Let’s talk about Covid-19 vaccines

It was with great joy and hope that we received the news on December 24, 2020 in Costa Rica from the Health Authorities that the Covid-19 vaccination program would initiate. Without a doubt, vaccination is the most effective measure to reduce the number of cases and deaths arising from SARS Cov-2 infection.

However, to ensure the expected benefits and results, rigorous and strategic planning is required for the application of these vaccines.

How do COVID-19 vaccines work?

COVID-19 vaccines help our body develop immunity against the virus without having to contract the disease.

The available vaccines work differently to protect our bodies by stimulating the production of “memory” T cells and B lymphocytes to help us produce antibodies that help us successfully fight the virus.

After vaccination it usually takes a few weeks for the body to produce T cells and B lymphocytes. Therefore, a person may become infected with the virus that causes COVID-19 just before or after being vaccinated and get sick because the vaccine did not have enough time to generate sufficient protection.

Types of vaccines

At this time, there are three main types of COVID-19 vaccines which have already completed the research stages required to be applied to the general population.

In Costa Rica, the first vaccine to be given to approximately 1.5 million citizens is the RNA messenger (RNAm) vaccine, developed by BioNTech and produced and distributed by Pfizer.

Important information about the vaccine

• The RNAm vaccine contains proteins from the SARS CoV-2 virus. This RNAm instructs our cells to copy that part of the virus which is called S protein (spike). The process of copying that protein occurs in the cytoplasm of the human cell, in the ribosome. These proteins are the ones that stimulate the production of B and T lymphocytes that will fight against the virus when we face it in real life or when we come into contact with a person who has the virus.
• The RNAm that was injected through the vaccine disappears. By that time our cells have already copied the protein sequence, and these proteins are generated on the cell surface to stimulate more immune cells with this specific message and continue to activate our immune system to fight against the virus through of the production of antibodies, specifically T and B cells that fight and destroy the virus.
• By the end of the process, our bodies will have learned how to protect against future exposure to COV-2 SARS, and exposure will not result in severe illness or fatal disease from which some people suffer.
• This vaccine requires two intramuscular doses to achieve the protection of more than 95% effectivity, which was achieved in clinical studies. Dosages are applied within 21 days of each other.
• These vaccines are safe in the sense that it is not possible for them to produce the disease because the complete virus is not administered, only a small portion of S protein, which produces a powerful immune response, that offers significant protection. However, it can lead to a very intense reaction, known as reactogenicity, which can occur with a higher incidence in young people or in people with a history of severe allergies to certain foods, medicines, or vaccines.
• For this reason, these vaccines should be administered in centers capable of treating severe allergic reactions, replete with all the necessary medicines and equipment.
• One of the things that makes the application of this vaccine difficult is the fact that the RNAm is very labile and needs to be frozen at extremely low temperature and needs special freezers for the respective storage. Once thawed, the dose should be administered within 6 hours.
• Our country has the necessary infrastructure for this type of vaccine in the Greater Metropolitan San Jose Area (GAM), therefore, adequate planning for the application of the vaccine in rural areas is extremely important.
• The vaccine has shown the ability to protect against the virus; however, it is necessary to continue adhering to protective measures already in place for many months (use of the mask, eye protection, social distancing, and hand washing) until the vaccine has administered and generated immunity greater than 80% in the general population.
• These conditions require many months, and it will be a while before we are able to say that we have eliminated the virus so that we can resume our customary way of life before the pandemic.

RNAm vaccines are new, but not unknown.

Scientists have studied and worked on RNAm vaccines for decades. However, interest in these vaccines has increased because they can be developed in a laboratory with materials that are readily available. This means that the procedure can be standardized and expanded to make vaccine development faster than traditional vaccine production methods.

Dr. Gisela Herrera

Specialist in Internal Medicine and Infectious Disease

Hospital CIMA