January 11, 2021
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Questions and answers related to vaccines against Covid-19.
1.- What are vaccines against SARS-CoV-2?
There are many candidate COVID-19 vaccine products under investigation, but two of them stand out for the progress made. These are the Pfizer BioNTech vaccine and the Moderna vaccine. These vaccines have been approved by the FDA in the USA and the Pfizer-BioNTech vaccine has recently obtained approval from the European Medicines Agency (EMA).
In both cases, it has been developed with messenger RNA technology (mRNA, or mRNA in English), which has not previously been used in humans. Messenger RNA is a Natural molecule produced by our own human cells and contains the information necessary for the production of the proteins that make up each cell. This messenger RNA is carried by lipid vesicles, which allow the RNA to reach the interior of human cells, where the S protein will be produced, without the risk that it can be integrated into their DNA.
In both cases, our immune system would recognize protein S as something foreign and generate antibodies and cellular immunity against it. It is an immunization mechanism similar to that achieved with the DTP vaccine against diphtheria, tetanus and whooping cough.
2.- Are vaccines against SARS-CoV-2 safe?
The safety of a vaccine is the first thing that is checked when it reaches the research phase with humans. Vaccines are drugs that are generally administered to healthy people and for this reason the highest level of safety is required. Yes a vaccine causes serious adverse effects and is considered to be unsafe and the investigation is stopped immediately. The safety of vaccines is traditionally tested on laboratory animals and then with a small number of volunteers, but in the case of COVID-19 vaccines, thousands of people have been vaccinated prior to approval.
In the case of Moderna and Pfizer- BioNTech’s COVID-19 vaccines, they have been tested in hundreds of people during clinical phases I and II. The first vaccinations to assess safety began in March and May for vaccines from Moderna and Pfizer-BioNTech respectively, which means that the safety of the vaccines has been evaluated for at least a period ranging from 7 to 9 months.
Only mild or moderate effects (fever, local inflammation, headache, malaise, fatigue, etc.) have been observed, which are common to other vaccinations. In no case serious effects have been detected. Testing these vaccines in tens or hundreds of thousands of people, as has occurred during phase III, will allow the monitoring of rare adverse effects that may occur in less than 1 in 10,000 people, and that are also given in other vaccines. On the other hand, the follow-up of the volunteers initially vaccinated in phases I, II and III will make it possible to detect whether there are long-term adverse effects.
These infrequent and / or long-term effects have to do with the own biological variability of each person. In the same way that there are people with allergies to certain medicines, foods, etc., adverse effects can also develop to some of the components of the vaccines. The vast majority of vaccines marketed so far have shown very high safety both in the medium and long term, which is what can also be expected with these new vaccines.
3 – Can the virus become “resistant” to vaccines?
The two vaccines approved by the FDA and / or the EMA are based on immunization against the S protein of the virus, although it also contains other structural proteins. Keep in mind that viruses mutate, since it is their natural mechanism to evolve. To date, multiple mutations have been documented in the SARS-CoV-2 genome, and some of them could cause changes in the proteins of its structure.
Although protein S does not appear to have a higher mutation rate than the rest of the genome, it is not possible to predict how the virus will evolve once mass vaccination has started. In the event of accumulating several mutations in protein S, vaccines their effectiveness could be reduced. If this were the case, there is the possibility of reformulating the vaccine preparations with the information corresponding to the new virus, in the same way as is done for the seasonal influenza vaccine.
Dr. Paúl Wilches C.
Allergy Specialist
Consultorios Monte Sinai Tower 2 third floor office 304
Phone: 099 925 6953
pwilches2@gmail.com
PS: We will continue to explain topics related to COVID 19 and especially vaccines and any disease of interest related to Allergy.
Paul: pwilches2@gmail.com .
City: Cuenca
