The head of the Clinical studies, Epidemiology, and Biostatistics Research group of the Pasteur Institute of Iran explained the results of the further evaluations of the "PastoCovac" vaccine. In this regard, she maintained that the effectiveness of COVID-19 vaccines produced by the Pasteur Institute of Iran in collaboration with Finlay Institute of Cuba as booster doses is significantly higher than Sinopharm and AstraZeneca booster shots in immune response induction.

Dr. Amitis Ramezani emphasized that Pasteur Institute of Iran has played a crucial role in the control of infectious diseases, including rabies, plague, cholera, tuberculosis, relapsing fevers, malaria, and hepatitis in the country for more than 100 years, and also added since COVID-19 pandemic occurred experts and specialists of the institute have played important roles in identifying and controlling the infection by conducting follow-up studies. These activities have included the launch of molecular detection laboratory network for the SARS-CoV-2 virus, preclinical, and clinical studies of the PastoCovac vaccine and its production as well as providing diagnostic and treatment services to the patients.

Moreover, conducting studies on the design and production of a vaccine against the COVID-19 disease have been carried out extensively at this institute, and its supporting studies are also being implemented. Hitherto, 18 articles regarding different phases of PastoCovac (Soberana) development and clinical studies have been published by Iranian and Cuban teams.

 

The advantages of the PastoCovac vaccine

Dr. Ramazani, the infectious disease specialist at Pasteur Institute of Iran, meanwhile, emphasized that Soberana 2 and Soberana Plus vaccines have been developed and produced at Finlay Institute of Cuba and are manufactured under the names of PastoCovac and PastoCovac Plus at Pasteur Institute of Iran after the successful technology transfer. Soberana 2 (PastoCovac) has been approved for injection in Iran, Cuba, Belarus, Mexico, Nicaragua, and Venezuela.

From another point of view, she also put forward that PastoCovac is a vaccine based on recombinant protein. In the beginning of the COVID-19 pandemic, the country faced the challenge of providing vaccines. The potential advantage of this vaccine is in being relatively affordable, fast production, and also its stability at 2-8°C providing a good competitive advantage for this vaccine in addition to its high efficacy and safety. Fortunately, according to the studies, the license to use this vaccine as a booster dose was approved for all vaccine types in the country and this vaccine can be administered to 5- to 18-year-old individuals in addition to adults in Iran.

The member of the scientific staff of the Pasteur Institute of Iran continued “the mentioned vaccines are designed based on the subunit protein technology and with the advantage of conjugated vaccine technology, which has a high level of immunogenicity and very few side effects compared to other vaccines.

 

High efficacy of PastoCovac

Dr. Ramezani furthermore stated that phase 3 of the clinical trial of these vaccines was conducted to investigate the efficacy, safety, and immunogenicity in the population of 18 to 80 years under the supervision of the Food and Drug Administration on a population of about 24,000 people in Iran. The results of the study are published in the JAMA Network Open Journal and displayed that the injection of PastoCovac vaccine has a good ability to prevent symptomatic infection of COVID-19 disease as well as its severe forms. In the three-dose regimen, the efficacy of the vaccine in the prevention of symptomatic forms of the disease was about 65% and was also 97% effective in preventing hospitalization and severe forms of the disease, which is very reliable and appropriate. At the same time, the safety of this vaccine has been shown in this study.

In the beginning of the national vaccination program, a significant percentage of people received vaccines based on inactive virus-based platforms (such as Sinopharm and Bharat) or based on adenovirus (AstraZeneca) and the injection of booster vaccines was recommended due to the persistence of COVID-19 pandemic. Taking this into account, the immunogenicity and safety of PastoCovac vaccine as a booster dose for these people was also investigated. Based on this, the immunogenicity and safety evaluation of PastoCovac plus vaccine as a booster dose in people who had previously received two doses of Bharat vaccine as well as people who had received two doses of AstraZeneca or Sinopharm vaccine were carried out by the researchers of Pasteur Institute of Iran.

In a study conducted on people receiving two doses of the Bharat vaccine, it was shown that a percentage of these people did not have protective antibodies against COVID-19 infection three months after the second dose. Dr. Ramezani emphasized the injection of the COVID-19 vaccine produced by the Pasteur Institute of Iran in people who lacked sufficient antibody titer or had lost it, led to a significant increment in anti-spike antibodies as well as neutralizing antibodies. This study proved that PastoCovac plus vaccine as a protein-based vaccine can induce effective antibodies against SARS-CoV-2 in people vaccinated with two doses of inactivated virus-based vaccine.

According to the data obtained in this study, a high power in humoral immune responses induction in terms of neutralizing antibodies and anti-spike antibodies was observed in the recipients of this vaccine. The results of this study showed that pain at the injection site and weakness were the most common side effects after receiving PastoCovac plus vaccine. It has also been shown that the effectiveness of the booster dose of PastoCovac and PastoCovac plus vaccines is the same, and no specific side effects have been reported following their injection.

The head of Clinical Research, Epidemiology and Biostatistics Department of Pasteur Institute of Iran emphasized stated “in  another study, vaccinated individuals with AstraZeneca and Sinopharm vaccines were investigated”; these  people were divided into groups based on receiving different booster doses, including recipients of three doses of AstraZeneca, two doses of AstraZeneca and one dose of PastoCovac Plus, three doses of Sinopharm and two doses of Sinopharm and one dose of Pastocovac Plus. She mentioned that the purpose of this study was to compare two different vaccination strategies to find out how the booster dose of a different type differs in terms of immunogenicity and safety from the same doses of the primary vaccine. The results of this study indicated that PastoCovac Plus increased the level of anti-spike antibodies as well as neutralizing antibodies in both groups (people who received AstraZeneca or Sinopharm for primary vaccination). This increase was significant compared to the same type of booster dose, and it also resulted in fewer side effects than that of AstraZeneca vaccine.

The comparison of the immunogenicity of PastoCovac and PastoCovac Plus as booster doses in people immunized with two doses of Sinopharm vaccine showed high potency in generating anti-spike and neutralizing antibodies which were similar between both groups with good stability up to six months after injection. The findings of this study have been published in the Scientific Reports journal, which is one of the journals of the Nature subgroup.

 

Neutralization potency of the vaccine against the Omicron variant

This specialist in infectious diseases and tropical medicine continued” antibodies in the serum of vaccinated individuals (with two doses of Sinopharm, Bharat and AstraZeneca vaccines) who received a PastoCovac Plus booster dose, were also examined in terms of their ability to neutralize Omicron variant; the immunized people with PastoCovac Plus had a high ability to neutralize the virus”.

 

Persistence of immunity induced by PastoCovac vaccines

Dr. Ramezani meanwhile added the results of the evaluation of the stability of the immunity obtained from PastoCovac/Plus vaccines in people who had received three doses of these vaccines have shown that six months after the injection of the third dose, an acceptable immune response was still maintained in the recipients. In another paper published by the team of the Clinical Research and Epidemiology Department of the Pasteur Institute of Iran, in Pathogens and Disease Journal, the long-term adverse events of COVID-19 vaccines were investigated in the recipients of the standard vaccine regimen and combined regimens of Sinopharm and AstraZeneca in a period of 18 months. The results of the study have shown that the possible side effects caused by the vaccine are very low.

These studies have proved that the effectiveness of the COVID-19 vaccines produced by Pasteur Institute of Iran in collaboration with Finlay Institute of Cuba as a booster dose in stimulating the immune system was significantly higher than those of Sinopharm and AstraZeneca. Additional studies on the recipients of the COVID-19 vaccines are being conducted at the Pasteur Institute of Iran. Evaluating the possible side effects of the vaccines in the long term, identifying and investigating their effectiveness and side effects in people with underlying diseases are also aimed so that the researchers of this institute can take an effective step in collecting reliable and practical data as well as requirements of the people.