Despite the fact that in most regions of Europe the incidence is declining, there is no need to talk about the final victory over the virus. Every day, hundreds of thousands of cases of Covid-19 infection are recorded in the world, and several thousands of the sick die. In total, more than 17 million people worldwide have contracted coronavirus infection, and the number of Covid-19 victims has exceeded 660 thousand. Of course, this applies to all young volunteers in Europe. Because we must be in solidarity with all people and countries against the virus.
In some European countries, where the introduction of restrictive measures has made it possible to stop the spread of infection and reduce the number of cases to a minimum, an increase in the incidence is observed again. This situation has developed, for example, in Poland, where by mid-May the number of cases had reached a minimum and did not exceed 20-30 per day, but now there are more than 1,500 cases of Covid-19 every day. A similar picture is observed in Sweden, Ukraine and Portugal. Restrictive measures are still in force in many European countries and the virus has not been defeated. Meanwhile, scientists fear that this fall, the world's population will face a second wave of coronavirus infection.
How to recognize the second wave?
There is no clear definition of the second wave. In general, the second wave is characterized by a repeated steady increase in the number of cases soon after the recorded decline, but scientists interpret this concept in different ways - each in its own way. If the number of infected is growing, then decreasing, and there is no steady increase in cases of infection, then we are not talking about the second wave - these fluctuations occur within the first wave of infection.
Is the Spanish flu experience useful?
The Covid-19 pandemic, already at the initial stages of its spread, was compared with the Spanish flu, which in 1918-1919 infected more than 500 million people - a third of the world population. The number of victims of the epidemic, according to rough estimates, was 20-50 million, and possibly more. The exact number of people who died from the Spanish flu is not known - at that time in different countries, residents also died from hunger, other infectious diseases, as well as during hostilities and conflicts. Due to the lack of detailed registers where the cause of death is indicated, the number of victims of the Spanish flu to date has been estimated only approximately.
It is believed that the Spanish flu spread in waves - some time after a significant decrease in the number of infected, a sharp increase in the incidence began. The first wave, which ended in August 1918, began in the spring of 1918, and the second and third, which turned out to be much more deadly, replaced it in the fall of 1918 and in the winter of 1919, respectively.
Why didn't the virus disappear in the summer, as many expected?
Back in March, when the virus began to spread rapidly outside of China, it was suggested that by summer, with the onset of warm weather, the activity of the virus will decline, and closer to autumn, it will probably begin to increase again.
To some extent, temperature can indeed affect the survival of the virus. However, there is evidence that temperature change is not able to seriously affect the spread of the virus, and SARs-CoV-2 itself is not seasonal.
Against seasonality, the fact that close relatives of the SARs-CoV-2 coronavirus - the viruses that caused atypical pneumonia (SARS) and the Middle East respiratory syndrome (MERS) - spread regardless of the season and air temperature, and MERS-CoV still rarely found in the Middle East, where it is always hot.