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Some 200 COVID-19 vaccines are being developed worldwide, and 23 candidates have advanced to phase III clinical trials (as of 25 March 2021). Though no other Latin American country has developed a vaccine of its own, two of the 23 now in phase III trials are Cuban: Soberana 02 and Abdala. And Cuba also has three other vaccine candidates in earlier stage trials: Soberana 01, Soberana Plus, and Mambisa. So how has Cuba managed to develop five COVID-19 vaccines in such a short time?

Cuba’s biotech sector is unique. It is entirely state-owned and free of private interests, with innovation channelled to meet public health needs and no profit-seeking in the domestic market. Dozens of research and development institutions collaborate, sharing resources and knowledge instead of competing, which facilitates a fast track from research and innovation to trials and application. Cuba has the capacity to produce 60-70% of the medicines it consumes domestically, an imperative due to the US blockade and the cost of medicines in the international market. There is also continuous and comprehensive circulation of information and personnel between universities, research centres, and the public health system. These various elements have proven vital in the development of Cuba’s COVID-19 vaccines.

HOW DO CUBA’S COVID-19 VACCINE WORK?

There are five types of COVID-19 vaccines being developed globally:

• Viral vector vaccines that use an unrelated and harmless virus modified to deliver SARS-CoV-2 genetic material (as with the Oxford AstraZeneca, Gamaleya, and SputnikV vaccines)
• Genetic vaccines containing a segment of SARS-CoV-2 virus genetic material (Pfizer, Moderna)
• Inactivated vaccines containing deactivated SARS-CoV-2 virus (Sinovac/Butantan, SinoPharm, Bharat Biotec)
• Attenuated vaccines containing weakened SARS-CoV-2 virus (Codagenix)
• Protein vaccines containing COVID-derived proteins that trigger an immune response (Novavax, Sanofi/GSK)

The five Cuban vaccines undergoing clinical trials are all protein vaccines. This means that they carry a portion of the spike protein that the virus uses to bind to human cells, which in turn generates neutralising antibodies that block this binding process.

Dr Marlene Ramírez González explained to the British Medical Journal that the Cuban vaccines are subunit vaccines, “one of the most economical approaches, and the type for which Cuba has the greatest know-how and infrastructure … [They are] based only on the part [of the COVID antigen] that is involved in contact with the cell’s receptor [the receptor-binding domain], which is also the one that induces the greatest amount of neutralizing antibodies”. She added that while Cuba’s vaccines are not alone in using this strategy, Soberana 02 is unique amongst COVID vaccines for another reason: it combines the antigen’s receptor-binding domain with a deactivated form of tetanus in order to boost immune response, making it the only existing “conjugate vaccine” for COVID-19.

Over email, Idania Caballero, a pharmaceutical scientist at BioCubaFarma, pointed out that these vaccines build on decades of medical science and work on infectious diseases:

The Soberana vaccines are produced by the Finlay Institute in partnership with the Centre for Molecular Immunology and the National Biopreparations Centre. The name Soberana means “sovereign”, reflecting their economic and political importance for the island – without this domestic production, Cuba would struggle to access foreign vaccines either because of their cost in international markets or because of the longstanding US embargo. These vaccines work by inserting genetic information into superior mammalian cells. Soberana Plus is the first vaccine for convalescent COVID-19 patients to reach the clinical trial stage.

The other vaccines, Abdala and Mambisa (an intranasal, needle-free vaccine), are produced by the Centre for Genetic Engineering and Biotechnology (CIGB). Abdala is named for a poem by the national hero José Martí, and Mambisa is named for soldiers who fought against Spanish rule in the mid- to late 19th century. These vaccines insert genetic information into a less evolved, unicellular microorganism (the yeast Pichia Pastoris). They build on the long experience and impressive record of the CIGB, whose hepatitis B vaccines have been in use in Cuba for 25 years.