Thousands of COVID-19 infections and at least 12 deaths among infants, small children and adolescents in Cuba prompted authorities to start vaccinating children as young as age 2 this week, relying on limited clinical data on the efficacy of a local product tested on 350 minors.
“The number of coronavirus infections happening in Cuba in recent months in the pediatric population is alarming,” said Health Minister José Angel Portal Miranda in an op-ed published in the official government news site Cubadebate. “Extremely worrying is the daily increase in the number of infants that tested positive for COVID-19.”
No COVID-related child deaths were reported in 2020, but at least 12 children have died this year, including three 2-month-old babies.
CECMED, the country’s regulatory authority, issued an emergency authorization to start vaccinations in children 2 to 18 years old with two doses of Soberana 2 and one of Soberana Plus beginning this month. Scientists from Cuba’s Finlay Institute who developed those vaccines said the surge in cases and deaths prompted the decision.
“We have children dying, getting severe disease,” said Dr. Vicente Verez Bencomo, director of the Finlay Institute, in a video conference organized by Harvard’s David Rockefeller Center for Latin American Studies. “We are vaccinating children so we are moving closer to the point there is community immunity established.”
According to the health minister, there have been 117,500 minors diagnosed with COVID throughout the pandemic, of whom 7,660 were breastfeeding infants. The vast majority contracted the virus in the last three months after the delta variant started ravaging the island.
Those numbers, updated Sept. 6, have gotten worse: On Monday and Tuesday alone, the Ministry of Health said there were 3,727 new cases, among them 236 infants and 16 newborns.
The rise of COVID infections and deaths among children is also a concern in the U.S. and other countries. Between July 30 and Sept. 3, 17 children died in Florida. But Cuba is the only country vaccinating children that young. Bencomo said scientists and health officials felt comfortable with the decision because the Soberana vaccines “are very safe in children” since they use a traditional virus technology that is the primary platform for several vaccines already given to Cuban children.
The emergency authorization was based on data provided by the Finlay Institute of a Phase 1/2 clinical trial with 350 children between the ages of 3 and 18 that started in June in Havana.
Phase 1 clinical trials start with a small group of people that is later expanded in Phase 2 to a group that is similar to the intended population that will receive the vaccine. Phase 2 trials help determine any adverse effects and the immune response, but efficacy and safety are tested in Phase 3 trials involving thousands of people. During the COVID pandemic, some vaccine makers have shortened the time for these trials, sometimes combining different phases.
Bencomo said that “given the proven safety of this platform and ethical issues, we didn’t consider a placebo trial in children.” Instead, Cuban scientists correlated the immune response in children with that of adults given the Soberana shots and children who already got COVID.
According to a summary of the trial results published by the Finlay Institute, “after two doses of SOBERANA 02, 99.3% of the 3-to-11 year-old children and 92.9% of the 12-to-18 year-old children had an antibody response 4 times higher than the pre-vaccination level.”
The summary does not say how effective the vaccine is against infections, hospitalizations and deaths in children, data that is usually collected in Phase 3 trials.
Finlay scientists said they relied on the efficacy data of a larger clinical trial with 44,000 adults receiving two doses of Soberana 2 and one of Soberana Plus, which they claim showed they were 91.2 percent protective against symptomatic disease.
The Finlay Institute has yet to publish these results in peer-reviewed journals. Health officials said they are in talks with the World Health Organization to share the data and seek a pre-authorization for their vaccines from the international agency. Cuba is the only Latin American country that decided to develop its own vaccines and declined to participate in the COVAX initiative, a WHO program to provide cheaper or donated vaccines to low and mid-income countries.
Dr. Jarbas Barbosa, assistant director of the Pan American Health Organization, said Wednesday the organization could not comment on the use of vaccines on small children in Cuba because no vaccine has received authorization yet from the international organization to use on those age groups.
“We can’t comment because we have not seen the data presented” to Cuba’s regulator, he said. “It is a decision of each country.”
Barbosa said WHO experts were reviewing data from several vaccine makers, including Pfizer and Moderna, but it was a very “thorough process because they need to go through all the data of clinical trials with children and adolescents.”
In the U.S., the Food and Drug Administration said the most direct approach to demonstrate effectiveness for a COVID-19 vaccine candidate is based “on clinical endpoint efficacy trials showing protection against disease.” But the agency said it was open to considering other vaccines that could prove effects on other “surrogate endpoints,” like immune response based on adequate data from clinical trials and depending on the structure and characteristics of the vaccine.
Pfizer, the only company that has received FDA authorization to provide its COVID vaccine to children 12 and older, also compared immune responses between children and adults, but it conducted a Phase 2/3 “randomized, double-blinded and placebo-controlled trial” with 2,260 participants 12-15 years of age, according to the FDA’s authorization memo.
In a two-paragraph statement about the emergency authorization, CECMED said the decision was based on the results of the clinical trials with children and its comparison with results of a similar trial with adults between 19 and 80 years old.
“The results obtained in the study in the pediatric population were superior in all immunological variables with respect to the adult population aged 19 to 80,” the agency said. “The safety profile evidenced was similar between the groups compared. Children from 2 years of age are included in this approval, considering information provided by the manufacturer that justified this inclusion.”
The institution did not provide further details.
Authorities said the vaccination of 90 percent of the population, including children, will be completed by mid-November, when the country is expected to open its borders and resume in-person school classes.