A year after the first cases of Coronavirus appeared on the European continent
Today, thanks to the numerous scientific studies that have emerged in recent months , we can take stock of the 5 things that are clear today about COVID-19.
NB This article was created leaving aside personal and biased thoughts, but simply combining all the certain data on Coronavirus to provide as subjective a point of view as possible on the situation we are experiencing.
Without further ado, let's find out together what is clear about COVID-19 today.
1. Transmission mode
The main mode of transmission of this coronavirus is through droplets and high-concentration aerosols .
It occurs when an infected person coughs or sneezes near other people and they ingest or inhale the droplets produced.
2. Asymptomatic infections have the same infectivity as symptomatic infections
A British study found that a 53-year-old patient with an asymptomatic COVID-19 infection can cause 11 infections .
Another report found that an asymptomatic person who lived 19 days after infection (before confirmation) without isolating could have infected 5 people.
These that you have just read are only two of the many cases recorded, but what everyone confirms is that asymptomatic people can play a significant role in the transmission of the coronavirus and therefore represent a further challenge for infection control.
3. Only by tracing asymptomatic people will the epidemiological potential of COVID-19 be clarified
The challenge is very difficult, but it is the only way to understand the true spread and universality of the disease .
Unfortunately, there are many studies on the incidence of asymptomatic infections, but each study has its limitations.
First, due to insufficient awareness of asymptomatic infections and limited detection capabilities in the early stage of the epidemic, he thinks that it is estimated that 1.6% of the Chinese population may have been asymptomatic and unfortunately this figure is a huge underestimate.
In contrast, another study investigated 565 Japanese citizens evacuated from Wuhan in late January and found that the incidence of asymptomatic infections was as high as 30.8%.
Another example is the cruise ship “Diamond Princess”, which was isolated in Japanese waters in early February due to COVID-19 infection which found that the incidence of asymptomatic infections had risen to 51.7%.
Some researchers have suggested that the two studies you just read overestimated the incidence, but in reality the fact is that: a person is indeed at higher risk if he or she has close contact with diagnosed or suspected infected people in a relatively small space .
4. No diagnostic test has 100% sensitivity and specificity
There are more than 800 diagnostic tests, more than 250 of which are so-called rapid tests that take less than 30 minutes to generate a result.
Although the use of point-of-care (POC) immunoassays remains universally accepted as part of the strategy to control the spread of the virus, no test guarantees 100% sensitivity and specificity.
This fact must always be taken into account when diagnostic results are translated into clinical practice (e.g. when dealing with a patient who shows symptoms, but who tests negative for coronavirus).
The reason for this is that there is no clear gold standard for available tests for a pathogen that has only been known for a year .
The analytical specificity of a molecular COVID-19 test is its ability to search exclusively for limited off-target measurements while excluding others as a priority.
5. Why There Are Major Limitations in Validation Studies of COVID-19 Diagnostic Tests
Overall, limitations of many of the published validation studies on COVID-19 diagnostic tests include: low sample numbers , differences in sample collection, storage , and processing processes prior to diagnostic testing (preanalytical bias), and lack of independent third-party validation .
All studies were performed using dispersed clinical parameters, a feature that also hampers the development of diagnostic tests during previous coronavirus outbreaks.
In conclusion
Today we looked at 5 things that are clear about COVID-19 a year into the pandemic.
We went to analyze scientific studies and research together to be able to give you a point of view as objective as possible because in this universe of information we realized that it is becoming increasingly difficult to differentiate certain data from interpretations or, even, from fake news.
Sources:
- J Microbiol Immunol Infect. 2021 Feb;54(1):12-16. Published online 2020-05-15. doi: 10.1016/j.jmii.2020.05.001
- Review Nat Rev Microbiol. 2021 Mar;19(3):171-183. doi:10.1038/s41579-020-00461-z. Epub 2020 Oct 14.
- Int J Mol Med. 2020 Nov;46(5):1599–1602. Published online 2020-09-18. Doi: 10.3892/ijmm.2020.4733
