The bifurcated needle is a two pronged, approximately 2.5 inch long piece of steel, designed to hold freeze dried smallpox vaccine

Smallpox vaccine

The smallpox vaccine was the first successful vaccine to be developed. The process of vaccination was discovered by Edward Jenner in 1796, who acted upon his observation that milkmaids who caught the cowpox virus did not catch smallpox...

 between its two prongs. It can administer up to one hundred vaccinations out of just one vial of the freeze dried vaccine. The established method of vaccination entailed that the needle

Hypodermic needle

A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...

 be dipped in the vaccine, and then punctured into a person's upper left arm

Arm

In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...

 fifteen times to create a small circle. The most effective vaccination will result in a small drop of blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 running down the vaccinated arm.

Dr. Benjamin Rubin

Benjamin Rubin

Benjamin Rubin is an American microbiologist, known as the inventor of the bifurcated vaccination needle, which played an important role in the eradication of smallpox. Rubin invented this device by taking the eyelet of a sewing machine needle and grinding it down.-References:*...

 and Gus Chakros invented the bifurcated needle in 1961 as a means by which to deliver a smallpox vaccination. The bifurcated needle was invented as a more efficient and cost effective alternative to the jet injector

Jet injector

A jet injector is a type of medical injecting syringe that uses a high-pressure narrow jet of the injection liquid instead of a hypodermic needle to penetrate the epidermis...

. It was the primary instrument used during the World Health Organization

World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

's smallpox eradication campaign from 1966–1977, which was spear-headed by Dr. D.A. Henderson.