In recent months there has been much controversy surrounding the different vaccines available against Covid-19, and it has even been questioned whether we should be vaccinated against the disease. The fact that there were occasional side effects in some patients after receiving the vaccine caused panic and many theories began to emerge. Dr. Baca Cots, a specialist in Pediatrics and a great expert in vaccines, clarifies all the doubts in the following interview.
Dr. Baca, what are vaccines and what are they for?
Vaccines are preparations produced from bacteria, attenuated or killed viruses and obtained by genetic engineering or other complex technologies. Vaccines are administered to people with the aim of generating active immunity (defenses) and lasting over time against an infection, stimulating the production of antibodies. The end result is to protect us against infections, since our immune system will be able to recognize the infection and destroy it.
When we administer a vaccine, our immune system recognizes the antigen (a small part of the infectious agent), detects the disease and produces antibodies (defenses) against it.
Basically we trick the organism and, through the immune system, “convince” it that it is being affected by an infection and that it needs to produce “defenses” against this infection. This situation is always active, for life, watching for the appearance of new infections. We call it “permanent immunity” and it serves for our entire life.
Another even more complex “technological” leap are the combined vaccines, such as the hexavalent vaccine, which allow simultaneous immunization against several major diseases, in this case six diseases.
Is it advisable to get vaccinated? Why?
The greatest success in the history of preventive medicine, next to water purification, is vaccines, which have prevented the illness and death of millions of people. In some cases, such as smallpox or polio, the disease has even been eradicated. Currently, the safety profile of vaccines is excellent and the method that works most effectively to avoid a return to the pandemics that humanity has endured are vaccines.
Is it good to be vaccinated for pathologies such as the common flu, for example?
Influenza is a major health problem. It causes high mortality and many complications. Added to all this are the social costs and the great economic damage. Vaccination is the only real way to avoid influenza and, above all, its serious complications. In addition, we must have the “social conscience” that, by getting vaccinated, we manage to avoid the disease and prevent its transmission to other fellow citizens.
The World Health Organization (WHO) classifies vaccines as follows:
- COVID-19 mRNA vaccines: this is a pioneering approach that uses modified RNA or DNA to elicit an immune response (defenses). These are the Pfizer-BioNTech and Moderna vaccines, as well as CureVac.
- Another possibility are those Covid vaccines that use viral vectors. In these vaccines another virus is injected which is “less harmful” but which carries “parts” of the coronavirus, generating an immune defense response. This is the case of Janssen, Johnson & Johnson, and Astra Zeneca Vaxzevria. Gamaleya (SputnitV) researchers used common cold viruses, opting for two different adenovirus vectors (rAd26 and rAd5) administered separately in a first and second dose, 21 days apart.
- Another modality is to use innocuous protein fragments or protein structures that mimic the virus causing Covid-19, in order to generate an immune response. The main exponent of protein-based Covid vaccines is Novavax.
- Covid vaccines with inactivated or attenuated viruses: by injecting an inactivated virus into the body. CoronaVac serum (produced in China) and Sinovac have given the green light to inoculate three other vaccines (two from Sinopharm and one from Cansino). They use a previously inactivated or attenuated virus, so that it does not cause disease, but still generates an immune response.
- Using an antigen derived from the peak protein (S) of coronavirus, as is the case with Novavax.
Are all vaccines equally safe, and what side effects are occurring with each of them?
Side effects caused by coronavirus vaccines are more frequent among young people. The side effects of the Covid-19 vaccines are not very different from the other vaccines and are easily tolerated. For example, swelling in the arm, headache, fever or general malaise.
In these first months of vaccination, the adverse effects caused by the doses of Pfizer, Moderna and AstraZeneca have been found to coincide with those detected in clinical trials.
Pfizer. According to the technical data sheet, the most common reactions are:
- Pain in the area where the injection is given (80%).
- Tiredness (60%)
- Headache (50%)
Modern. Among the most common symptoms are, in this order:
- Pain at the injection site (92%)
- Tiredness (70%)
- Headache (64.7%)
AstraZeneca. The symptoms most commonly reported by study participants were:
- Pain at the injection site (63.7%).
- General discomfort (54.2%)
- Headache (52.6%)
Janssen. In the clinical trials, patients who had symptoms manifested them one or two days after vaccination, rarely more than seven days later. They were more common in the 18-59 age group than among those over 60 years of age and, in the majority of those affected, were mild or moderate in nature. The most common were:
- Pain at the injection site (48.6%).
- Headache (38.9%)
- Tiredness (38.2%)
These last two preparations have in common the use of an adenovirus vector in their production. Very exceptionally, cerebral sinus thrombosis has appeared, the clinical picture of which is much more frequent in women of about 30 years of age. This type of thrombosis detected after vaccination is characterized not only by clots but also by a sharp drop in platelets (thrombocytopenia). This rare type of thrombosis had already been observed in the past in some patients treated with heparin. There are at least two other vaccines that also use adenoviruses, the Russian Sputnik and the Chinese Cansino. At the moment there are no warnings that they cause thrombosis, but they are also countries without transparency about vaccination data.
What does it depend on whether these side effects occur, if the vaccines have undergone many testing processes?
To demonstrate their safety and efficacy, each new vaccine undergoes a “scientific roadmap” involving a multitude of steps. Initially, experiments are carried out in animal cell cultures, assessing the molecules to work in humans. If the results are ideal, the product is tested in humans, in three phases: starting with a limited number of volunteers in phase one and, as knowledge progresses, we evolve to tens of thousands of participants in phase three to assess dosing and administration.
Covid-19 vaccines have gone through (and continue to go through) this complex process. But to ensure the safety of the vaccines we work with protocols called “parallel observations”, taking advantage of this to do “parallel” studies, which will lead us to secondary results. The last phase is called effectiveness and is the administration to very large populations.
Are Covid-19 vaccines in children recommended?
The pharmaceutical companies BioNTech and Pfizer have applied to the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA). (FDA) to authorize its vaccine against Covid in adolescents aged 12 to 15 years after proving that it has a high efficacy and safety in this age group. Its use will ensure safer school attendance, with the presence of all students and, probably, without the need for any measures that would affect the normal conduct of classes. In addition to contributing to a safe
r school, the vaccination of children and adolescents against Covid-19 would not only protect them, but also their grandparents and other vulnerable people in their environment.
For all these reasons, trials have been initiated worldwide for use in infants over six months of age. Ultimately, all this may mean that the next school year will come with a new impetus to resume “normal” face-to-face classes and that, in the medium term, with the vaccine for all pediatric ages, the family environment will be safer and children will be more protected.