WHAT DOES SEASONALITY OF A VIRUS MEAN?
We are all familiar with viruses that routinely circulate, such as influenza, the common cold and chickenpox, which is caused by the varicella-zoster virus, VZV. These viruses are ‘endemic’, which means they are regularly found among particular people, or in a certain area. Some of them, such as VZV, circulate all year round, while others, such as influenza, cause more infections in the winter. We say that these virus infections show ‘seasonality’.
In some seasons, the peaks become so high that they are called ‘epidemics’, meaning a widespread occurrence of an infectious disease in a community at a particular time. COVID-19 is not yet endemic – having only emerged last year. However, it is an epidemic, in that it is still spreading rapidly.…
