Let's Talk About mRNA Vaccines: Part 2
The second part of a two-part discussion about Pfizer's Covid-19 mRNA vaccine.
On December 11, 2020, the FDA (Food and Drug Administration) approved Pfizer’s mRNA vaccine for Covid-19 emergency use. This authorization moves us one step closer to possibly containing this virus by immunization through vaccination.
This article discusses (what I consider) the top facts that you should be aware of about this new type of vaccine. This is the second part of a two-part article. The first part was released on 12/6.
Part 1 Recap:
Last week, we discussed how Pfizer’s mRNA vaccine works on the cellular level. We also debunked some common misconceptions; the vaccine mRNA does not come into contact with your DNA and the mRNA is not retained in your body. We also analyzed the possible side effects you might experience when you are vaccinated with Pfizer’s Covid-19 vaccine.
The vaccine does not contain the live or attenuated (weakened) SARS-CoV-2 virus.
The spike mRNA does not come into contact with your DNA.
What are the expected side effects of Pfizer’s vaccine?
This week’s article will continue on with a discussion of long-term immunity, if a vaccinated person remains infectious, and the problems with distributing this type of vaccine*.
*NOTE: Last week, I mentioned discussing herd immunity. However, this topic really needs a more in-depth discussion than what I can allow for this article. I apologize for this change.
4. We still don’t know how long a vaccinated person will be “immune” to Covid-19.
In order to measure how long a vaccinated person retains immunological memory for SARS-CoV-2, Pfizer would need to measure antibody efficacy ~150+ days after the second vaccine dose. Pfizer’s 95% efficacy claim was measured 7 days after the second vaccine dose in the Phase 3 trials. Efficacy measures how well the antibody response is at recognizing the virus and neutralizing it. Pfizer’s claim that their vaccine is 95% effective is only saying that there was an increase in the antibody response after the booster; it is not indicating anything about whether this response is long-term or not.
A study in September 2020 suggests that the antibodies of unvaccinated people with mild cases of Covid-19 severely decline in effectivity over time, especially in older (60+ years old) individuals. This means that people with mild infections of Covid-19 will lose protection against the virus after ~3 months (roughly 90 days).
The biotech company, Moderna, reported on December 3rd that their mRNA vaccine trial participants showed slight decline in antibody response against SARS-CoV-2 over the course of 90 days after the booster. However, “neutralizing” antibodies were still present in the participants’ serum (protein-rich component of blood). These results suggest that over time, antibody effectivity may decline, but at a slower rate in vaccinated individuals. If this is the case, a yearly vaccine may be needed to strengthen protection against the SARS-CoV-2 virus and prevent the Covid-19 disease.
5. A vaccinated person may still be able to infect other people.
This also goes for people who have recovered from Covid-19 as well. “Immunity” doesn’t mean that the virus will bounce off of you if you come into contact with it again. It only means that when you are reinfected, your body is able to recognize and neutralize the virus at a faster rate. Therefore, you may not display as severe symptoms as you did when infected for the first time. You definitely CAN carry the virus and infect the people around you.
In regards to whether a vaccinated person for Covid-19 can infect other people, if you are infected with SARS-CoV-2 right before or right after being vaccinated, you will be infectious. Upon vaccination (or even without vaccination), it takes two weeks or so for your body to build immunity against a pathogen, so if you are infected during these times, the body has not had enough time to induce a protective immune response. Considering that there has never been a 100% effective vaccine, it is safe to assume that a Covid-19 vaccinated person still has the potential to infect other people, especially unvaccinated individuals.
6. Distribution of Pfizer’s mRNA vaccine will be extremely difficult.
It will be extremely difficult to distribute the vaccine, especially to low-income populations and developing countries. Pfizer’s mRNA vaccine requires a storage temperature of roughly -70°C, +/- 10°C. At this temperature, the vaccine is viable for 30 days; this requires specialized freezers and shipping containers. Local hospitals’ freezers usually have a temperature range of -2 to -8°C and the vaccine will only be usable for 5 days at this range. Pfizer has manufactured specialized storage containers that can properly store the vaccine at the desired temperature, however, developing countries may not have the resources to properly store and distribute the vaccine. In order to ensure that the vaccines remain in the required temperature range during transfer, Pfizer utilizes GPS-enabled thermal sensors that track the location and the temperature fluctuations of the storage containers.
Ultra-low temperature freezers are necessary for long-term storage and the price of these specialized freezers are ~$25,000. This investment is difficult for struggling, rural hospital systems with low funding.
Because of these extreme temperature requirements, Pfizer’s mRNA vaccine will be extremely difficult to distribute world-wide.
As we prepare for a Covid-19 vaccine, please take this information into account when deciding on whether to be vaccinated or not. As a scientist, I strongly recommend being vaccinated. (1) You are protecting yourself, and (2) You are protecting those around you (infants, pregnant individuals, allergic reaction-prone people, etc).
Keywords:
Immunization: The process of developing immunity to a pathogen, either through natural exposure or vaccination.
Additional Readings:
Pfizer Vaccine Distribution Fact Sheet