What Are Vaccines And How They Work?

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by Dr Sajad Bhat

Infectious diseases have always burdened our global society resulting in immense human suffering, a huge strain on our economy, medical systems and the loss of millions of lives. Pandemics like the Flu pandemics of 1889, 1918, 1957, the recent ones AIDS pandemic of 1981 and H1N1 Swine Flu pandemic of 2009 have ravaged humanity before.

A doctor from a protective booth takes samples of a Kashmiri woman in a Redzone area of Srinagar, on Thursday 30 April 2020. The administration is conducting a health audit of the entire population of Srinagar. KL Image by Bilal Bahadur

Since the first reports of Covid-19 from Wuhan, China in late 2019, this novel Coronavirus has rapidly spread worldwide, upending conventional life, locking people indoors, over-burdening health systems, closing schools, cancelling sports events, decimating stock markets, triggering job losses and border controls and causing masses of people to stockpile food and supplies.

According to the Johns Hopkins University, USA, which is tracking the outbreak, the confirmed death toll at the time of writing this surpassed 260000 while over 3 million cases stand reported in more than 200 countries and territories. An estimated 2.6 billion people – one-third of the world’s population – is living under some kind of lockdown or quarantine.

As the virus continues to spread, cities locked down, businesses downing shutters, factories shut and most travel on ice, economic paralysis follows in its wake. Economists anticipate the outbreak has pushed the world economy, which they believe is already in recession, to its sharpest rate (a 12% contraction) since World War II over January to March. According to the International Monetary Fund (IMF), Asian economies will see zero growth this year, for the first time in 60 years. The World Trade Organization, IMF and World Bank have predicted that this crisis will have a more devastating effect on trade (which could fall by up to a third) than the 2008 global financial crisis did, and the likes of which the world has not experienced since the 1930s Great Depression. According to Oxfam, the pandemic could push around half a billion people into poverty, and the number of people living in extreme poverty could rise by 434 million people to 922 million worldwide.

Coronavirus infections continue to surge and this pandemic threatens to become one of the most difficult health challenges faced by humanity in modern history. It is a vaccine what many see as the best hope to prevent the spread of the SARS-CoV-2 virus, which causes Covid-19. Right now, scientists around the globe are racing against time to develop an effective vaccine for the ongoing Covi-19virus. Worldwide, around 100 vaccine candidates are being investigated by various research groups in over 40 world-renowned institutions and vaccine companies at a record pace, and some already have begun the first phase of clinical trials.

Inventing vaccines was one of the world’s greatest achievements. There are now 26 vaccine-preventable diseases. With vaccines we have been able to reduce human suffering from fatal infectious diseases significantly, saving millions of lives. Vaccines like BCG, Influenza, Whooping Cough, Polio, Hepatitis B, Typhoid, etc. prevent outbreaks of deadly diseases and millions of deaths. Also, some diseases can cause prolonged disabilities which can take a financial toll on families because of lost time at work, medical bills or long-term disability care, however, these can be prevented by vaccines.

How do Vaccines work?

Vaccines greatly reduce the risk of infection by working with the body’s natural defences to safely develop immunity to a disease. To understand how vaccines work, it is helpful to first look at how the body fights illness/sickness. When disease-causing germs/pathogens, such as bacteria, viruses or parasites enter the body, they attack body cells and multiply. This invasion is called an infection, and the infection is what makes one sick.

A 1918 photograph showing the mass morbidity during the Spanish Flu that was a big killer in most of the world, especially Europe.

Using various tools (cells, proteins, sensors, etc.), the body’s immune system firstly recognizes these germs as foreign invaders secondly process them and finally eliminates them by producing proteins called antibodies and immune cells (T and B Cells – White Blood Cells). These immune cells and antibodies help destroy the germs that are making you sick. The immune system stores away a few of the cells as Memory Cells. These memory cells act quickly if the body encounters the same germ/pathogen again in the future, even many years later they will defend your body. Only now that your immune system is experienced at fighting these particular germs, can it destroy them before they have a chance to make you sick a second time. This is immunity.

Vaccines help develop immunity by imitating an infection. They develop immunity by causing the immune system to produce immune cells and antibodies without making you sick. Vaccines are made from the same germs (parts of them or their genetic material) that cause the disease.  For example, the Polio vaccine is made from Poliovirus, but the germs in vaccines are either weakened or killed so they won’t make you sick. The vaccine deceives the body into thinking an infection has occurred and the immune system attacks the harmless vaccine and prepares for invasions against the kind of germ the vaccine contained. After this process occurs the person becomes immunized against the germ. If re-exposure to the germ occurs, the immune system will quickly recognize the infection and remove it from the body. The vaccine gives the body an opportunity to be exposed to a disease and create an immunity without the person suffering the symptoms of the disease. The immunity from a vaccine can be short-lived or life-long, depending on the type of vaccine and the disease.

DC Srinagar, Dr Farooq A Lone, administering pulse polio vaccine to a baby at PHC Batamaloo on Sunday. (KL file Image)

Some vaccines may cause a little discomfort, pain, redness or tenderness at the injection site, this is minimal compared to the pain, trauma, and suffering of the diseases these vaccines prevent. Sometimes, after getting a vaccine, an imitation infection might cause some minor symptoms such as a fever or in very rare cases, an allergic reaction. Minor symptoms are normal and should be expected as they are a sign the body is building immunity. Some vaccinations require booster doses at regular intervals to boost up the body immunity.

Edward Jenner, inventor of Small Pox Vaccine

Vaccines are not only the most effective way of preventing the outbreaks of infectious diseases, but they are also a very powerful tool in controlling the spread of the disease. Vaccination is safe and one of the greatest scientific developments of the 20th century. The immunity due to vaccines is largely responsible for the worldwide eradication of smallpox, one of the most contagious and deadly diseases known to man. Deadly, or chronic infectious diseases that have a significant impact on human society, such as Ebola, polio, measles, mumps, typhoid, rubella, tetanus, diphtheria, smallpox and whooping cough have been restricted worldwide by the introduction of vaccines. According to the World Health Organization, vaccines save an estimated 2-3 million lives each year.

People are now eagerly waiting for and pinning their hopes on a vaccine to do the same for the Covid-19 virus and scientists worldwide continue to work toward creating more vaccines for other dreadful diseases that aren’t currently controlled by vaccination such as HIV/AIDS, RSV, Zika and Dengue Fever, etc.

Finally do remember to be a part of global immunity, vaccinate yourself and your children to make the world a safer, happier place, which is free from damaging diseases.

DR Sajad Bhat

(Author is working as a researcher in the areas of Infectious Diseases, Immune Responses, and Immunology at the Animal and Biosciences Research Department, Teagasc, Grange, Ireland, and currently in transition to move to Conway Institute, Unversity College Dublin, Dublin, Ireland. He has a PhD  (Microbiology- Infectious Diseases and Immune Response) from the University of the Sunshine Coast, Queensland, Australia, and MRes (Biomedical Sciences – Infections and Immunity) from St George’s University of London, London, UK. He did his MSc (Microbiology) from Bangalore University, Bangalore, India. The author has also worked as a Research Assistant in Immunology at King’s College London, UK, and Tutor in Biosciences course for the Bachelor’s program at the University of the Sunshine Coast, Queensland, Australia].

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