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Shafia London.
Shafia London.
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By Shafia London

What makes Covid-19 more dangerous than seasonal flu?

COVID-19 and the Flu both cause fever, cough, body aches and fatigue; sometimes vomiting and diarrhea and pneumonia. They can both be mild or severe, even fatal in rare cases. Both can be spread from person to person through droplets.

“So why aren’t people this worried about normal flu?” This has been the refrain of many since the COVID-9 Pandemic first emerged at the very end of 2019. It is a common and understandable comparison, but this conflation is wrong for several reasons.

  1. Cause

COVID-19 is caused by one virus, the novel 2019 coronavirus, now called severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2. The flu is caused by any of several different types and strains of influenza viruses.

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  • Contagiousness

Disease experts agree that Covid-19 spread more easily than seasonal flu. The infectiousness of a disease is defined by the reproduction number, referred to as the R naught. R naught is a mathematical equation that shows how many people will get sick from each infected person. The R naught fluctuates over time as scientists gather more data, and it can vary depending on where someone lives.

WHO has estimated the R naught of COVID-19 to be around 1.95 and other estimates put it around 2.2, meaning about two people will catch the virus from every person who already has it. For seasonal flu that number is about 1.3. That difference does not seem so big. However, after 10 rounds with a R naught of 1.3 for the flu, 56 total people will get sick. With a R naught of 2, after 10 rounds, more than 2,000 people will get COVD-19.

The R naught can be heavily reduced, depending on what a nation does to contain the virus, which is why officials scramble to close businesses and keep people indoors. If the R naught is higher than 1, it will spread, and it will be contagious. The R naught can also dramatically increase if a country does nothing. Without any containment measures, technically it can spread to the whole population. Some scientists predict half the world’s population will eventually get it.

Understanding the main reason for the contagiousness is critical. From the moment you are infected with COVID-19 it takes 5- 14 days to feeling symptoms, this is called the incubation period. Early research show you can be contagious during most of this period. The Flu on the other hand has an incubation of just 2 days. You can be contagious and spread it around for up to 14 days before you even realize you are sick. The Flu on the other hand, you get sick and in 2 days you feel sick.

  • Vaccines

Humans have lived with influenza for more than 100 years. A vaccine is available and effective to prevent some of the most dangerous types or to reduce the severity of the flu. The more immunized people, the more they can shield others from getting it. Health authorities regularly complain that not enough people receive the flu vaccine to guarantee “herd immunity”.

Covid-19 is a totally new virus in humans. We do not have any natural immunity or vaccines against Covid-19. And although more than 80 per cent of Covid-19 cases are mild, this makes it more likely that it will spread without being detected.

  • Death rate

Tens of thousands of people die from the flu but Covid-19 is more deadly than seasonal flu. Only 2% of people with the flu need to be hospitalized but 20-30% of people who test positive for COVID-19 do. Based on the WHO’s most recent mortality rate of 3.4%, the COVID-19 outbreak is shaping up to be at least 34 times deadlier than the flu, which has a mortality rate of about 0.1% and kills  290,000 to 650,000 people per year across the globe. If the current global mortality for CV-19 rate holds at 4.5%, it would make this coronavirus 45 times deadlier than the flu.

A variety of factors affects the mortality rate: geography, the quality of health care, age of the population, lifestyle, and underlying conditions. In Italy, it is about 10%. In Iran, it is about 7.6%. In Germany, it’s less than 1% and in the U.S., where the outbreak is just getting underway, it’s about 1.5%.

“There is still considerable uncertainty around the fatality rates of COVID-19 and it likely varies depending on the quality of local healthcare,” said Francois Balloux, Professor of Computational Systems Biology at University College London.

Mortality rate generally drops as testing rises and more patients are identified. More cases are being identified, to be sure, but people have been dying at a faster rate.

The only defense we have against COVD-19 is to remove ourselves from the virus path through physical distancing. We can take ourselves out of the chain by physically  removing ourselves from others and staying home as much as possible. But that only works if each of us takes it seriously. Now is not the time to be numb. Now is the time to be vigilant.


Shafia London holds a BSc (1st Hons) Major Biochemistry and Double Minors in Communication and Human Resource Management from the University of the West Indies. She is a MSc Biochemical Engineering Graduate of the world-renowned University College London. Before returning to the Caribbean, she worked briefly as a researcher with University College London studying the use of Pichia pastoris in commercial vaccine production through recombinant DNA techniques. She then switched to business and is now completing an MBA and is the Commercial Manager, Banks Holdings Ltd group of companies – manufacturers of Banks beer, Deputy Beer, Plus, PineHill Dairy juices and Milks among other popular products