Five Key Points About COVID Vaccines

The arrival of COVID-19 vaccines has brought sighs of relief to the EMS community. Unfortunately we still have providers who are still succumbing to this disease. There is a light at the end of the tunnel, but it’s still hard to judge how long that tunnel is.

The basis of infectious-disease transmission is the chain of infection. In this chain we see an infectious agent (the spiked COVID-19 virus), a reservoir (an infected person), a means of exit (the respiratory tract), a mode of transmission (aerosol/droplets from sneezes, coughing, speaking, breathing), a means of entry (the respiratory tract—nose and mouth—of the host), and a susceptible host (you and me).

The other key concepts are viral load, or the amount of virus in an infected person’s blood, and viral dose, the amount of virus to which a person must be exposed to become infected. We are exposed to viral dose from coughing, sneezing, breathing, and speaking. When examined within the context of viral load/dose, time, distance, and protection, it puts everything we understand about infectious disease into perspective.

You may be exposed to someone who is shedding a very low viral load. If you are both wearing masks, six feet apart, and spend only seconds in each others’ company, your chances of being infected are almost zero. If you have someone with a low viral load but one or both of you is not wearing masks, you spend prolonged time together, and you’re in an enclosed space or within six feet of each other, you have a very good chance of contracting COVID-19.

The viral dose you acquire will dictate how sick you become. If you’re both wearing masks, you reduce the dose. You may contract COVID-19, but with a very low dose, you stand a better chance than being exposed to high viral loads/doses. The problem is we don’t know how much of a viral load an asymptomatic person is shedding.

Vaccinations as part of a comprehensive system of attacking a pandemic work in conjunction with masks and social distancing by breaking the cycle of virus reproduction and transmission. If there are fewer hosts for a virus to replicate in, and if we reduce the quantity of droplets/aerosols (viral dose) you’re exposed to or expose others to by wearing a mask, thus reducing access to a mode of entry, then we stand a stronger chance of limiting the probabilities of transmission. Coupled with a vaccine that’s successful in mounting an effective immune response, we can break the chain.

Here are five key points to consider during this vaccination period.

Point #1: Vaccine Differences and How They Work

Traditional vaccine development focused on using either a dead virus (inactivated vaccines) or a weakened form of the virus (attenuated vaccines). The drawback to both is that they need to be grown in a medium, typically eggs. They take many months, in some cases up to a year, to be ready for trials. The new methods used to make the new vaccines take a much shorter time.

The first vaccines from Moderna, Pfizer, and Jansen/Johnson & Johnson used different techniques. Two focused on messenger RNA (mRNA), and the other looked at an adenovector. Neither of these techniques will change your DNA, nor do they inject the actual COVID-19 virus into your body.

The Pfizer and Moderna vaccines utilized a new technique using mRNA. This method was attempted for SARS, but SARS was brought under control so fast a vaccine never made it to the stage of clinical trials.

The COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece of what is called the spike protein. This is the spiked protein we’ve seen on the surface of the COVID-19 virus. Once the instructions (mRNA) are inside the immune cells, the cells use them to make the protein piece. The cell discards the instructions once the piece is made and then displays the protein piece on its surface.

Our immune systems recognize that the protein doesn’t belong there and rally a response that generates antibodies, exactly like what happens in natural infection. At the end of the process, our bodies have learned how to protect themselves against future infection. The benefit of mRNA vaccines, like all vaccines, is that those vaccinated gain this protection without having to risk the serious consequences of getting sick with COVID-19. The two current vaccines require two shots spaced roughly one month apart; the first is meant to boost the immune response, spurring the production of antibodies, while the second helps create even more antibodies, strengthening the immune response.

The challenge of these vaccines is that they must be stored at subzero temperatures because they are unstable. The Pfizer vaccine must be stored at minus-70ºC. Once the Pfizer vaccine is thawed, it must be reconstituted with saline. It can then be stored in a traditional vaccine refrigerator for up to five days.

The Moderna vaccine must be kept at minus-5ºC, but once it’s thawed it can stay in a vaccine refrigerator for up to 30 days, making it more stable than the Pfizer vaccine.

The Jansen/Johnson & Johnson vaccine uses a slightly different technique based on an adenovector. Using a double-stranded DNA, a small amount of genetic material that codes for a specific piece of the novel coronavirus, they leveraged a modified version using a common cold virus (adenovirus) that can enter into cells but can’t replicate inside them or cause illness. Once inside the cell the adenovirus provokes the immune system by switching on the host cell’s immune system. It does this by sending out warning signals to activate immune cells nearby. This causes the immune system to react more strongly to the spike proteins.

One of the advantages of the Jansen/Johnson & Johnson vaccine is that it is very stable. It does not need to be stored at subzero temperatures; it can be stored in a regular vaccine refrigerator for up three months. It only requires one shot.

Point #2: Effectiveness

But the Moderna and Pfizer vaccines are 95% effective, and the Jansen/Johnson & Johnson vaccine is only 66%–70% effective. Logically some of us will say that the Moderna and Pfizer vaccines must be better.

Not really. While the Jansen/Johnson & Johnson vaccine was effective 66%–70% of the time, even those for whom it did not prevent COVID-19 infection never had anything more serious than cold symptoms. No one was hospitalized, and no one died from COVID-19.

The same is true with the Moderna and Pfizer vaccines. The analysis of their COVID-19 vaccines was that they were robustly effective in preventing COVID-19, and in those who did develop it (roughly 5% for both drugs), no one developed severe disease that required hospitalization, and no one died.

Point #3: Mutations and Variants

I have heard some people say the COVID-19 virus is mutating and they may as well wait to get the “final” vaccine that will take care of all of the variants.

It is true the virus is always mutating. Look at H1N1—it’s the Spanish flu vrus from 1918 that has mutated over time. It will never go away, but we have vaccines to prevent it.

We lost the opportunity to slow the COVID-19 virus early, reducing the chance for genetic mutations and variants to develop. It appears the current set of vaccines will work on most variants. Getting vaccinated immediately will decrease the numbers of circulating virus in the community, thus reducing the opportunity for mutations to develop. If future variants become vaccine-resistant, boosters may be needed to combat them, but based on our experience it will be easier to get them out to the public.

Point #4: “I don’t need to wear a mask anymore because I’ve been vaccinated.”

You can still develop COVID after being vaccinated, and while you may not get sick enough to be hospitalized from the virus, you can still spread it to patients, family members, and coworkers. We will still need to wear masks to break the chain of infection. The sooner we get everyone vaccinated and wearing masks, the sooner we can drive this virus from our communities.

Point #5: “I don’t think I’m going to get vaccinated.”

“Is the vaccine safe?” is a fair question to ask. The most serious reactions we have seen have been in people who had allergies to flu vaccine or the components of the vaccine before. The CDC’s Advisory Committee on Immunization Practices (ACIP) says the number of anaphylaxis cases since the vaccine rollout has dropped or remained stable and appears to be much lower than background rates.

Other reactions anecdotally reported in the media—Bell’s palsy, for one—occur in the same ratio in the regular population, and there does not appear to be a causal relationship between the vaccine and other reactions. In reality this is the first vaccine we have monitored and studied to this degree in the history of medicine.

Think about it like this: During the phase I, II, and III clinical trials, the vaccines were proven safe to administer to the general populace. To date, with the Moderna and Pfizer vaccines, another 26 million people have been vaccinated since the clinical trials without issue. Nothing indicates the vaccine is unsafe or we need to halt administration. Twenty-six million doses administered is reassuring in regards to safety.

The other thing to consider is that the outcome from developing COVID-19 could be much worse. The chance to develop ground-glass opacities in the lungs; cardiomyopathies; end-organ failure due to coagulopathies; or lung fibrosis after recovering from even mild cases of COVID should give anyone pause. Our youngest and healthiest have died from COVID. In light of that the vaccine is the better choice.

Resources

CDC COVID-19 Response Team, Food and Drug Administration. Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech COVID-19 Vaccine—United States, December 14–23, 2020. MMWR, 2021 Jan 15; 70(2):46–51.

Centers for Disease Control and Prevention. Local Reactions, Systemic Reactions, Adverse Events, and Serious Adverse Events: Pfizer-BioNTech COVID-19 Vaccine, www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/reactogenicity.html.

Centers for Disease Control and Prevention. Understanding mRNA COVID-19 Vaccines, www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html.

Johnson & Johnson. Simplifying the Science of COVID-19: How Adenovector Vaccines Work, www.jnj.com/our-company/simplifying-the-science-of-covid-19-how-adenovector-vaccines-work.

Daniel R. Gerard, MS, RN, is EMS coordinator for Alameda, Calif. He is a recognized expert in EMS system delivery and design, EMS/health-service integration, and service delivery models for out-of-hospital care.