The director of the Area of Medicines and Health Technologies of the Colombian Ministry of Health, Leonardo Arregocés, explained that the vaccines against covid-19 from the pharmaceutical companies Pfizer, Janssen and Moderna will not be available to administer booster doses.
Also, the official assured that are advising against the use of Sinovac vaccines for the additional dose, since the inactivated virus vaccine would not serve the purpose of refreshing immunity with the same intensity as the others. According to Arregocés, “we are hardly using Sinovac, because it has a less immunogenic profile in adults”.
Pharmaceutical vaccines Janssen and AstraZeneca are viral vector. That is, they contain a modified virus capable of infect every cell in the body with a desirable gene; in this case, the one that will produce resistance against serious disease in the event that a person becomes infected spontaneously.
Vaccines with viral vector are safe and effective as booster doses. The difference between the two brands is that the AstraZeneca vaccine requires two doses to complete a basic schedule, while the Janssen only requires one.
In a country that has yet to initiate and complete vaccination schedules for 28 million people, some of whom live in areas of difficult access or conflict, it is necessary to make the best possible use of Janssen pods. Therefore, these will be separated for people who have not yet started their vaccination.
Pharmaceutical vaccines Pfizer and Moderna use messenger RNA technology. It is a molecule that, when approaching cells, creates a protein very similar to the one found on the surface of SARS-CoV-2. When the cells detect the foreign body, they seek to defend themselves against it and provoke an immunological chain reaction, which in the long term is what protects them from the virus.
Pharmaceutical companies conducted trials of their vaccines in various types of population. For example, Pfizer has successfully tested pregnant women and Moderna has tested its vaccines on young people.
As it is necessary to guarantee the vaccination of young people -who will start face-to-face- and pregnant women -at high risk of dying from covid-, messenger RNA vaccines will be reserved to complete the schedules of these two populations.
According to the official, the booster vaccine is subject to the patient’s wishes and the availability of vaccines at the vaccination post you have attended.
Worldwide the heterologous system is being recommended to choose the booster dose: if a messenger RNA vaccine (Pfizer, Moderna) was received in the initial schedule, a viral vector vaccine (Janssen, AstraZeneca) should be preferred and vice versa.
However, in Colombia there are two drawbacks to following this recommendation: there is a shortage of messenger RNA vaccines and the percentage of Colombians without vaccination is still too high. In addition, the homologous scheme (using the same type of vaccine for the booster) has also shown good results.
With all those factors in mind, the booster options are reduced to one: the AstraZeneca vaccine, which is double dose and viral vector.
In any case, the official from the Ministry of Health left open the options of using messenger RNA vaccines to reinforce protection, a decision that is left to the discretion of each vaccination point and the availability of doses that it has.
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