Last week Johnson & Johnson announced that they were temporarily pausing their COVID-19 vaccine clinical studies in order to review and evaluate an unexpected illness in an individual participating in their study, less than 3 weeks after their Phase 3 study had started. Another COVID-19 vaccine, developed by the University of Oxford, also had its clinical studies paused in July and September for similar reasons. Read on for my thoughts on what this may mean for potential COVID-19 vaccines and their safety.
Because of patient privacy laws, we don’t, and can’t, know much about the participant or their illness. We only have pieces of the puzzle and can only guess at what the larger picture shows. This is my best guess, by no means a definitive answer.
Both the Johnson & Johnson and AstraZeneca/University of Oxford vaccines use a weakened form of adenovirus to carry DNA for the virus that causes COVID-19 (an “adenovirus vector”). One unexpected illness could happen randomly. Two unexpected illnesses in the same study might also be a coincidence. Three unexpected illnesses in people participating in studies of two different adenovirus vector COVID-19 vaccines looks an awful lot like a pattern worth examining.
Does this mean that the adenovirus vector vaccines caused the illnesses? Not necessarily. Not everything that looks like a pattern actually is one. Sometimes things occur randomly, and sometimes they reflect some other factor. If a large number of children at a given elementary school like a certain block-themed video game, it probably means that game is popular among elementary school-aged children, not that the school caused them to play it. If two of my coworkers and I both wear purple on the same day without planning it out in advance, our shared clothing color is probably a coincidence that doesn’t mean anything at all.
Right now, we don’t know whether these illnesses are caused by the adenovirus vector COVID-19 vaccines, caused by some other unrelated factor, or entirely random and coincidental. As I mentioned in my post about the AstraZeneca/University of Oxford clinical study’s pause, the fact that the researchers have paused the study means that they are taking the participant’s illness seriously, following guidance and waiting for an independent group of scientists and physicians to review the illness and the study before continuing it. Considering the amount of pressure we can only assume they must be under to finish their clinical studies soon, it is both admirable and reassuring to see that they are following the recommended steps to make sure that their vaccine is safe.
If the adenovirus vector vaccines did cause the illnesses, then will that mean that they’re unsafe for use? Also not necessarily. If reviewers find that the vaccines causes these unexpected illnesses, then they will also look at how the vaccine caused them, how common and severe the reaction was, and anything that the sick people may have had in common.
It could be that they had some common risk factor. Some vaccines or medications can’t be given to some people, but are safe to use in others. For example, the measles-mumps-rubella (MMR) vaccine can’t be given to pregnant women, people with weakened immune system or certain other illnesses, but can and should be safely given to most healthy children and adults who haven’t yet received it.
If the illness was rare and/or mild, then they might find that the benefits of the vaccine outweigh the risks of a reaction to the vaccine. There are risks to everything in life – not only to vaccines and medicines, but also to “natural” treatments and to refusing treatments. When physicians and scientists decide whether a particular vaccine or medicine is safe to use, they don’t only look at whether there are risks associated with that vaccine or medicine; they look at the risk-benefit ratio. In other words, they compare the risks of that vaccine or medicine against the benefits of taking it. If there are more risks than benefits for a given patient, then it shouldn’t be used. If there are more benefits than risks, then it should. We can only wait to see the risk-benefit ratio for these vaccines.
What if the FDA doesn’t approve the adenovirus vector vaccines? Would that mean there wouldn’t be a vaccine against COVID-19? No, it does not.
As of this writing, there are 46 potential COVID-19 vaccines in human studies, and at least another 91 in the early stages of research. Additionally, two other COVID-19 vaccines in Phase 3 clinical studies – by Moderna and Pfizer – use an entirely different technology based on messenger RNA (mRNA) and there are several other vaccines in the early stages of development that use other technologies. Even if the adenovirus vector vaccines are found to cause this illness, there is no reason I can think of why an mRNA vaccine or one created using some other technology would have the same effect.
Most vaccines and medications under research and development don’t make it all the way through to approval; that’s just how the scientific process works. Hopefully researchers will find that the adenovirus vector vaccines are safe to use, but if they don’t then it would be just 2 vaccines down out of 130-odd under development. I do believe that researchers will find a safe and effective COVID-19 vaccine, likely within the next few months. Until then, keep wearing your masks, social distancing, and making responsible decisions.
Stay safe and healthy, and let me know in the comments if you have any other questions about these vaccines,
😷 Dr. B.