Viruses are small molecules of DNA or RNA covered by a protein structure. They are not fully considered as living beings because when they are outside of the organism they are not alive, they are considered as microscopic parasites that need a host to live. When they colonise an organism they start to replicate itself resulting in multiple copies, while they lose this capacity of replication when they are outside the body. In other words, they need the host to live.
These copies are many times imperfect, there are mistakes in the replication process which lead to mutations. Mutations are the key of the evolution process. These are aleatory changes that could be helpful or harmful for the virus. Helpful mutations make the virus more adapted to the environment, in other words, the virus is more adapted to the host. Those varieties that have helpful mutations can compete better and be more successful than the others, replacing other varieties that are less adapted. Harmful mutations can lead to the infeasibility of the virus.
This success of the viruses can be appreciated by creating a fatality-infectivity ratio. Those viruses that end with the host’s life in a few days are not very successful since the host’s death means the death of the virus, it can not replicate and infect other individuals. The Ebola virus could be a good example, this virus has a fatality rate of 50%, which means that it kills approximately half of the patients. For this reason Ebola outbreaks are well located in the map and short in time. It has no time to spread itself through the population and cross the borders.
On the other hand, viruses like flu or influenza are widely spread around the world. They are very infectious and the fatality rate is minimal. The infected host may have a headache, blocked up nose, low temperature, mild symptoms that allow him to continue with his life, going to work and infecting more individuals. The virus is jumping from a host to another, infecting and living.
It is not necessary to be a prestigious virologist to observe the evolution process of the viruses. COVID-19 is a good example of that. In the first global wave it has a high infectivity rate and a low fatality rate (5-2%), enough to fill the hospitals and to establish an isolation period and close businesses. It has mutated giving place to different varieties, each one more contagious than the previous one. The virus is adapting to be more contagious and less lethal. In the last wave caused by the omicron variety, there is a huge level of cases, whereas the cases of death are minimal.
These facts make us believe that COVID-19 could become a seasonal virus like flu or influenza with many cases and a low number of deaths and the restrictive measures will not be necessary. The “aim” of the virus is to infect and not to kill since it depends on the host to live.
Written by Sara García Sánchez
Message to reader: Any information on this blog is for informational purposes only. It is not intended in any way to replace professional figures in the medical and consultancy fields.
Messaggio al lettore: Ogni informazione presente in questo blog è puramente a scopo informativo. Non si intende in nessun modo sostituire figure professionali in campo medico e di consulenza.