With Risk of Reinfection Is COVID-19 Here to Stay?

摘要

Many factors have served the swift transformation of the coronavirus disease (COVID-19) from an endemic to a pandemic. Some can be attributed to characteristics of the virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), such as high basic reproducing number (R ) of about 2 to 6 and transmissibility despite absence of clinical manifestations. However, our assumptions about the pandemic, most of which are falsified or questioned, at this point, also played a major role. One such assumption was that SARS-CoV-2, similar to H1N1 virus, will attenuate in high temperatures, while we are now observing the second wave of the pandemic in some countries, despite rising temperatures. Another assumption was reaching herd immunity for SARS-CoV-2 as the number of the affected individuals would rise, thus restrict the transmission of virus due to the increased number of immune hosts and decreased number of susceptible ones. However, a key concept in establishing and maintaining herd immunity is a strong immunization against the pathogens which lasts long enough so that the fraction of the population immune to the virus surpasses the herd immunity threshold. Therefore, persistence of immunoglobulin concentrations is one of the factors that determines the possibility of reaching herd immunity or periodic outbreaks.