Research into the development of vaccines against SARS-CoV-2, which causes COVID-19, continues, so private laboratories, public institutions and non-profit organizations join forces to make more potent inoculants, which reduce the risk, especially, of hospitalizations and deaths.
As demonstrated over the months after the start of vaccination, the immunological memory and protection of vaccines decreases over time, and although it depends on each human being, it has been established that in approximately six months there is a drop, which is why the booster or a third dose of the vaccine rescues and recovers the state of protection against coronavirus.
A new study carried out by the Chinese laboratory CansinoBio with its Convidecia™ vaccine showed advantages as a heterologous enhancer (combination of available vaccine platforms) over Ómicron, as reported by the pharmaceutical company.
The CanSino Biologics vaccine developed in China, which comes in a single dose, is already authorized for emergency use in Argentina, Chile, Ecuador, Hungary, Indonesia, Malaysia, Mexico, Moldova and Pakistan.
The vaccine was developed by CanSino Biologics in collaboration with the Beijing Institute of Biotechnology. This is a single-dose viral vector vaccine that can be stored between 2 and 8 degrees Celsius. Viral vector vaccines use a virus other than SARS-CoV-2, such as an adenovirus, genetically modified that cannot cause the disease, but can produce proteins from that coronavirus to generate a safe immune response.
According to information released by the laboratory, the CansinoBio vaccine in its two versions, injectable and inhalable, “can induce a stronger immune response than inactivated recombinant protein injections”. Protein-based vaccines use harmless fragments of proteins or protein structures that mimic the virus that causes COVID-19, in order to generate an immune response.
“The neutralizing antibody response generated by the CanSino Inhalable vaccine booster against Ómicron is 14.1 times greater than, for example, that of the Sinovac booster and twice as high as the same injection of CanSino intramuscular,” the study added. Both Sinovac and Sinopharm, which is applied in Argentina, are developed with inactivated or attenuated viruses, which use the previously inactivated or attenuated SARS-CoV-2 virus, so that it does not cause the disease, but does generate an immune response.
The results are based on a study involving 904 volunteers who had received two doses of inactivated vaccines six months earlier, the laboratory said.
The study was published by CanSino Biologics Inc. on MedRXIV, the renowned prepress platform for biomedical preliminary research where it gave details of “the efficacy of its recombinant vaccine for COVID-19 (“Ad5-nCoV”, trade name: Convidecia™) as a heterologous booster against the Ómicron variant,” he reported.
“The results showed that booster vaccination with the intramuscular injection or the inhaled version of Convidecia™ generated greater neutralizing antibody responses than those induced by the homologous inactivated vaccine boost or the heterologous recombinant protein vaccine booster. A heterologous booster with one dose of Convidecia™ can significantly increase cellular immune protection against transmission and infection of the Omicron variant, and effectively prevent severe cases and immune escape,” stressed the study, which has not yet been peer-reviewed.
As mentioned, the study was “open and controlled in parallel with the participation of 904 volunteers vaccinated with two doses of inactivated vaccines six months earlier”. Volunteers “were randomly assigned to four groups to receive one of the following boosters: one dose of Convidecia™ by intramuscular injection, one dose of the inhaled version of Convidecia™ (a fifth dose compared to intramuscular injection), one dose of recombinant protein subunit vaccine and one dose of vaccine inactivated”.
“The study showed that boosting with the intramuscular or inhaled version of Convidecia™ can generate significantly higher RBD-specific binding antibodies than those induced by the recombinant protein vaccine or the inactivated vaccine. 14 days after the booster vaccination, the participants' RBD-specific antibody levels were 523 (IQR, 137-1336) for the inhalation Convidence™ group and 464 (IQR, 210-1097) for the intramuscular Convidence™ group. The results were significantly higher than the RBD-specific antibody levels of 174 (IQR, 58-488) for the group that received the recombinant protein vaccine and 61 (IQR, 30-124) for the inactivated vaccine group,” he stressed.
The authors of the study detailed that “an increased neutralizing antibody response against the wild SARS-CoV-2 virus induced by the inhaled version of Convidecia™” was observed. In this regard, he specified that on day 28 after the booster vaccination, “the study showed an increase in the mean geometric titer (“GMT”) of 874 (95% CI = 569-1342) for the inhalation Convidence™ group, 628 (95% CI = 455-868) for the group Convidecia™ by intramuscular injection, while the GMTs of the groups of protein vaccine recombinant and inactivated vaccine decreased to 210 (95% CI = 137-321) and 69 (95% CI = 51-93), respectively.”
“Importantly, Convidencia™ also demonstrated proven protection against the Ómicron variant. Both groups that received Convidecia™ as a booster exhibited significantly higher immune responses, with a GMT of 320 (95% CI = 191-538) for the inhaled group and a GMT of 261 (95% CI = 178-382) for the intramuscular group 14 days after the booster vaccination. In comparison, the GMT results of the recombinant protein vaccine and inactivated vaccine groups were 86 (95% CI = 59-127) and 54 (95% CI = 42-71), respectively.”
Regarding the cellular immunity response, according to the Chinese laboratory, its vaccine also obtained a broadly favorable response because “the administration of Convidecia™ as a heterologous booster can significantly induce cellular immune responses. In particular, the inhaled version of Convidence™ induced the strongest IFN-γ response among the four study groups, at 100% (95% CI, 92.6%-100.0%) and 95.7% (95% CI, 85.2% -99.5%) at day 14 and 28 after booster vaccination, respectively. The results were higher than those of the intramuscular Convidence™ group, which were 85.4% (95% CI, 72.2% -93.9%) and 68.8% (95% CI, 53.7% -81.3%), respectively.”
Overall, this latest study showed that “administration of CansinoBio Convidecia™ as a heterologous booster can induce a stronger immune response than recombinant protein and inactivated vaccines”, as it showed that it stimulates “a greater humoral immune response and irrespective of the route of administration”. According to the authors, “the inhaled version of Convidecia™ provides a more effective and efficient alternative to the booster vaccination program, as it can also induce mucosal immunity to achieve triple protection with only the fifth dose of an injectable version of Convidecia™.”
CansinoBio, founded in 2009, is a laboratory dedicated to the research, production and marketing of innovative vaccines.
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