Why Corona Virus Spreads so Fast?
Authors: Gilani Syed Amir 
Published: March 2021

Coronaviruses are a family of common viruses that affect mammals and birds and most of the time the strains caused are mild symptoms like a common cold, fever, cough, and runny nose. Given the historic records, there has been cases of diseases every once in a while with strain that were new and were particularly lethal – they could spread through the world quickly and with more concerning outcomes. Prior examples of such diseases would include the SARS epidemic which is not exactly the same as COVID-19 that we're experiencing but some of the same features apply in that it is a corona virus. It is a new strain that we have not experienced before and it's spreading very rapidly. It is empirically understood that our world contains wide range of different viruses and every day since our birth we come into contact with them but we do not develop symptoms because of what's called herd immunity. It means most of us have some level of recognition with our immune system to the common viruses which is why some of us still get sick with colds and influenza. These illnesses tend to not overtake our healthcare system because people don'tget sick all at once and even if so at least they usually do not get sick to a concerning level (easily treatable). The case is different when a new virus such as the one causing COVID-19 right now, appears in the world –and because we have not developed herd immunity to it, it tends to spread very quickly and it takes a while for that herd immunity to catch up. In order to evaluatespecifically how a virus is spreading through the world and affecting populations one needs to look at how quickly or how widespread it already is and also how lethal and fatal it has been. The fact is these two factors don't always go together rather they're independent to one another, coronavirus so far is making a big impact because of how widespread it is due to how easily and how quickly it can spread through our community. As for how lethal it is and how that affects our health care system; the most common symptoms are fever dry cough and tiredness and critical symptoms include difficulty acute respiratory distress syndrome (ARDS) chest pain or pressure and loss of speech or movement. It is to be noted that the timeline of virus spread matters so the WHO has declared COVID-19 a pandemic. This is a public health concept that means a virus or an illness actually that is spreading as separate areas of the world concurrently. It should also be kept in mind that this term “Pandemic” only describes how prevalent and widespread it is, it does not describe how lethal it is. So why is the current virus causing COVID-19 is so good at spreading. As mentioned earlier that since there is no herd immunity and as it spreads, none of us have encountered it before our bodies are not prepared and cannot fight off the virus very quickly. Furthermore, because it's actually not that lethal since 80% of people who suffer from it have either very mild symptoms or no symptoms and even those who go on to develop symptoms can have a very long latent period of up to 10 days where they are contagious. The problem that it is so widespread because 80% of people have no symptoms or are very mild symptoms and can recover easily on their own. 15 percent would probably need hospital care and 5 percent likely needs Intensive Care Unit level critical treatment. Further the most vulnerable population arethe elderly or people who are already sick but the fact that it spreads quickly means that the 5% that needs intensive care will need it very quickly and in a concentrated period of time. This is very different from something like Ebola virus where by the time one will have it and he/she is contagious plus the symptoms were very dramatic and it could be easily determined who has it. In case of COVID-19, most people spend a long time able to pass a virus without either knowing it or with very mild symptoms. Having mentioned that it's almost impossible to completely shut down the spreading of this virus without dramatic measures to contain people in such a highly mobile and globally accessible world. Because we don't know who is sick especially in the earlier parts of the epidemic and that's why we're seeing countries one by one taking really dramatic shutdowns. It is worth mentioning that flu that also puts a percentage of people in critical conditions and leads to death in especially in the vulnerable populations but if we look at flu season around the world it is a six-month period of time. Putting that into perspective the hospitals and personnel; considered limited resources, and the respiratory machines that are needed to support people and the doctors to see them - might be able to support people periodically needing it over a sixmonth period of time. But the case of COVID19 is different, given the fast concentrated spike of critical patients, the systems can get overwhelmed like seen in Italy and China. So the 5% that need critical care might not have the doctor, the ventilator and the infrastructure to help them through the worst of the illness. That's is the reason of spread and lethality of COVID-19 - the delayed response and conjoined with difficulty in containing a virus that spreads quickly through healthy people has been the crux of the problem.