Covid-19: virus likely to become seasonal
The new coronavirus Sars-CoV-2 could soon circulate seasonally, like the flu virus or other coronaviruses.
Colds, flu, bronchiolitis or even gastroenteritis are the so-called seasonal diseases: there are seasons and times of the year that are more favorable for their spread. In a scientific article published in the specialized journal Frontiers in Public Health, Qatari and Lebanese researchers believe that Covid-19, a disease caused by the current Sars-CoV-2 coronavirus, should also become seasonal at some time.
The coronavirus "will continue to cause epidemics throughout the year, until herd immunity is achieved," said Dr. Hassan Zaraket of the American University of Beirut, a co-author of the study. "That is why the population must learn to live with it and continue to apply preventive measures, such as the use of masks, physical distancing, hand hygiene and avoid meetings," he warned.
For his part, Dr. Hadi Yassine, from the University of Qatar, said there could be several waves of Covid-19 epidemics before herd (or group) immunity, or an effective vaccine, is achieved.
In the temperate regions of the world in particular, many respiratory viruses follow seasonal patterns. Influenza and several mild coronaviruses thus have a maximum incidence in winter in our temperate climate regions, while they circulate throughout the year in tropical regions, however, with more cases during the rainy season. Here, the researchers examined in detail the viral and host factors that control this seasonality, and reviewed the latest knowledge on the transmission and stability of the current coronavirus.
The authors explain that the survival of a virus in the air and on surfaces, the populations susceptibility to infection, and human behavior (such as clustering indoors) are factors that differ seasonally and influence the transmission of respiratory viruses.
But where influenza, seasonal viruses and Sars-CoV-2 stand out is in the transmission rate, the famous R0. That of the current coronavirus is much higher than that of the flu, mainly because the population is not yet immune. Once herd immunity, or a large vaccination campaign, has been achieved, this R0 is expected to decrease and make the coronavirus more sensitive to seasonal variations.
"This is a new virus and although scientific knowledge is increasing, there is still much that is unknown. We will see if our predictions turn out to be true or not in the future. But we think it is very likely, given what we know so far, that Covid -19 eventually becomes a seasonal illness like other coronaviruses", concluded Dr. Zaraket.