5 things that are clear today about COVID-19

One year after the appearance of the first cases of Coronavirus on the European continent

Today, thanks to the numerous scientific studies that have emerged in recent months we can make a point of the situation on the 5 things that are clear today about COVID-19.

NB This article was created leaving aside personal and partisan thoughts, but simply combining all the certain data on the Coronavirus to provide as subjective a point of view as possible on the situation we are experiencing.

Without waiting any longer, let's find out together the things that are clear today about COVID-19.

1. Mode of transmission

The main mode of transmission of this coronavirus is through droplets and highly concentrated aerosols.

It occurs when an infected person coughs or sneezes near other people and the latter swallow or inhale the droplets produced.

2. Asymptomatic infections have the same infectivity as symptomatic infections

A British study has shown that a 53-year-old patient with an asymptomatic COVID-19 infection can cause 11 infections.

Another report highlighted that an asymptomatic person who lived 19 days after infection (before confirmation) without isolating himself could have infected 5 people.

These you have just read are only two of the many recorded cases, but what everyone confirms is that asymptomatics may play a major role in the transmission of the coronavirus and thus pose an additional challenge for infection control.

3. Only by tracing the asymptomatics 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, thinks an estimated 1,6% of the Chinese population may have been asymptomatic and unfortunately the figure is greatly underestimated.

In contrast, another study investigated 565 Japanese citizens evacuated from Wuhan at the end of 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 the 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 have just read overestimated the incidence, but in reality the certain fact is that: a person really has a higher risk if they have close contact with diagnosed or suspected infected people in a relatively confined space.

4. No diagnostic test has 100% sensitivity and specificity

there over 800 diagnostic tests, more than 250 of which are so-called rapid tests which take less than 30 minutes to generate the result.

While 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 consideration when the diagnostic results are translated into clinical practice (e.g. when you are faced with a patient who shows symptoms, but who is negative for the coronavirus from diagnostic tests).

The reason for this is that there is no clear gold standard for testing available 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 off-target measurements excluding the others as a priority.

5. Because there are major limitations in validation studies of COVID-19 diagnostic tests

In general, the limitations of many of the published validation studies on COVID-19 diagnostic tests are: the low number of samples, differences in collection processes, storage ed processing of samples before diagnostic tests (preanalytical bias) and the lack of third-party validation independent.

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 analyzed 5 things that are clear today about COVID-19 one year after the advent of the pandemic.

We went to analyze studies and scientific research together to be able to give you as objective a point of view as possible because in this universe of information we have 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 May 15, 2020. Doi:  10.1016 / j.jmii.2020.05.001
• Review Nat Rev Microbiol. March 2021; 19(3):171-183. doi: 10.1038 / s41579-020-00461-z. Epub 2020 October 14th.
• Int J Mol Med. 2020 Nov; 46(5):1599–1602. Published online September 18, 2020. Doi:  10.3892 / ijmm.2020.4733