Abdala is a subunit vaccine, developed for vaccination against the SARS-CoV-2 virus. As active pharmaceutical ingredient it contains the receptor-binding domain (RBD) and as inactive ingredients it contains phosphate salts and aluminum hydroxide gel adjuvant. It is manufactured in the Center for Genetic Engineering and Biotechnology (Havana, Cuba), with a production system of more than twenty years of experience, complying with current good production practices and in accordance with the recommendations of the World Health Organization ( WHO).
In clinical studies, the effectiveness of a vaccine is measured. They are controlled studies, under slightly more ideal conditions. They are used to check if the vaccine, in addition to being safe, provides levels of protection. Clinical studies are carried out under ideal conditions and are designed to evaluate the vaccine preparation under conditions with strict inclusion and exclusion criteria, which means that people are included for almost ideal conditions of immunocompetence, age, biochemical and hemochemical parameters, because, for the first time, the product is going to be evaluated, and that is why placebos groups are used.
The efficacy of Abdala (92.8%) is to prevent the symptomatic disease: covid-19. Vaccines prevent, in a percentage, that the person is infected; in another percentage, they prevent the person from becoming ill, from reaching seriousness or a critical or serious state of the disease; and in another percentage, they prevent the person from dying. In clinical studies, Abdala was 100% effective in preventing death; 100% efficient to get to gravity; and a lower percentage (92.8%) to avoid symptomatic disease.
When a vaccine begins to be used massively, then you have to measure its effectiveness, which is measured in real life and is a different term. In general, the effectiveness values are lower than those obtained in clinical trials. That is, effectiveness is measured when a vaccine is applied in real life conditions, in the field, and is administered to everyone who needs to be vaccinated from 19 years of age. In the population there may be people with greater or lesser immune competence. In fact, vaccinations from the most vulnerable groups are favored, because they are precisely the groups where there may be a higher incidence of severe disease and mortality may be higher. Vaccination is started for these people, even if they are the individuals who have a less powerful immune response, but even so the vaccination will favor them and better prepare them for infection with the virus. In fact, in the case of the most massive use of the vaccine, we have used it in the intervention study that was carried out on BioCubafarma medical personnel and health personnel; then, in the sanitary intervention, and later, as of July 9, in the massive vaccination. But, based on the results obtained, specific risk groups were also vaccinated, such as nephropathy patients and also pregnant and lactating mothers.
The Abdala vaccine effectiveness study is ongoing. This study involves collecting data from all the municipalities of Cuba, which covers a universe of more than 300,000 people. That is, the clinical study is scaled from 30,000 – 40,000 to 300,000 or more subjects. This, in addition, has a scientific methodology, it is necessary to fill in the databases in all the vaccinated municipalities; of those vaccinated, know how many doses they received; of those not vaccinated, why they were not vaccinated, and then calculate and control the statistics to obtain the effectiveness data. It also goes through registering all the people who had a positive SARS-CoV-2, and how they evolved. At the moment, the data is being collected, in order to make it known as one more scientific study.
Abdala is administered intramuscularly in a short or accelerated schedule of three doses separated by 14-day intervals (0-14-28 days).
Vaccinating the Cuban pediatric population is an objective of our vaccines and for this we have been developing the Ismaelillo trial, with the Abdala vaccine. In that study, two strengths or concentrations have been evaluated. The vaccine in adults has 50 micrograms, and in children we are evaluating 25 and 50 micrograms, since the immune response of children should almost always be higher and more homogeneous than when speaking of an open adult population, which is very large, of 19 years old and more. Vaccination of the pediatric population is essential. As time passes, more adults will be vaccinated, and it is highly probable, and some indications are already being seen, that the highest number of infected is precisely in these unvaccinated populations. In addition, we would like to vaccinate our children as soon as possible so that they can go to schools and parks.
Mambisa is a formulation with two proteins, which are two antigens obtained through recombinant DNA techniques. Protein subunit vaccines are very safe. They are very innocuous formulations and do not have any possibility of causing infection, since they are part of the most important protein of the virus, obtained by means of recombinant DNA techniques, purified to high levels of purity. In addition, they are technologies that allow them to be combined with each other and with other more complex technologies.
Mambisa combines two antigens: that of the nucleocapsid of the hepatitis B virus, extensively studied at the CIGB, which has the ability to stimulate the immune response at the mucosal level and in the systemic compartment, bound to the RBD antigen which is Abdala . It is applied intranasally.
This route of administration was chosen because the virus penetrates mainly through the nostrils, and in these compartments there is an immune system. In the mucosa, immunoglobulins of the IgA type are generally activated. When it comes to measuring antibodies, we almost always talk about IgG immunoglobulins, which are of the systemic class and are stimulated when vaccinated intramuscularly. The immunological memory in this case is of cells that, when faced with a new antigen, will awaken IgG type antibodies.
If you are vaccinated intranasally, there will be another type of immunoglobulins, which are IgA, and even IgA are present in the mucosa, forming a dimer, which expresses a higher inhibition and neutralization capacity. Systemically they are also present, but in monomeric form. Intranasal vaccination is thought to provide a barrier to infection, prevent virus replication, and decrease viral shedding.
A phase I / II clinical trial is currently underway with the Abdala vaccine (intramuscular administration) and the Mambisa vaccine candidate (nasal administration), for the reinforcement of immunity in convalescent subjects of the viral disease covid-19. The approved study includes subjects aged 19 to 80 years, convalescing from the disease, with at least 2 months after being discharged. The Cuban regulatory authority, the Center for State Control of Medicines, Medical Equipment and Devices (CECMED) will verify compliance with good clinical practices, according to the verification programs established by the authority as part of its regulatory and oversight mission.