animal. A highly effective rabies vaccine exists and is administered both as a pre-exposure prophylaxis (for high-risk individuals) and as a post-exposure prophylaxis (after a potential exposure). ✅ Can be prevented by vaccination.

Option 2 — Beri beri:
Beri beri is caused by a severe deficiency of Vitamin B₁ (Thiamine). It is a nutritional deficiency disease, not an infectious disease. Since no pathogen (virus or bacterium) is involved, there is no target for a vaccine to act upon. The only way to prevent Beri beri is by ensuring an adequate dietary intake of Thiamine-rich foods (such as whole grains, legumes, and nuts) or through supplementation. ❌ Cannot be prevented by vaccination.

Option 3 — Typhoid:
Typhoid fever is caused by the bacterium Salmonella typhi, spread through contaminated food and water. There are licensed typhoid vaccines (such as the Vi polysaccharide vaccine and the Ty21a oral vaccine) that provide significant protection. ✅ Can be prevented by vaccination.

Option 4 — Measles:
Measles is caused by the Measles morbillivirus. The MMR (Measles, Mumps, Rubella) vaccine is one of the most effective and widely administered vaccines in the world, providing long-lasting immunity. ✅ Can be prevented by vaccination.

Summary Table:

Conclusion:
Beri beri is the correct answer because it is a nutritional deficiency disease caused by lack of Vitamin B₁ (Thiamine), not by any infectious pathogen. Since vaccines only work against infectious agents (viruses, bacteria, etc.), vaccination has absolutely no role in preventing Beri beri. It is prevented purely through proper diet and nutrition.