Cuba develops the world’s first conjugate vaccine for COVID-19

Subject : Science & tech

Context : Cuba’s indigenously produced vaccines- Soberana 2 and Abdala have registered strong efficacy against the SARS-CoV-2.

Concept :

Both Soberana 2 and Abdala are subunit vaccines.
In Abdala the spike protein of the coronavirus is combined with a chemically manufactured adjuvant, whereas in Soberana 2, the spike protein is chemically linked to the tetanus toxoid, making it a conjugate vaccine.

Subunit vaccines:

Rather than injecting a whole pathogen to trigger an immune response, subunit vaccines (sometimes called acellular vaccines) contain purified pieces of it, which have been specially selected for their ability to stimulate immune cells.
In the case of these subunit vaccines, a part of the virus forms the antigen and is hitched on to another construct.

Conjugate vaccines:

A conjugate vaccine is a type of vaccine which combines a weak antigen with a strong antigen as a carrier so that the immune system has a stronger immunological response to the weak antigen.
The most common conjugate vaccines are those used for Haemophilus influenza type b and the pneumococcal bacteria.

Advantages:

Major advantages of the conjugate vaccines are their ability to elicit immunological memory and to reduce asymptomatic carriage of the bacteria, resulting in marked herd immunity.
Also conjugate vaccines have a very good safety record and have been associated with very few, serious adverse events following immunization (AEFIs) after more than 20 years of use.
They give rise to improved immune memory and thus offer longer lasting protection.
They help offer protection to infants and toddlers,

Significance of the Cuban vaccines:

The design and manufacturing of the conjugate vaccines allows them to be stored in regular refrigeration settings of 2–8 degree Celsius
The methodology involved is also one of the most economical approaches to vaccine production.