World Immunization Week 2022 | From Smallpox To Covid-19: How Vaccines Saved Lives For Centuries

Vaccines have helped keep people healthy for more than two centuries, be it the very first vaccine developed to protect against smallpox to the latest vaccine used to prevent severe cases of Covid-19.

Edward Jenner performing his first vaccination on James Phipps

Source : Getty Images

New Delhi: For centuries, humans have searched for ways to protect each other against deadly diseases. Immunisation has a long history, from experiments and taking chances to a global vaccine roll-out in the midst of an unprecedented pandemic. 

Vaccines provide everyone a chance at a fulfilling life, and have helped keep people healthy for more than two centuries, be it the very first vaccine developed to protect against smallpox to the latest vaccine used to prevent severe cases of Covid-19. 

The world has witnessed the unparalleled impact of vaccines on health and well-being, ever since the first vaccine was developed for smallpox in 1796. For centuries, people worldwide have been vaccinated. This led to the eradication of smallpox and driving down of wild polio cases to an all-time low. 

Every year, World Immunization Week is celebrated worldwide in the last week of April, to highlight the importance of vaccines and how immunisation helps protect people from vaccine-preventable diseases. 

Immunisation is one of modern medicine's greatest success stories, and prevents deaths every year in all age groups from diseases like diphtheria, tetanus, pertussis (whooping cough), influenza, and measles. The Centers for Disease Control and Prevention (CDC) engages globally to support the development and implementation of vaccination strategies and programmes that can prevent more than 25 vaccine-preventable diseases. 

Immunisation currently prevents four to five million deaths every year, according to the World Health Organization (WHO). 

From smallpox to Covid-19, here is a story of how vaccines have saved lives for centuries.

Smallpox Vaccine

The basis for vaccination began in the year 1796. English doctor Edward Jenner noticed that milkmaids who contracted cowpox were protected from smallpox, and also knew about variolation, which was one of the first methods for controlling smallpox. Named after variola virus, the causative organism of smallpox, variolation was a process during which people who had never contracted smallpox were exposed to material from smallpox sores called pustules by scratching the material into their arm or inhaling it through the nose. Fewer people died as a result of variolation, compared to the number of deaths that would have occurred if smallpox was acquired naturally.

Jenner guessed that exposure to cowpox could be used to provide protection against smallpox. He tested his theory on James Phipps, the nine-year-old son of his gardener. 

Jenner inoculated material from the cowpox sore on the hand of milkmaid Sarah Nelmes into the arm of Phipps, and exposed him several times to the variola virus. Surprisingly, Phipps never developed smallpox. 

After conducting more experiments, Jenner published his treatise "On the Origin of the Vaccine Inoculation", in 1801, in which he summarised his discoveries and expressed hope that the "annihilation of the smallpox, the most dreadful scourge of the human species, must be the final result of this practice."

Vaccination was gradually accepted, and replaced the practice of variolation. In the 1800s, the virus used to make smallpox vaccines changed from cowpox to vaccinia virus. 

The Kingdom of Bavaria was one of the first countries to introduce compulsory vaccination according to Jenner's method. On August 26, 1807, the Royal Bavarian Government Gazette published a decree "concerning smallpox vaccination to be introduced by law in all provinces." 

In the Kingdom of Bavaria, vaccination certificates were issued after successful vaccination against smallpox. These certificates were usually simple slips of paper. The only exception was a certificate issued in Graz, Styria, in 1855, which depicts Jenner, milkmaids, children, and a cow. 

The vaccination set for smallpox was made in Tuttlingen, Germany, and was manufactured between 1920 and 1930. It consisted of a knife, which was sterilised before being dipped into the vaccine. Then, the vaccine was inoculated into the upper arm of a person with two small cuts.

A few days after the vaccination, a small pustule was formed on the upper arm, which scarred characteristically, indicating that the vaccination was successful. 

Due to the success of vaccination, smallpox was eradicated, and no cases of naturally occurring smallpox have occurred since 1977. 

On May 8, 1980, the 33rd World Health Assembly, the decision-making body of the World Health Organization, declared the world free of smallpox. This was almost two centuries after Jenner hoped that vaccination could annihilate smallpox.

For his contribution to Immunisation, Jenner is also known as the "father of immunology".

Imvanex is the vaccine currently approved for vaccination against smallpox, and is developed by Bavarian Nordic based on the Modified Vaccinia Ankara virus strain. The vaccine can be injected subcutaneously and is approved for inoculation in people with immune deficiencies. Despite the fact that smallpox is considered eradicated, samples of the virus are still stored in research laboratories in the United States and Russia.

Spotted Fever Vaccine

European typhus fever, also called "spotted fever" and "ship fever", is different from typhoid fever. For generations, the disease was the scourge of armies, and still flourishes in Poland, Russia, and the Balkans. Spotted fever is caused by a bacterium called Rickettsia prowazeki, which dwells in the intestines of filthy little insects. The bacteria is transmitted by lice and fleas. 

The infection does not occur when a louse bites; rather, the bacteria are found in lice faeces, which enter the host's body through the bite wound.

Professor Rudolf Weigl of the University of Lemberg, Poland created a vaccine for spotted fever. The vaccine did not provide full immunity against the disease, but substantially reduced the symptoms. 

The vaccine provided protection against severe forms of the disease for at least one year. Weigl obtained his vaccine from infected lice intestines. 

According to Google Arts and Culture, Weigl managed to save the lives of thousands of people, including Polish University professors and Jewish citizens, by classifying their dangerous work as "louse-feeders" as "important to the war effort". Louse-feeders were human sources of blood for lice infected with spotted fever, which were then used to research possible vaccines against the disease. This was a job in interwar and Nazi-occupied Poland, at the Lviv Institute for Study of Typhus and Virology, and the associated Institute in Krakow, Poland. Weigl and his wife were some of the earliest lice-feeders. 

Typhoid Fever

Typhoral was a solid vaccine used for oral inoculation against typhoid fever in the 1940s. 

Typhoral contained killed typhoid bacteria Salmonella typhi and paratyphoid bacteria Salmonella enterica, in order to stimulate the immune system to produce antibodies. 

The vaccine provided protection for about six to 12 months. 

Currently, a live vaccine containing non-disease-causing Salmonella typhi bacteria is used for oral typhoid vaccination.

Polio Vaccine

People were vaccinated against Polio for the first time in West Germany, in the year 1956. A vaccine developed by US physician and immunologist Jonas Salk was used. 

The vaccine, called Virelon, contained killed poliovirus. However, only a few people agreed to get themselves vaccinated against Polio. Salk became a national hero when he alleviated the fear of polio with his vaccine, approved in 1955. However, Salk's vaccine was not the last polio vaccine. Albert Sabin, a Polish-American researcher, introduced an oral vaccine in the United States in the 1960s which replaced that of Salk. 

Sabin's live vaccine was available on sugar cubes. Its motto was "oral vaccination is sweet!". 

Between 1963 and 1999, Sabin's vaccine largely replaced Salk's vaccine everywhere in the world, according to the Smithsonian National Museum of American History. However, the live virus in the vaccine occasionally became strong enough to cause the actual disease, because of which Salk's killed-type vaccine replaced the live-type vaccine in the US.

Tetanol Vaccine

Tetanus, caused by Clostridium tetani, is usually fatal. However, it is the toxins produced by the bacteria, rather than the bacteria themselves, which primarily cause symptoms, according to an article published by Smithsonian institution. The same is true for diphtheria and pertussis. Currently, tetanus, diphtheria, and pertussis can be addressed by a single, combined vaccine. 

A vaccine to prevent tetanus, called tetanus toxoid, was introduced in 1924. Tetanus toxoid is an inactivated form of the toxin, which teaches the body to recognise and produce antibodies against the toxin, but is not able to damage the body itself. The vaccine was not frequently used until World War II, during which it became one of the routine vaccinations given to all American soldiers.

The pure toxin is converted into a non-toxic form called toxoid by treatment with formaldehyde. The toxoid is adsorbed to a mineral carrier such as aluminium hydroxide, and serves as a vaccine. 

Due to routine vaccination in the United States, death from tetanus has become rare. However, it is important to repeat a vaccination booster every ten years to keep that 

immunity. People who do not contract tetanus can be treated with a modern form of antitoxin, called tetanus immune globulin. 

Influenza Vaccine

Each winter season, the World Health Organization selects different virus strains which are likely to be responsible for influenza illnesses in a particular hemisphere during the respective flu season. 

The Influsplit Tetra vaccine is indicated for the prevention of the genuine viral flu or influenza in adults and children aged six months and above, caused by the two influenza A virus subtypes and the two influenza B lineages. These strains are contained in the vaccine. 

Combination vaccines — One Prick, Triple Protection

A single prick can protect one against mumps, measles, and rubella, when they are inoculated with a combination vaccine. 

The MMR (mumps, measles, rubella) vaccine "Priorix" is a combination vaccination. 

Combination vaccines were first used in the 1970s. The protective effect is not compromised, and fewer additives make them better tolerated. Also, only one appointment with the doctor is necessary. 

Other combination vaccines include those for tetanus, diphtheria,  pertussis, and polio, or Hepatitis A and B.

HPV Vaccines

German Nobel laureate Harald zur Hausen had proved that infection with human papillomaviruses (HPV) or wart viruses plays a decisive role in the development of cervical cancer or cervical carcinoma. The discovery was important because it led to the development of HPV vaccines.

Available since 2006, HPV vaccines specifically protect against certain sexually transmitted human papillomaviruses. 

Gardasil 9 is a new nine-drug vaccine which provides protection against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58. The United States Food and Drug Administration (FDA) approved Gardasil 9 in 2014. 

Gardasil 9 is produced through genetic engineering and contains only non-infectious viral envelopes.

Ervebo Vaccine

Ervebo vaccine is an Ebola vaccine that prevents Ebola caused by the Zaire ebolavirus. It is manufactured by Merck. The Ebola virus is one of the deadliest viruses in the world. 

The genetic material for a vaccine antigen is inserted into a carrier virus, which is then injected into the Ervebo vaccine. The protein of the virus' genetic material is incorporated into the surface of the vector, which is then introduced into the body of the human. 

The proteins trigger the production of antibodies in the vaccinated person. Ervebo is the first new vector technology-based vaccine to be approved. 

Pfizer-BioNTech Covid-19 Vaccine

Pfizer-BioNTech is an mRNA-based vaccine developed in the year 2020 by German pharmaceutical company BioNTech in collaboration with US pharmaceutical company Pfizer against SARS-CoV-2, or the novel coronavirus.

Since naked mRNA is physically and thermally unstable, it cannot reach the site of action without being degraded. In order to avoid this and to make sure that the vaccine is effective, the mRNA is packaged inside lipid nanoparticles called lipid beads. When these are injected into the body of a person, the cells take up the lipid beads, and produce the S protein, or the spike protein on the genetic material. 

The immune system recognises the spike protein as foreign, stimulating the production of protective antibodies.