Yesterday the Google news feed on my phone listed a story by the Jerusalem Post, which I found quite interesting. It suggested that despite positive preliminary reports on their effectiveness, no one really knows what are the long-term health benefits or negative side-effects of either the Pfizer or the Moderna COVID-19 vaccines. These two vaccines are based on an entirely new product--the “messenger" RNA vaccine. While the FDA will likely approve them so long as there are no “immediate or short-term negative health effects,” the story notes that in the “race to get the public vaccinated, we are willing to take more risks,” or so says one infectious disease expert in Israel, Tal Brosh.
As described by the UK’s The Independent, the new vaccine “uses a sequence of genetic RNA material produced in a lab that, when injected into your body, must invade your cells and hijack your cells’ protein-making machinery called ribosomes to produce the viral components that subsequently train your immune system to fight the virus.” The Moderna vaccine “is programmed to make your cells produce the infamous coronavirus spike protein that gives the virus its crown-like appearance (corona is crown in Latin) for which it is named.” In other words, unlike “traditional” vaccines which employ the actual or similar virus material to induce a response, the mRNA vaccine causes healthy cells to “create” what appears to be virus, albeit a “safe” one.
Brosh stated that the mRNA vaccine acts like a USB device inserted into a computer, which runs the “program” off the device rather than “corrupting” the genetic code of the invaded cell. But the RNA material is also very “fragile,” meaning it dies quickly; it must “invade” and produce a response from a cell before it dies. This fragility is a question mark as to just how effective this type of vaccine will be not just in the long-term in inducing immune responses, but the short-term as well.
Other issues with RNA-based vaccines, as Brosh noted, is that “there are unique and unknown risks to messenger RNA vaccines, including local and systemic inflammatory responses that could lead to autoimmune conditions”--meaning that the immune system could suddenly start attacking healthy cells with the slightest “provocation.” Other issues, according to the U.S. National Institutes of Health, “include the bio-distribution and persistence of the induced immunogen expression; possible development of auto-reactive antibodies; and toxic effects of any non-native nucleotides and delivery system components.” In layman’s terms, all this basically means that RNA-based vaccines are still not sufficiently “understood” to know exactly what they will do under less than “optimal” conditions.
Most vaccines since the time of Edward Jenner use inactivated or weakened forms of the targeted virus, or a similar virus that is not dangerous to humans, that “trains” the immune system to respond to the viruses that are dangerous. These vaccines tend not to offer life-long immunity in many cases, which is why people are told to get flu shots every year; however, for certain vaccines, such as for polio, measles and mumps, when administered to children tend to have life-long benefits. There is also the DNA-based vaccines, which are genetically engineered cells that contain the DNA encoding of an “antigen”--a “foreign” entity that threatens the body--to induce and immune response. DNA-based vaccines can be manipulated to induce different responses than “traditional” vaccines; however, these vaccines also tend to have lower immunogenicity rates, meaning they don’t always induce an immune response as expected--which is why no DNA-based vaccine has been approved for use in this country.
But since the mRNA vaccines are new, and there has been such a rush to find a COVID-19 vaccine, both Pfizer and Moderna have been careful about matters of storage to prevent destruction of their more fragile product. It is being called a “logistical nightmare” to find enough adequate storage for Pfizer’s vaccine, which requires storage at minus nearly 100 degrees Fahrenheit. Moderna, which has had more experience with experimenting with mRNA vaccines, claims that its vaccine can be stored at closer to the temperatures of a typical household freezer. This all suggests that while Pfizer and Moderna have been the “hare” in the race, the turtles that have been following behind with more “traditional” vaccines may in the end win the race.
Vaccines based on the DNA and mRNA models are said to be cheaper and quicker to develop, but we have yet to see them actually work as planned in real life; we've only seen testing in optimal conditions with a delicate product that had been safely stored for best use. That may change if the Pfizer and Moderna vaccines actually prove to be both effective and safe in the long-term, but for now it is mostly just a hope and prayer that do actually work.
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