For the last five months or so, the world has been swept away by the Covid-19 pandemic.
Until now, it has claimed the lives of over 800,000 people.
And a good amount of time passed before Russia bestowed upon the world the closest thing to a workable vaccine.
Russian President Vladimir Putin announced the world's first registered Covid-19 vaccine, Sputnik V, which is named after the space satellite launched by Moscow in 1957.
The vaccine has been created by the Gamaleya Scientific Research Institute of Epidemiology and Microbiology, a medical institute located near Moscow.
For months, scientists across the world have been slaving relentlessly to develop a successful cure or treatment for the deadly virus.
But a hundred percent effective vaccine can take years, even decades, to be developed.
The extensive vaccine-making process, once developed, could differ largely from the real-life effectiveness in comparison to the projected effectiveness - ultimately wasting the time and resources invested.
But Covid-19 is not the first pandemic that the Earth has faced.
Before Covid-19, pandemics shook the Earth more than once and the human race has fought back each time.
The Black Death
Although The Black Death took place during the Middle Ages, the disease is still active in certain areas around the world.
A plague outbreak in Madagascar attracted widespread attention and panic as recently as 2017.
This plague pandemic resulted in the invention of quarantine.
As the name suggests, the pandemic was perpetual and merciless in every sense.
After the first wave, The Black Death returned to Europe after 800 years.
It resulted in the deaths of 200 million people throughout human history.
Unfortunately, no vaccine is available even today.
However, the spread of plague can be prevented by modern antibiotics since it stems from bacteria.
Even so, researchers believe that a vaccine is the most viable option to fight the disease in the long-run.
Many attempts to create a plague vaccine have failed in the past but a 2018 study by the World Health Organisation (WHO) created a "Plague Vaccine Target Product Profile" that crossed out 17 possible candidates for vaccine approval.
It is currently undergoing clinical trials.
The US Army physician Frederick F Russell developed the first US typhoid vaccination in 1909.
For several following years, the vaccine was used for strictly military purposes.
In 1914, however, it was available for usage by the general American public.
Although the typhoid vaccine was commercially developed in 1909, research into these efforts first began in 1896 by German scientists after the bacteria responsible for the disease was discovered in 1880.
The contamination of typhoid fever has decreased in the recent years but it still remains a deadly disease that can be spread widely through unclean food and water.
The bacterial disease poses significant threat throughout developing nations, mainly targeting Southeast Asia, Africa, and Latin American regions.
Another deadly plague that hit Europe, Asia and Arabia was smallpox.
Centuries later, smallpox became the first virus epidemic to be eradicated by a vaccine - which is considered one of the biggest achievements in public health history.
But it took several centuries for the smallpox vaccine to be developed.
Although scientists believe that the outbreak of smallpox dates all the way back to the Egyptian Empire of the 3rd Century BCE, the origins still remain undetermined.
The disease spread across the globe by the 18th century due to colonisation and had a devastating mortality rate of up to 30 percent.
The first successful smallpox vaccine was developed by English physician and scientist Edward Jenner in 1796.
But it was not until the 1950s that vaccine treatments began to effectively eradicate the disease in some parts of the world.
Almost two decades later, in 1967, a global effort that provided a higher level of vaccine production and an advancement in needle technology eventually led to the eradication of the disease by 1980.
To date, smallpox remains the only disease to have been completely eliminated around the world through vaccination efforts.
From 1918 to 1919, a new pandemic named influenza spread globally.
It ended by establishing a tragic history of killing millions of people worldwide.
And during those times, there were no known cures or vaccinations for the virus.
The first reliable documents regarding influenza-like illness syndrome date from 1510, when the virus spread from Africa to Europe, but medical research began in the 1930s, and it took decades of research to understand the virus.
Thomas Francis Jr, MD and Jonas Salk, MD served as the lead researchers at the University of Michigan in the 1940s to develop the first inactivated flu vaccine with support from the US Army.
The vaccine was tested on fertilised chicken eggs in a method that is still used to produce most flu vaccines today.
The vaccine was first approved in 1945 for use in the US.
But only two years later researchers concluded that seasonal changes in the composition of the virus rendered existing vaccinations ineffective.
They also discovered multiple new strains of the virus each year - causing them to tweak the vaccine every year.
Today, WHO designs seasonal flu vaccines using data gathered from influenza surveillance centres.
Yellow fever turned into a pandemic by the end of the 19th century after it caused deadly epidemics throughout human history for more than 500 years.
Scientists could not unearth anything about the disease for a long time and early vaccination efforts in 1918 by researchers at the Rockefeller Institute mistakenly focused on bacterial transmission when the disease was actually caused by a virus.
Prior to the development of a vaccine for the deadly fever, South African-American virologist and physician Max Theiler proved otherwise and the faulty vaccine ceased production in 1926.
Eleven years later in 1937, Theiler created the first safe and effective yellow fever vaccination, which has since become the universal standard.
Theiler became the first and only scientist to receive a Nobel Prize for the development of a vaccine in 1951.
He contributed to minimising the spread of yellow fever and rectifying the years of misled research.
The Centers for Disease Control and Prevention states that varicella is an acute infectious disease caused by varicella zoster virus (VZV).
Since primary varicella infection, commonly known as chickenpox, shows similar symptoms to smallpox, the disease was misdiagnosed as smallpox until the end of the 1800s.
Scientists succeeded in distinguishing chickenpox from herpes zoster in the 1950s.
VZV was isolated from vesicular fluid of both chickenpox and zoster lesions in cell culture by American virologist Thomas Weller in 1954.
Subsequent research in Japan led to the development of the first vaccine for chickenpox two decades later.
The vaccine was licensed for public use in the US in 1995.
Cholera, another pandemic that killed tens of thousands globally, is a highly contagious disease Bangladesh is familiar with.
Origins of the disease trace back to approximately 500 BC, surfacing in Bangladesh in 1991.
As per the 2018 publication "The Journal of Infectious Diseases", there are at least a million cases and approximately 4,500 deaths each year due to cholera in Bangladesh alone.
Spanish physician Jaime Ferrán became the first to create a cholera vaccine in 1885.
It was approved by the FDA in 2016.
His vaccine helped 50,000 people in Spain during a major cholera epidemic.
Ferrán became the first one to do a mass-vaccination as well.
Extensive studies and researches over the centuries reinforced the knowledge on the theory of herd protection.
Herd protection proved that vaccines could help both direct recipients and surrounding neighbours from contracting cholera.
Polio, before it became an epidemic in the late 1800s, had been affecting human populations for thousands of years.
As the century turned, the virus tore through the US leaving thousands permanently disabled.
To understand polio, it took researchers a few decades and to develop a vaccine, it took them a few more.
The first vaccination attempt was done on monkeys and later on children in 1935.
It, however, yielded poor results and two more decades of meticulous research paved the way for a set of effective vaccines by Jonas Salk in 1953 and Albert Sabin in 1956.
The US adopted Salk's vaccines in 1955 after testing it on 1.6 million children.
Relentless research till the 1980s gave way to even more effective and efficient production of the vaccines.
Polio is another disease that has severely affected Bangladesh for a long time.
After years of wreaking havoc on thousands of people, Bangladesh was declared a polio-free country by the WHO in 2014.