The number of vaccinated people that Cuba shows today is due, to a large extent, to the implementation of health intervention in risk groups and territories; this process, because of the logistical complexity and the volume of the population to be immunized, has raised many questions in the population.
In this regard, doctors Sonia Resik Aguirre, principal investigator of the health intervention with the vaccine candidate Abdala and head of the Virology Department of the Pedro Kourí Institute of Tropical Medicine (IPK), and Belkis Galindo Santana, epidemiologist at the IPK and head of Surveillance of Adverse Events by the National Immunization Program.
When can the entire Cuban population be vaccinated?
Vaccination may be massive once the vaccine candidates obtain the authorization for emergency use or are registered by the Cuban regulatory authority, the Center for State Control of Medicines, Equipment and Medical Devices. From that moment on, it will be applied voluntarily to the entire Cuban population.
The emergency use authorization is requested once the results of the first interim report of the Phase III clinical trials have been obtained. If satisfactory evidence is obtained after the third report, candidates can be registered as vaccinations.
The difference between each report is determined by the number of people and the appearance of positive cases for SARS-CoV-2.
At this time, what is being carried out in the country is the process of health intervention in risk groups and territories, authorized by the Minister of Public Health based on the epidemiological situation and available technology, that is, the vaccine candidates with their evidence safety and immunogenicity in Phase I and II clinical trials.
What about those allergic to Thimerosal?
Those allergic to Thimerosal may be vaccinated at the end of the production of the batches without this compound. Someone may be allergic and not know it, because these processes occur at any time in life. If someone is allergic, they should not be vaccinated now and if the allergy manifests itself during the health intervention, they will receive the established treatment and will not be able to continue with the rest of the doses.
Thiomersal is a component that was previously used to heal wounds and is present in many of the Cuban vaccines. The fact that a person did not have an allergy previously does not mean that they do not have it later, hence the importance of maintaining vigilance during the hour following the vaccination and seeking medical help in case of any symptoms.
What will happen to the people who are excluded from the health intervention?
It depends on the cause that motivated the exclusion. If it is a momentary condition, you can receive the immunogen later, when registering as a vaccine.
However, if they are people with decompensated chronic diseases, immunodeficiencies or in treatments with cytostatics, they cannot be immunized.
Although, this population group will be protected by achieving high vaccination coverage and population immunity.
What type of adverse events have been identified with the application of Soberana 02 and Abdala?
Adverse events may be local or systemic and may or may not be related to vaccination, because everything that occurs after the application of the drug is considered an adverse event.
In both candidates, mild and local ones are more frequent, related to pain and redness at the injection site, and hardening of the area where the dose was administered; while among the systemic ones, drowsiness, decay, low-grade fever (moderate fever) and headache are reported. All are as expected after the administration of any vaccine.
In addition, high blood pressure figures (arterial hypertension) have been recorded, an unexpected adverse event, but which is not directly related to vaccine candidates, since in those who received placebo the increase in pressure was greater than in those immunized with Sovereign 02 plus Plus and Abdala.
The three doses of Abdala are applied with an interval of 14 days and Soberana 02 plus Plus 28 days apart. Why apply different schemes? Do they elicit a similar immunity?
Short and long schemes have been around forever. Lengths have been suggested to have the advantage that they better prepare the immune system to achieve a good response. In the case of Abdala, the short and long schemes were evaluated and the immune response was similar, so it was decided to adopt the first one given the complex epidemiological situation in the country, where it is convenient to achieve immunity more quickly.
As for Soberana 02, in the trials only the long scheme was evaluated and it worked very well.
The immunogenicity and safety results in clinical trials were very good in the two vaccine candidates.
How long does it take for the body to develop immunity to the virus?
For all the vaccines that are applied in the world against any disease, it takes the organism to develop the best immunity values between 14 and 21 days after the last dose is administered.
Not all vaccinated people - regardless of the disease - achieve that long-awaited immunity, because it depends on two factors: the immunogen and the individual's genetics, and there is no 100 percent effective vaccine.
The more people receive these drugs, the higher the vaccination coverage and the greater the effective immunity that will go from being individual to population or herd immunity. Similarly, the possibility of the disease occurring will decrease when high numbers of vaccinated are achieved in the country.
Until that time comes, it is necessary to continue using the nasobuco (sanitary mask) and maintain hygienic and distancing measures.
If a person gets sick, is it because the vaccine candidate was not effective?
The anti-COVID-19 vaccine candidates were designed so that people who become ill have mild symptoms and do not transition to severity. They were not created to interrupt the circulation of the virus, but the vaccination of the population is what will cut transmission.
Only when the Phase III clinical trials are concluded will we be able to talk about efficacy and then the post-licensing studies will come where the effectiveness will be determined in a general way and in specific groups, the long-term, rare and unexpected adverse events and it will be determined if they are maintains the immune response over time.
How does the health intervention tax the approval of the emergency use of vaccine candidates?
Health intervention and intervention studies are added values to clinical trials by increasing the data needed by vaccine candidates for registration. Likewise, they consolidate the efficacy results, taking into account that they are less controlled than Phase III, and in this way the population is protected.
Can SARS-CoV-2 genetic variants influence the efficacy of these immunogens?
SARS-CoV-2 is an RNA virus and like the rest of these viruses it is common for it to mutate, as has happened with HIV and H1N1 influenza. When they are said to be new variants, it is because they have changes in amino acids and so far they have shown greater transmissibility and pathogenicity.
Currently, it is under study whether the vaccines approved in the world maintain their effectiveness in the face of these modifications and in the case of Cuban vaccine candidates, research is also being carried out on the production of antigens against these variants. The potentialities of our technological platforms allow us to improve the recombinant protein quickly so that it is more effective against mutations.
However, if the vaccinated decrease the antibody titers - which will never reach zero - due to the genetic variants, the individual will always be more protected against the transformations of the virus than the non-immunized one.
What is the treatment for volunteers who later test positive for the virus?
All people are followed up, mainly those participating in the Phase III clinical trial, to determine if the vaccine candidate caused a decrease in symptoms and severity.
Hospital facilities, whether they are intended to serve Phase III volunteers as well as the rest of those immunized, have the action protocols established to assist each patient with COVID-19.
Will those people who did not complete the immunization schedule and tested positive be vaccinated later?With which vaccine candidate?
If they did not develop sufficient antibody titers, they will later be immunized with one of the vaccine candidates intended for convalescents.
The health intervention process continues to advance successfully throughout the national territory. Today, June 10, began in the head municipality of the province of Santiago de Cuba what will improve the epidemiological situation of the territory.
The Minister of Public Health, Dr. José Angel Portal Miranda recalled in previous days the importance of maintaining sanitary measures to achieve the success of this process:
"In the midst of the complex actions that are carried out to guarantee health intervention, the discipline and responsibility with which it is assumed by both the Health personnel in charge of carrying it out, as well as the population that decides to be part of it, are essential."