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How vaccine adverse effects are investigated

SÃO PAULO, SP (FOLHAPRESS) – Since the beginning of vaccination against Covid-19, doubts, questions, lies and errors have been raised about serious adverse effects. But rest assured: vaccines have been tested, are safe and efficient in preventing more serious paintings and deaths from the disease.

There are, of course, widely documented adverse events in relation to vaccines for the most diverse diseases. In the case of immunizations against Sars-CoV-2, pain at the application site, headaches, chills and even feverish sensation are common. In general, they are mild effects.

But there are also adverse events considered serious. Within this group, situations that require hospitalization for at least 24 hours or prolongation of existing hospitalization, significant dysfunction and/or persistent disability, congenital anomaly, risk of death or death itself are considered.

And, in order to become aware of any events, act and try to avoid more serious problems, there is an international manual, national documents -such as the Epidemiological Surveillance of Post-Vaccination Adverse Events Manual- and a vaccine pharmacovigilance system at national and state levels to documentation and follow-up of cases.

The first thing to consider when determining and classifying an adverse event is temporality: the time relationship between the event that occurred (a pain at the site where the injection was given, for example) and the vaccine.

And here one thing should already be highlighted. As the WHO (World Health Organization) points out, a post-vaccination adverse event has a built-in “time” issue, but not necessarily a causal relationship. That is, even though an event has occurred after vaccination, this does not mean that the vaccine caused the problem, which may originate from a fortuitous event or from previously existing diseases.

A person takes a vaccine and is then run over, exemplifies Renato Kfouri, pediatrician, infectious disease specialist and director of SBIm (Brazilian Society of Immunizations). This is an “event” occurring after vaccination, but not necessarily the vaccine is to blame.

Practically the entire population of the country is being immunized and, therefore, with a vaccination campaign of this scale, it is common for vaccination to end in the time window of other events. A stroke, a heart attack, a traffic accident, all this can happen and enter a time frame close to vaccination.

“Covid put us in a very complicated situation. We are vaccinating a lot of people at the same time. Everything that happens in people’s lives is temporally associated with vaccines”, says Eder Gatti, infectious disease specialist at the immunization division of the Center for Epidemiological Surveillance of São Paulo. Paul. “These coincidences end up becoming more frequent in mass vaccination.”

In addition, the very moment of use of new immunizers can sensitize event reporting mechanisms more, which pay more attention to any event – which translates into more adverse events reported.

A recent example that helps to visualize the situation occurred in Lençóis Paulista, in the interior of São Paulo, where a ten-year-old child had an arrhythmia. The medical problem happened about 12 hours after the application of the Pfizer immunizer.

This time difference was already a good indication that the vaccine had nothing to do with the matter, says Gatti, responsible for investigating the case.

The Lençóis case helps to exemplify the other essential point in the investigation of adverse events: causality. One of the questions asked when faced with a case of a post-vaccination adverse event is “Did the vaccine given to this individual cause the reported event?”.

From then on, one begins to look at the medical literature in relation to the vaccine, laboratory tests, biological plausibility and consideration of other factors that may explain the situation.

“Pfizer gives myocarditis in rare, rare cases,” says Gatti. In these very rare cases, an immunological reaction occurs, which leads to an inflammatory infiltration in the heart. The process, therefore, takes days to develop.

An electrocardiogram and the information that the municipality provided already pointed to evidence that there was no relationship with the vaccine. In any case, a cardiologist was consulted, and the case was presented and discussed at a meeting with municipal representatives and specialists in various areas.

The conclusion of this investigation was that there was no relationship between the Covid vaccine and the event that occurred with the child. The cause of the arrhythmia was Wolff-Parkinson-White syndrome, which until then had not been diagnosed.

The whole process, in this case, was accelerated, even by the dimension that the subject gained. Normally, under standard pharmacovigilance procedure, the case would be notified, investigated by the municipality, which would then pass the information on to the state to complete the investigation. With Covid, there is also a committee of experts that meets, in recorded meetings, to analyze more complex cases.

The speed and effectiveness of the investigation are even highlighted by the WHO, which says that failures in this process can undermine the confidence of the population and lead to “dramatic consequences for vaccine coverage and incidence of diseases”.

But adverse events do not always rely on speed, availability of information and follow-up. “Unfortunately, Brazil is not São Paulo. Sometimes, that’s not what happens. It stays there, they don’t investigate, they don’t have resources, they don’t have specialists”, says Kfouri. “It is attributed to the vaccine, with only the temporal relationship. The vaccine takes the blame, and people are afraid.”

Gatti, in the same vein, points out that, although some cases can be accelerated in the surveillance process, not all are like that. “Many times the municipalities do not manage to make the notification in time.”

Kfouri recalls that adverse events are reported in all existing drugs. “And you use it because the benefit is much greater,” he says.

Finally, the final classification of an adverse event case is not simply yes/no to a vaccine relationship. The result is within a scale.

If there is enough information to conduct the investigation, the case can be classified from A1 to A4, for events with a causal association with the immunizer. Within this group are the possibilities of an event actually caused by the product (A1); a reaction caused by a production defect in the vaccine, that is, its quality (A2); immunization errors, that is, at the time of application (A3); and a reaction to application anxiety (A4).

The second group includes events classified as indeterminate, in which there is a temporal relationship, but there is insufficient evidence to establish a causal relationship with the vaccine (B1); and conflicting investigational data regarding causality (B2).

The penultimate classification group is the one that points to an inconsistency in the causal relationship, that is, there is only a coincidence of the event with the vaccine (C).

Finally, there is a group destined for unclassifiable cases, due to lack of adequate information.

According to Gatti, it is important that the population, when faced with a more unusual event (other than simple things like redness, pain and even fever), seek the health system, which will provide assistance and initiate an investigation.

Now, the next time someone tells you about a post-vaccination adverse event, you already know that this doesn’t necessarily mean that vaccines have anything to do with it.

Posted on Tue, 25 Jan 2022 09:43:00 -0300

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