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There are seven types of coronaviruses that naturally infect humans. Three of them, SARS-CoV-2, SARS-CoV and MERS-CoV can cause severe acute respiratory illnesses. By contrast, the rest four coronaviruses with the names: HKU1, NL63, OC43 and 229E usually cause much milder upper respiratory tract infections, and are therefore considered low-pathogenic human coronaviruses. Intriguingly, low-pathogenic human coronaviruses are more prevalent and manifest their symptoms in young children, contrary to the new coronavirus Sars-CoV-2, which might infect young children but it does not affect them with severe clinical symptoms (of course there are exceptions).

Given that these low-pathogenic human coronaviruses are continuously…

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5,000,000 lives. That is the number of lives saved globally every year because of vaccines.

Vaccines played a tremendously important role in the elimination of infectious diseases such as polio, diphtheria, neonatal tetanus, etc. Polio — a disease that causes paralysis and death — wreaked havoc in the 1950s and 1960s and has now disappeared with the exception of Afghanistan, Pakistan and Nigeria (where no vaccination takes place). The same goes for diphtheria and tetanus. As Dr. …

Tracing the origin of a new virus. . .

Image source: TravelCouples/Getty Images

Epidemics made their appearance around 12,000 years ago during the Neolithic period. Starting from this period onwards humans developed gradually densely populated agricultural communities, allowing microbials to spread easier and faster through several means of transmission (water, food, air, person-to-person contact, etc.).

But while there are 10 nonillion (10 to the 31st power) viruses on our planet — more than the number of stars in the known universe! — human species manages to survive quite well and with a relatively low frequency of virus-caused illnesses in this virus-filled world. …

How was the trial designed by Pfizer & BioNTech? What does a 90% efficacy rate mean? IS IT SAFE?

In July 2020, Pfizer and BioNTech initiated a late-stage (Phase 3) clinical trial on a coronavirus vaccine. The vaccine uses part of the viral RNA packaged in nanoparticles of oily membranes. This small part of the viral RNA contains all the information for the Spike protein, the famous protein helping the virus dock onto human cells’ membranes and get inside them. Why packaged in nanoparticles of oily membranes? Simply because our cells are covered from membranes made of lipids, which — due to their biochemistry (non-polar and hydrophobic core) — make it difficult for big substances, or charged molecules to…


Figure 1| Antibodies: Y-shaped proteins that bind to the body’s foreign invaders (red sphere). Image: © Shutterstock

One new vaccine against SARS-CoV-2 is almost out and while this is already considered a big breakthrough for the novel coronavirus pandemic, scientists around the globe remain conservatively optimistic about it.

There are three key points we should keep in mind according to the scientific community:

1. While the Phase 3 trial of Pfizer and BioNTech looks indeed very positive, it has not finished yet. The vaccine is based on preliminary analyses and more data are needed to enhance our knowledge about its safety and its potential for big scale production.

2. Even if it is given a green light…


Image by Christian Ohde

SARS-CoV-2, the novel coronavirus that causes COVID-19 disease, is a virus keeping all its genetic info in a single strand of RNA. RNA — the ‘cousin’ of DNA — is a polymeric molecule essential in many biological procedures with regards to the regulation of genes. DNA & RNA molecules are nucleic acids and along with lipids, proteins, and carbohydrates, they constitute one of the four major macromolecules essential for all known forms of life. Like DNA, RNA is assembled as a chain of nucleotides made of a combination of four different ‘letters’…

What is UV Light?

Ultraviolet (UV) light is a type of electromagnetic radiation invisible to most humans and emitted mainly by the sun. However, UV can be released by artificial sources too such as electric arcs and specialized lights (e.g. tanning lamps). The wavelengths of UV rays range between 200 and 400 nm, which are shorter than the wavelengths of violet light (hence the name ultra-violet. Violet is at the higher end of the visible spectrum with a wavelength of around 380–450 nm).

How can UV affect our DNA?

DNA is our genetic code, the precious molecule containing all the information necessary to make up a living organism and it…

A few words about one of the most important organs of the human body: The skin

The skin is our largest and most visible organ, covering nearly 2 m2. As the interface between the organism and the environment, the skin has a multitude of functions; from maintaining temperature homeostasis and serving as the first line of defense against pathogens to performing important metabolic processes and protecting against the harmful effects of Ultraviolet Radiation (UVR). It is therefore a highly complex organ made of many cell types and can be divided into three main layers. …

The four scientists with key roles on the elucidation of the structure of DNA. From left to right (random order): Maurice Wilkins, Rosalind Franklin, James Watson and Francis Crick.

One of the most important scientific discoveries of the past century, the unravelling of the structure of our blueprint (DNA), was not made overnight. Important pieces of work, which can be traced all the way back to 1800s, provided crucial steps and stepping stones towards the final discovery of the double-stranded structure of DNA that culminated officially in 1953.

Rosalind Franklin, a scientist born to Jewish parents in 1920 in London, joined King’s College London in 1951 after having received her PhD in the field of Chemistry at the University of Cambridge; a great achievement given the timeframe of this…


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Before we dive into vaccines and the so-far developments, let’s start with the basics, namely the immune system.

The immune system is our body’s defense and attack system against any form of infection and is comprised of an interconnected network of proteins, cells, and organs. When our body is confronted with a pathogen, our immune system follows two main strategies; a generic response (innate immune response) and a more elaborate, complexed and targeted response (adaptive immune response). The generic (innate immune) response is the first line of defense and attack. …

Theodora Chatziisaak

A biochemist who aspires to demystify complex biological concepts and make everyone understand the beauty of life’s phenomena. Read more:

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