Diphtheria Toxoid Vaccine

The diphtheria toxoid vaccine, developed in 1923, was a major breakthrough in the prevention of diphtheria, a potentially deadly bacterial infection caused by Corynebacterium diphtheriae.

Key Milestone: 1923 – Diphtheria Toxoid Vaccine Developed

Developer(s):

  • Gaston Ramon (France)

  • Alexander Thomas Glenny (UK)

These researchers worked independently but reached similar conclusions around the same time.

What Is a Toxoid Vaccine?

A toxoid vaccine is made by inactivating a bacterial toxin (in this case, diphtheria toxin) so that it cannot cause disease but still triggers an immune response.

  • The toxin is treated with formaldehyde, rendering it harmless.

  • The inactivated toxin (toxoid) still resembles the real toxin enough to provoke the immune system to produce antibodies.

  • This way, the body learns to fight the real diphtheria toxin if exposed in the future.

Scientific Development:

Gaston Ramon (Pasteur Institute, France):

  • Used formalin (a solution of formaldehyde in water) to detoxify the diphtheria toxin.

  • Discovered that mixing the toxoid with adjuvants (e.g., aluminum salts) enhanced the immune response.

  • Published early results demonstrating protective effects in animals.

Alexander T. Glenny and colleagues (Wellcome Research Laboratories, UK):

  • Coined the term “toxoid.”

  • Independently confirmed that formaldehyde could detoxify diphtheria toxin.

  • Conducted human trials and helped standardize the production process.

Impact:

  • Mass immunization campaigns using the toxoid vaccine began in the 1930s.

  • It drastically reduced diphtheria incidence and mortality in developed countries.

  • Became a key part of the DTP vaccine (Diphtheria, Tetanus, Pertussis) introduced later.

Results:

  • Before vaccination: Diphtheria caused tens of thousands of deaths annually, especially among children.

  • After widespread immunization: Near eradication in many regions.

Legacy:

The 1923 diphtheria toxoid vaccine marked a turning point in toxin-based vaccine development, paving the way for:

  • Tetanus toxoid (developed in the 1920s–30s)

  • Combination vaccines (like DTP in the 1940s–50s)