Elucidating the virological structure of influenza and its mutation mechanisms, Dr. Ahmadreza Mobin, infectious disease specialist and associate professor at Zanjan University of Medical Sciences, discussed the necessity of annual vaccine revisions and the prospects for developing long-lasting vaccines.

According to WebDA-Zanjan, speaking at a one-day scientific symposium on influenza held on Wednesday, November 4 (Aban 13, 1405), Dr. Mobin referred to the structure of the influenza virus and the role of its surface receptors, stating: “The virus utilizes a protein named ‘hemagglutinin’ to enter respiratory tract cells, and vaccines are likewise designed to prevent the virus from binding to cells.” He added: “Since segments of this protein undergo alterations every year—allowing the virus to evade detection by the immune system—the production of the influenza vaccine must also be reviewed annually.” Pointing out the differences between influenza types A and B, this infectious disease specialist noted that only a single subtype lineage of type B circulates, whereas type A exhibits a broader range of subtypes, with animals serving as its primary reservoir.

Dr. Mobin further explained the two principal mechanisms of viral variation as follows:

• Minor mutations (Antigenic drift): Lead to gradual immune evasion and seasonal epidemics.
• Major shifts (Antigenic shift): Occur during the reassortment of genomic segments within animal host cells, potentially generating entirely novel strains.

According to him, such fundamental alterations can lay the groundwork for global pandemics, although most mutations are doomed to extinction and only a small fraction persist.

He noted that global research centers monitor viral mutations at the end of each season and announce the strain to be incorporated into the following year’s vaccine accordingly; hence, vaccines produced across various countries contain identical active ingredients, with differences limited solely to manufacturing processes and production quality.Drawing upon the experience of the COVID-19 pandemic, the university’s associate professor emphasized that this event provided the courage and capability required to rethink vaccination approaches, raising the current question of whether a long-lasting vaccine targeting conserved regions of the virus can be designed to replace annual injections.

Regarding the seasonal cycle of the virus, he stated: “Following each epidemic, community immunity rises and infection rates decline; however, over several years and with the accumulation of mutations, the virus re-emerges, and at multi-year intervals, the likelihood of a completely novel strain appearing and triggering a fresh pandemic arises.” Dr. Mobin concluded by emphasizing that comprehending these mechanisms plays a pivotal role in preparing the health system and adopting appropriate preventive and therapeutic strategies.