Covid-19: the order of appearance of symptoms would be different depending on the variant contracted, according to a study

What if the order of appearance of Covid-19 symptoms allowed you to know the type of variant that infected you? This is what a study published this Thursday, December 16, 2021 suggests in the journal PLOS Computational Biology. Based on a mathematical model, researchers at the University of Southern California analyzed the characteristics of American and Chinese patients during the first wave of the coronavirus.

And the results are intriguing. According to scientists, the order of symptoms is different: if the cough starts first in infected Americans, it is the fever that occurs first for Chinese residents. How to explain the difference?

The researchers based themselves on 373,883 cases in the United States, collected from January 22 to May 30, 2020, and almost as many in China during the month of February 2020, before establishing a whole bunch of probabilities on the order of arrival. symptoms.

According to their model, 76.9% of Chinese patients, 98% affected by the first appearance of covid-19, initially suffered from fever rather than cough, nausea or vomiting, while 47 , 5% of American patients, 70% contaminated by the “D614G” variant, were more likely to be affected by cough, before fever.

For researchers, Covid-19 mutations are the cause. At the end of 2019, the coronavirus was first detected in the Wuhan region of China before it migrated all over the world and transformed.

In the summer of 2020, a variant quickly becomes dominant, “D614G”, and infects a large part of the United States before hitting, among others, Brazil and Japan. In these countries, again studied, researchers find the same order of symptoms in cases of contamination as in Americans: cough then fever.

There is therefore no doubt for scientists: the order of symptoms would not be due to geographic, climatic, age, or even co-morbidities, but to “a mutation of a viral disease.” Right here, “the ‘D614G’ variant is more transmissible, because infected people are more likely to cough in public before being incapacitated by fever, explain the authors of the study.

To date, this is the only study on the subject. It is therefore difficult to generalize, especially since no data is yet available on other variants, such as Delta, which appeared in India, or Omicron, detected in South Africa. But it could be a lead on the progression of viruses.

Via This survey, scientists indicate that they want to encourage further research on this order of appearance of symptoms in infectious diseases. In fine, the aim is to better understand how variants affect the spread of viruses.