Banko: The speed of vaccination will determine the further course of the pandemic

The speed of vaccination will determine the further course of the pandemic, but also the evolutionary development of the coronavirus in the direction of further adaptation to easier transmission between people, said virologist Ana Banko.

She stated, as reported by AmCham, that because of this, it is a big challenge to control the spread of the pandemic while immunization is taking place at the same time.

"The current variability of the virus and the creation of new variants and strains, in the future, could affect the potential necessity for seasonal use of the vaccine, that is, the adaptation of the existing ones," said Banko.

She said that the principle of vaccine immunization is to prevent infection or alleviate the clinical course of the disease.

"In the simplest terms, our body needs to create antibodies specific to the protein of the virus responsible for its entry, i.e. binding to our cells. Thus, in every subsequent contact with the same virus, we will have a defense mechanism ready to prevent the attachment and entry of the virus," said Banko.

According to her, with a large number of pathogens, immunity created in this way can be lifelong, while with others, immunity is limited to one to several years.

"Viral vaccines that we know so far are based on attenuated, i.e. weakened virus, then inactivated, i.e. killed virus, but there are also subunit or protein vaccines that contain only the virus protein, responsible for binding to our cells," said Banko.

She stated that in the last two or three decades, vaccines have also been developed that allow the body to create the viral protein itself, thereby activating the immune system to produce antibodies.

"These are exactly the vaccines we have today, RNA and vaccines based on the adenovirus carrier principle," Banko said.

According to her, the vaccines registered against COVID-19 in the world so far and used in our region are based on three principles, two of which are even innovative.

She said that the Sinofarm vaccine was produced on the model of an inactivated virus, which means that the vaccine contains dead SARS-CoV-2.

"Well, it cannot multiply or cause disease, but our immune system recognizes it and makes antibodies. As the amount of virus in the vaccine is limited, adjuvants are added to them in order to maximize the immunogenicity of the vaccine," said Banko.

She said that RNA vaccines, such as Pfizer-Biontek and Moderna, have so far been developed in the field of oncology, but clinical studies were also conducted a few years ago on a viral RNA vaccine against rabies.

"Informative RNA is introduced with these vaccines, which is a short-term instruction for the machinery of our cells to make the S protein itself, and then antibodies. This overcomes the limitation of the amount of S protein in inactivated or subunit vaccines," said Banko.

According to her, due to instability, RNA vaccines require storage at extremely low temperatures, but their advantage lies in the simplicity of production and rapid modification of RNA in the event of the appearance of new strains, as well as new epidemics or pandemics with other viruses.

She said that the Sputnik V and AstraZeneca vaccines packed the information to synthesize the S protein into a dead adenovirus.

"So, the adenovirus is used as a carrier that ensures the safe entry of this information into our cell, and it cannot cause disease," said Banko.

As she said, the difference between the Sputnik V and AstraZeneca vaccines is that they use different adenoviruses as carriers.

"While Sputnik V uses two human adenoviruses, different for the first and second doses of the vaccine, AstraZeneca uses a chimpanzee adenovirus," Banko said.

She said that at this moment, all vaccines that are in mass use have passed strictly defined steps of preclinical and clinical trials.

"They have been tested on tens of thousands of volunteers, and the number of administered doses in the world has exceeded 250 million. "All these facts speak about the safety of vaccines, and we can assess the advantage of one over the other only based on the analysis of the results and effects of immunization for more than half a year," said Banko.

As she said, the limited availability of vaccines, due to higher demand than the objective production capacities, will not leave room for the majority of the world's population to choose the manufacturer.

"At this moment, it is impossible to estimate even a definite period after which we are immunized against COVID-19 with a vaccine. Based on what we know about natural COVID-19 infection, the period of immunization will last at least six months, but it is realistic to expect that it will last much longer," said Banko. According to her, only after the first groups of vaccinated people begin to lose their immunity, will the duration of immunity with the use of the vaccine be looked at.

"Simply measurable immune status can be checked by testing the blood antibody titer value, but immunity depends not only on this, but also on the potential of T memory immunity to restart the production of antibodies with each new encounter with the virus, even when their value in it is no longer measurable for our organism", said Banko.

She stated that this very fact gives hope that immunization after vaccination can last longer than one season.