What makes viruses so dangerous?

The most effective way to curtail their spread is through vaccines, but with vaccines only available for 1% of the world’s known viruses the challenge remains...

Medical workers near the Jinyintan hospital in Wuhan, China

Over 700,000 lives are taken by the AIDs virus every year. Hepatitis C claims the lives of over 200,000 people each year and haemorrhagic fevers caused by viruses such as Ebola have resulted in over 20,000 deaths.

Most recently, coronavirus has claimed the lives of over a thousand people and continues to wreak havoc across the world. The UK government has recently given the authority to forcibly quarantine people and keep them in isolation in an attempt to prevent the continued spread of this virus.

What is a virus actually?

A virus is a tiny infectious particle. They are much smaller microorganisms than bacteria, meaning they are only visible under an electron microscope. Viruses are made up of genetic material - either ribonucleic acid (RNA) or deoxyribonucleic acid (DNA), along with proteins and, in some cases, lipid envelopes. Viruses are not considered to be living organisms because they do not complete all of the seven life processes: movement, respiration, sensitivity, nutrition, excretion, reproduction and growth. They can only reproduce by infecting a ‘host’ living cell - such as an animal cell, plant, bacteria or archaea. Viral infections cannot be treated with antibiotics.

There are millions of viruses in the world’s oceans. Every millilitre of ocean water contains several million virus particles. If lined up end-to-end they would stretch 200 million light-years into space. Viruses kill cells, meaning they have a major impact on ocean ecology. 

Thanks to scientific research and investment from the most developed countries, progress has been made with regards to understanding how a virus penetrates a host cell and proceeds to spread. In theory, this information should provide scientists with enough to establish virus control procedures, along with creating antivirals, antibodies and vaccines. Unfortunately, the primary challenge they face is the lack of ability to cultivate and grow a virus in a laboratory setting. As a result, there is currently only knowledge of cell culture growth methods for 1% of all known viruses.

Viruses are everywhere...

The modern world is populated with over 7.7 billion people and this number continues to grow year on year. Worldwide travel is relatively simple and becoming increasingly cheaper. With more and more people frequently travelling between different continents, viruses can spread rapidly.

The seasonal flu virus or ‘influenza’ is spread across continents by the migration of birds and causes around 650,000 deaths each year. Due to imports, exports and many ways to travel across continents, viruses that were once confined to specific populations and continents have now spread beyond their ‘natural’ borders - causing epidemics and worldwide pandemics. 


In the case of the human immunodeficiency virus (HIV), this was initially spread via monkeys and then passed on to humans. It is understood that the HIV virus spread so rapidly due to the number of people with the infection travelling to different places while carrying the virus. 

Since its emergence in 1981, HIV has infected around 78 million people and caused approximately 32 million deaths. The molecular biology of this virus is now well understood and over 30 drugs have been developed that are capable of blocking the various stages of the viral replication - the process that makes the infection chronic. Though, despite extensive scientific knowledge of HIV, there is still no prophylactic and therapeutic vaccine that is able to prevent or eliminate the viral infection. 

It’s well-known that a vaccine is the most effective way of curtailing the spread of viruses. Vaccines are often composed of an extract of the pathogen in order to trigger an immune response. Once a virus has entered the body immune cells called lymphocytes respond by producing antibodies, which are protein molecules. These antibodies fight the invader known as an ‘antigen’ and protect against further infection.

Over the last two decades, vaccines have saved around 20 million lives. They are believed to have prevented around 500 million cases of disease and understood to have saved the health sector around 300 billion euros. Vaccines are currently available for diseases such as diphtheria, tetanus, polio, measles, mumps, rubella, pertussis, hepatitis B, Pfeiffer bacillus, pneumococcus and meningococcus C (a major cause of meningitis). 

Though there remains a plethora of other diseases with high mortality rates that are caused by viruses that have no approved vaccine - this is what makes many viruses so dangerous.


There is great concern globally about the emergence of new and re-emerging diseases caused by viruses. The most recent viral threat - coronavirus made its first appearance in China in  December 2019 and still remains unclassified as 2019-nCoV. Currently, the world’s scientific community is rallying together all possible strategic resources in an attempt to contain the spread of this virus. In China alone there are now 24,300 recorded cases of coronavirus and the World Health Organisation has warned the number of cases is likely to rise further. 

Mariano Esteban, a research professor at the National Centre for Biotechnology (CNB-CSIC), in Madrid said: “We are working hard on a vaccine to combat coronavirus 2019-nCoV. Without a doubt, it is necessary to get antiviral and antibody-based therapies as soon as possible to stop the infection by the coronavirus 2019-nCoV in people already infected.”

China began placing entire cities on lockdown in an attempt to stop the spread of the deadly virus on 23 January, when outbound trains and flights from Wuhan, the biggest city in Hubei province, with a population 11 million, were suspended. This strategy has continued across China. It is clear that this containment strategy adopted in China will serve as a reference for future planning in the face of the emergence of new viruses that are highly pathogenic for humans. It remains the responsibility of the World Health Organisation to establish the protocols for the control of global infectious diseases, which will continue to create a worldwide threat until more vaccines against viral infections are established. 

Katie Burt

Katie Burt

When not found with a laptop at my fingertips, it's likely I'll be running, swimming, attempting to cycle or seeking out decent coffee.

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