RIO DE JANEIRO, BRAZIL – The third and last phase of the clinical trials of the Cuban vaccine candidate Soberana 02 against the coronavirus concludes this Wednesday, May 26, when all the volunteers participating in the tests are expected to have completed the immunization scheme.
Soberana 02 and Abdala -which already completed its phase 3 at the beginning of May- are the two most advanced of the five formulas Cuba is developing against Covid-19. If these studies prove their effectiveness, they will become the first vaccines developed in Latin America.
Confirmation of efficacy would also enable the island’s health authorities to obtain authorization for emergency use or pharmacological registration, something they hope to achieve in June.
These authorizations would make it possible to start mass vaccination in the Caribbean country, which is going through the worst moment of the pandemic, with a third wave of contagions which for weeks has not dropped below a thousand cases a day despite the restriction measures in force.
The Cuban government has insisted that it expects to have the entire population immunized before the end of the year.
TWO SCHEMES TO BE TESTED
In this third stage of trials, carried out in Havana with a double-blind and placebo group, the experimental vaccine has been administered to 44,010 volunteers aged 19 to 80 years with two immunization schemes: one with two doses of Soberana 02 and the other with two doses of Soberana 02 and a booster dose of Soberana Plus, another of the formulas under investigation.
Soberana 02 is a subunit conjugate vaccine -traditionally very safe- which combines the virus antigen and the tetanus toxoid (of attenuated or suppressed toxicity) and also uses aluminum hydroxide to stimulate the immune system response. It has been developed by the state-owned Finlay Vaccine Institute (IFV).
The director of Clinical Research of the IFV, Meiby Rodriguez, explained that once all the doses have been administered, the volunteers will be monitored to detect possible infections “as part of evaluating the efficacy variable, which is fundamental for the registration of the vaccine.”
The comparison of the number of infections among those who received the vaccine candidate and those who received placebo is the data that will reveal the percentage of efficacy of the formula.
GOOD PRELIMINARY DATA
Rodriguez, quoted by the state-owned Cuban News Agency, said that it had been found that those who received placebo in the first two phases of the clinical trials “were twice as likely to get sick as those who were vaccinated.”
According to preliminary data from those stages, 76% of the volunteers increased the concentration of specific antibodies against the SARS-CoV-2 virus after receiving two doses of Soberana 02, a percentage that rises to “around 90%” in the case of those who received the additional dose of Soberana Plus,” the scientist assured.
Cuba has also sent Iran 100,000 doses of this vaccine candidate to carry out a phase 3 study there, of which no information has been released so far.
The other more advanced formula, called Abdala and developed by the Center for Genetic Engineering and Biotechnology (CIGB), completed phase 3 clinical trials on May 1 with 48,000 volunteers from the capitals of the eastern provinces of Santiago de Cuba, Guantánamo, and Granma.
NO COVAX OR IMPORTED DOSES
In parallel to the traditional clinical trials, the health authorities have launched a massive health intervention study with Soberana 02 and Abdala in Havana and the eastern part of the island, the areas with the highest infection rates.
The formulas have already been inoculated in health personnel and those at risk and are expected to be administered to 1.7 of the 2.2 million inhabitants of the capital.
Cuban scientific institutions, which have long experience and proven results in the biotechnology sector, are also working on two other formulas: Soberana 01 (intramuscular) and Mambisa (intranasal), which are in the preliminary stages of evaluation.
Cuba is not part of the Covax Mechanism created by the World Health Organization for middle and low-income countries to access vaccines, nor has it purchased them on the international market.
Since the beginning of the pandemic and to date, the island has accumulated 136,628 positives to the coronavirus and 912 deaths.