Three waves changes, new variant strains, and vaccination effect against COVID-19 pandemic

It has been more than one year since the first case of the coronaviruses was infected by COVID-19 in China. The world witnessed three waves of the corona virus till now, and more upcoming is expected, whereas several challenges are presented. Empirical data displayed that the features of the virus effects do vary between the three periods. The severity of the disease, differences in symptoms, attitudes of the people have been reported, although the comparative characteristics of the three waves still keep essentially indefinite. In contrast, the sense of danger toward the cries gradually decreases in most countries. This may be due to some factors, including the approved vaccines, introducing alternative plans from politicians to control and deal with the epidemic, and decreasing the mortality rates. However, the alarm voice started to rise again with the appearance of new variant strains with several mutations in the virus. Several more questions began to be asked without sufficient answers. Mutations in COVID-19 have introduced an extreme challenge in preventing and treating SARS-COV-2. The essential feature for mutations is producing new variants known by high tensmibility, disturbing the viral fitness, and enhancing the virus replication. One of the variants that has emerged recently is the Delta variant (B.1.617.2), which was firstly detected in India. In November 2021, a more ferocious mutant appeared in South Africa, also called omicron (B.1.1.529). These mutants grabbed world attention because of their higher transmissibility than the progenitor variants and spread rapidly. Several information about the virus are still confusing and remains secret. There are eight approved vaccines in the market; however, the investigation race about their effect against reinfection and their role against the new variants is still under investigation. Furthermore, this is the first time vaccinating against COVID-19, so the question remains: Will we need an annual dose of the corona vaccines, and the side effects don't been observed till now?