The Cuban strategy for the development of vaccines against covid-19 continues to advance

Cuba designed its own strategy to achieve safe and effective vaccines against COVID-19.

As a result, the Emergency Use Authorization (EUA) was obtained for three of the five vaccine candidates. The Soberana-02, Soberana Plus and Abdala vaccines were used in the mass vaccination of our population from two years of age.

Cuban vaccines have made it possible to control the Covid-19 pandemic in our country. When 60% immunization of the population was reached, the cases infected with the SARS-CoV-2 virus began to decrease significantly. As of October 2021, Cuba was once again among the countries with the lowest incidence rate of Covid-19 in the world.

The arrival of the Ómicron variant, the most transmissible to date, caused the highest peaks in infections worldwide, surpassing previous waves. However, in Cuba the same did not happen. The effectiveness of the vaccines and the vaccination strategy have had to do with this behaviour. We have analyzed five factors that can explain the difference between what happened in Cuba and the world average data:

At the time that Ómicron arrived in our country, there was a level of immunity in the population close to 90%, between those vaccinated and people who had been infected.

Unlike other countries that also had high levels of immunity, vaccination in Cuba was more recent.

In Cuba, from the beginning, the immunization scheme with three doses was conceived. The importance of a third dose in the maturation of the response has been confirmed, not only in the amount of antibodies, but also in their neutralizing capacity.

Mass vaccination of the pediatric population two years of age and older has been another key and distinguishing factor of what has been done in Cuba, unlike the rest of the world.

Given the spread of the new supertransmitter strain, Ómicron, MINSAP made the decision to accelerate the application of an additional dose, so that, in the month of January 2022, in Cuba about 50% of the population had a dose of reinforcement.

The combination of these factors justifies the difference in the behavior of the pandemic in Cuba compared to the world, related to the Omicron variant.

Although the current situation of the pandemic is different from that of a few months ago, in terms of the level of infections, hospitalizations and death, the pandemic is not yet over as variants continue to appear, so the risk remains.

Derived from Omicron, new sub-variants have emerged such as Deltacron, which is a combination of Delta and Omicron. Also, as a product of the recombination of Ómicron BA.1 and BA.2, the sub-variant XE appeared. More recently, two other sub-variants have been reported, BA.4 and BA.5. The new sub-variants are closely watched by the World Health Organization (WHO). Although there is not enough data yet, it is thought that these sub-variants could increase the level of leakage to current vaccines.

Given the current scenario, together with the MINSAP, it has been agreed to take the following steps:

Make an evaluation of the immunity status of the Cuban population after 5 months of applying the booster dose. The study is ongoing and preliminary results are showing that a high level of antibody titers is maintained in most people. Only in people over 60 years of age and with chronic diseases is there a tendency to have lower titers. Although they are still very preliminary results, they have been taken into account, along with other elements, to approve the application of a fifth dose to this segment of the population. The application of the additional booster dose will begin in the month of May and the Abdala and Soberana vaccines will be used.

Administration of a booster dose to the population between 12 and 18 years of age who are already reaching 6 months after the first vaccination has also been considered. For this, the Sovereign Plus vaccine will be used.

Based on the results that demonstrate the safety of the vaccines in the pediatric population, the possibility of extending the EUA of Cuban vaccines for children under two years of age up to one year of age is being evaluated. In this sense, the MINSAP approved to start its use in two provinces of the country, Cienfuegos and Camagüey, one with the Soberana 02-Soberana plus vaccines and another with Abdala, respectively. In a first stage, active surveillance will be carried out to evaluate adverse events, before moving on to a phase of massive application throughout the country.

In parallel, clinical studies will be carried out in children between 6 and 11 months of age. The studies will be carried out with the Abdala vaccines and the Soberana 02-Soberana plus combination. The safe nature of our vaccines allows it and we consider it necessary to be prepared for the evolution that the SARS-CoV-2 virus may have.
As part of the strategy, we plan to continue advancing in the development of Soberana 01 and Mambisa to achieve the AUE of these vaccine candidates. The results are already being processed, we can anticipate that they are positive and that they can justify an authorization to be used as a booster dose. So, the 5 initial vaccine candidates could be turned into vaccines.

In the case of the Abdala, Soberana 02 and Soberana Plus vaccines, the information is being completed to present the request for a definitive sanitary registry to the CECMED, the results support it and we think it could happen in the not too distant future.

Progress is also being made in reaching recognition by the WHO of Cuban vaccines. Abdala began the process in March. The WHO accepted the expression of interest, which is what they call it, and the dossier is ready when they tell us that we must send it. It is a process that has its methodological steps that are being fulfilled.

In the case of Soberana 02 and Soberana Plus, the dossier for the WHO is in the preparation phase and once it is ready, the Finlay Vaccine Institute will contact the WHO to start the process.

To date, a little more than 80 million doses of vaccines have been manufactured and used in Cuba and 8 other countries.

Abdala’s production is being transferred to the new plant in Mariel. Validation and adjustment processes continue to be carried out. In the coming months this vaccine will be produced entirely in those facilities.

Another line of work in which we have advanced is the updating of vaccines with the Omicron strain antigen. This variant has been imposed in the world and is the one with the largest circulation today. It is likely that a strain will emerge that escapes the immunity induced by current vaccines. Taking this scenario into account, we are intensifying the development of vaccines with the Omicron variant RBD antigen. We think that we are close to having this vaccine candidate to initially evaluate it in animal models and later carry out clinical trials in humans.

Finally, we want to inform you that we are working on new generations of vaccines against the SARS-CoV-2 virus that allow greater effectiveness in cutting transmission.

Due to the unpredictable evolution that this virus could have, we must be prepared and continue working to face new challenges. In Cuba we continue to advance in the strategy to confront the Covid-19 pandemic.