Recurring weather plays an essential role in the subtleties of many infectious diseases. A researcher at the University of Federal Fluminense, reveals that seasonality considerably supports the transmission of Covid-19 and that the predicted seasonal weather for second wave will be autumn – winter pattern, the peak time of respiratory viral transmission. The research findings are published in the form of a preprint report on medRxiv, a pre-print journal.
Hence, these speculations disclose an integral information, crucial for public health officials to plan their actions to prevent the transmission of the novel coronavirus as well as the other respiratory viruses in future.
— medRxiv (@medrxivpreprint) September 3, 2020
Seasonality is a time series attribute, where data shows regular and predictable changes recurring every year. Any predictable fluctuations or a disease pattern recurring over a one-year period, almost at the same time of weather is supposed seasonal. Numerous infectious diseases, particularly viral infectious diseases with respiratory transmission are commonly observed to have a seasonal transmission pattern, speculated in the study. Therefore, author of the study, based on these previous literature, made an implication that there is a period of the year when the viral transmission rate as well as the prevalence of epidemic is significantly highest observed in this period relative to the complementary period of the year. This stands for pneumonia, Influenza viruses, cholera, rotavirus, dengue, measles, and other coronavirus viruses.
Marcio Watanabe, corresponding author of this quantitative study asserted that seasonality strongly contributes towards the Covid-19 transmission. She conducted the study to determine the cyclic period of the year, particularly responsible for Covid-19 transmission since its outbreak. The statistical algorithms are used to infer the statistical figures. The qualitative epidemic model, SEIR model, is used to determine the quantitative figures.
Statistical data reveals that seasonal period predicted for Covid-19 transmission is autumn/winter pattern with highest transmission rate in contrast to spring- summer when transmission is slower. It is believed that temperature has nothing to do with the transmission rates.
Study also elucidated the social distancing effect, catering the difference between the seasonal effect, the social distancing effect and the income effect. Study note that the months with the highest number of cases are reversed in the Northern and Southern hemispheres.
Therefore, Watanabe states that expected second wave will being around September or October in the Northern hemisphere. Relatively, a considerable reduction in transmission rates will be observed in Southern hemisphere in the same period.
The estimated seasonal periods occur between April – September, highest transmission rate season in the south and October – March, highest transmission rate season in the north. In Europe and Northern Hemisphere, it was found that first wave lasted mainly just two months or less, from mid-February to mid-April. Therefore, physical distancing interventions are crucial to be adopted for around two months before the seasonal period ends.
“With the seasonality effect taken into account, we predict that many (but not all) countries in the Northern hemisphere will have second waves which will begin more generally during September and will increase in October and November. In fact, at the end of August, the trend of increasing the number of cases in some countries in the Northern hemisphere restrictive social distancing measures such as lockdown maybe be not as good as it was in the first wave due to the length of the period high season will take its entire six-month span,” says Watanabe.