Up to 95% of serious adverse drug events go unreported

This is concerning given that prescription drugs are the third leading cause of death in the U.S. and Europe, after heart disease and cancer.

adverse drug, Up to 95% of serious adverse drug events go unreported

RIO DE JANEIRO, BRAZIL – Drug reporting systems designed to capture adverse events in the population are notoriously unreliable. With the introduction of Covid vaccines, adverse effects have also become a hot topic, mainly because vaccine injury reporting systems are unreliable.

How common is it for mild, severe, or life-threatening adverse reactions to drugs or vaccines to go unreported? This is an important question because, without reporting, researchers cannot disseminate critical cost-benefit analyses of drugs to the general population.

A 2006 study published in the journal Drug Safety included more than 37 studies from 12 different countries that used various surveillance methods.

Up to 95% of serious adverse drug events go unreported
Up to 95% of serious adverse drug events go unreported. (Photo internet reproduction)

They found evidence of widespread and substantial underreporting of adverse drug reactions (ADRs). These included severe ADRs.

The median underreporting rate in the 37 studies was 94% (82-98%). There was no significant difference between the median underreporting rates calculated for general practice and hospital studies.

Five of the ten general practice studies provided evidence of a higher mean underreporting rate for all ADRs compared with the most severe or severe ADRs (95% and 80%, respectively). In comparison, in five of the eight hospital-based studies, the mean underreporting rate for more severe or severe AMRs remained high (95%).

In 19 studies examining specific drug combinations with severe/serious adverse events, the median under-reporting rate was lower but still high (85%).

This is concerning given that prescription drugs are the third leading cause of death in the U.S. and Europe, after heart disease and cancer.

A 2018 study published in the International Journal of Medical Science Research attempts to answer why this is happening. Again, this is a well-known problem among those who study it, and the data are pretty similar across publications.

The 2018 study found that physicians “know very little about AMR reporting.” They found that 32.8 percent of respondents did not know if the reaction was caused by the drug or that 46.3 percent felt it was unnecessary to report recognized reactions.

Overall, “deficient physician awareness of pharmacovigilance was found,” The researchers emphasized the need to improve physician awareness. Adequate and accessible reporting systems need to be in place to enhance reporting.


The Vaccine Adverse Event Reporting System (VAERS) of the CDC and FDA is the nationwide early warning system that monitors the safety of vaccines once they are licensed or cleared for use by the FDA.

It is a self-reporting system that does not prove causality but is designed to detect signs of adverse events (e.g., thrombotic events in the COVID-19 vaccine and myocarditis). “VAERS scientists are looking for an unusually high number of adverse event reports following a particular vaccine or a new pattern of adverse events.”

Physicians must report adverse reactions to vaccines to VAERS, but because it is a self-reporting system, it has been criticized because anyone can report a vaccine reaction. The CDC has clarified that a reported event related to vaccine administration does not mean that the vaccine caused the adverse reaction.

Still, it is concerning that VAERS received 2,149 reports of deaths between 1997 and 2013, and no “pattern of concern” was found. But as Senator Ron Johnson wrote on August 22, 2021, there were: “12,791 Covid-19 vaccine-related deaths reported in VAERS over eight months, 16,044 permanent disabilities, 51,242 hospitalizations, and a total of 571,831 adverse events related to Covid-19 vaccines.”

Approximately 17,000 deaths, 25,000 permanent disabilities, and 80,000 hospitalizations related to Covid vaccines have been reported to VAERS in the United States alone.

In a 2011 report titled “Electronic Public Health Support – Vaccine Adverse Event Reporting System (ESP: VAERS),” Harvard medical professors Ross Lazarus, Michael Klompas, and Steve Bernstein report that vaccines are underreported:

Consider that on July 16, 1999, the CDC recommended that health care providers discontinue the use of the approved RotaShield vaccine, a rotavirus vaccine, after only 15 cases of intestinal obstruction were reported to VAERS.

Of course, there is a way for researchers to use VAERS properly. Still, however you look at it, the numbers in VAERS on COVID vaccines are pretty disturbing and staggering. Even though the number of adverse events with vaccines may be minimal, one must consider the number of reports that are probably not related to the vaccine.

The question is how likely it is that a physician will report a suspected adverse effect from the vaccine. If a patient comes in three days after vaccination with some complaint, will most physicians even entertain the idea that the event might be vaccine-related?

Physicians may be biased to believe that severe vaccine injury is infrequent. The CDC claims it is 1 in a million, but how can they claim such a number when there are no proper adverse event reporting systems? Why do they not provide sources or data to support their claim?

It is also important to point out that proper reporting systems are not something that pharmaceutical companies would openly advocate. They have multiple criminal convictions and have falsified information about their drugs, including efficacy. That would be bad for business, and as far as business is concerned, Pfizer has paid one of the highest criminal fines in history.