Safety of the new vaccines is an urgent topic, and there’s conflicting information. Some is evidence-based, and some is speculative or based on incomplete information. The key concern is how quickly the vaccines were developed. Vaccines usually take a decade from idea to approval. COVID-19 vaccines were available within a year. How? Could they be safe?
Sure, mRNA technology made manufacturing the first vaccines easier and faster. Still, a typical scenario has a company researching for years before human testing with a tiny sample in case of a bad reaction. Then a second round of trials with a larger population. Finally, trials with several thousands. If the vaccine still works well and isn’t causing many adverse reactions, it applies for Emergency Use Authorization (EUA) or full FDA approval. But because of the worldwide health and economic emergency, time was compressed. Again, how?
Researching and testing vaccines takes scads of money, and funding for each step usually depends on success in the preceding trial. That’s what takes so long.
For COVID-19, funding was no obstacle. Governments were willing to fund all steps, so trials were conducted almost simultaneously. Also, genetic information about the virus was available very early on because China shared it.
The mRNA technology could therefore immediately design instructions for the vaccine. Non-mRNA vaccines used the same virus structure map and funding to make more traditional vaccines in record time. A decade, compressed into a year. No steps were “skipped” in the process.
Each vaccine applied for and received an EUA, and Pfizer recently applied for full approval. An EUA is used by the FDA to expedite a treatment or vaccine in an emergency, based on the best available evidence, usually because no alternatives exist. EUAs can be revised or revoked at any time. FDA approval is based on the same data, just more of it. It’s expected that by Fall 2021, both mRNA vaccines (Pfizer and Moderna) will be approved, with J&J following shortly.
All vaccines carry some risk of adverse reaction. Usually these are mild. Early childhood vaccines rarely have serious side effects. Low-grade fever and fussiness are most common although rarely there are severe allergic reactions or seizures. Reactions to the flu shot are similar. Overall, your chance of severe allergic reaction to a vaccine is about 1.3 in a million.
As of March 2021, the incidence of severe allergic reaction to the two mRNA COVID-19 vaccines (Moderna and Pfizer) is between 2.5 to 11.1 cases per million, usually in people with previous severe vaccine allergies. There are fewer severe allergic responses to the J&J vaccine.
The CDC recommends individuals who have a severe reaction to the first dose of the Moderna or Pfizer vaccine should consider the J&J vaccine, 28 days later, as an alternative. Allergic reactions are usually evident and treated immediately in the clinic although a few have required hospital treatment.
There was a pause in the EUA of the J&J vaccine because of a rare side-effect. The Vaccine Adverse Event Reporting System is used by the CDC and FDA to track and monitor serious reactions to vaccines given in the United States. That system identified 28 people who developed thrombosis with thrombocytopenia syndrome (TTS) following the Pfizer shot. The CDC reported that six of the 28 were males, 18 to 59.
The CDC then resumed authorization of the J&J vaccine, with a cautionary statement that individuals should be aware of this rare possible reaction. No further cases of TTS have been reported since the 10-day hiatus.
This issue with the J&J vaccine raised questions. Evidence suggests a causal relationship between the J&J vaccine and this rare but often fatal syndrome in which a blood clot forms in the brain or abdomen, along with low platelet count.
Platelets are blood cells that help stop bleeding. Ordinarily blood clots are treated with heparin, a blood thinner, to dissolve clots. But in the case of TTS, the use of heparin is potentially deadly because of the clotting problem associated with the low platelet count. Using heparin could lead to a massive hemorrhage and death. This side effect was also noted with the Astra Zeneca vaccine (which is not authorized for use in the United States.)
Arguments for continued use of the J&J vaccine are that TTS occurred in only 28 of approximately 1 million people vaccinated, and that its potential harmful effects are outweighed by its benefits. A report by the University of California at San Diego Medical Center noted that 20 percent of hospitalized COVID-19 patients developed blood clots in their veins.
That metric rose to 31percent of those in intensive care. Blood clots among the COVID-19 patients led to higher death rates and amputations. The risk of blood clots is therefore higher among patients with COVID-19 requiring hospitalization than from the J&J vaccine.
Arguments against the re-authorization of the Pfizer vaccine are that there are other vaccines not associated with TTS, and while there haven’t been any new reports since the J&J vaccine was re-authorized, it was only re-authorized on April 23, just three weeks ago. It remains to be seen whether there will be other cases of TTS and whether the frequency of such cases warrant further consideration of the J&J vaccine’s safety.
Possible unknown future side effects are another subject of anxiety. Realistically, if side effects are going to happen, they generally happen within six weeks of receiving a vaccine. Accordingly, the FDA required each of the authorized COVID-19 vaccines to be studied for at least eight weeks after the final dose. So far there are no indications of other adverse effects. Since the vaccines are not able to alter a patient’s DNA, speculation about future human mutations is unfounded.
There are side effects from the COVID-19 vaccines, as with all vaccines. Evidence points to benefits outstripping risks, and these vaccines compare favorably to others.
For more COVID-19 vaccine information visit the cdc.gov website.