Covid-19 Vaccines

A review of the most promising Covid-19 vaccinations

The human body has an impressive immune system to help protect us against disease and infection. For the most part, it’s incredibly efficient in fighting against foreign microorganisms. The problem is, some invasive pathogens can overwhelm our immune system more than others leading us to develop severe symptoms of the illness.

Why Covid-19 Is so Threatening to Our Health

Covid-19, also known as the novel Coronavirus, is an infectious virus that has the potential of being 10 times deadlier than the seasonal flu. Although scientists don’t know for certain until more widespread testing becomes available, this sort of infection can lead to 0.1% of death in the people it infects. Covid-19 is predicted to be as contagious as the seasonal flu, showing that 1 person is likely to infect 2 to 3 people.

Another important reason it threatens our health is that no one is immune to it. As a novel virus, Covid-19 has not been introduced to humans, therefore none of us have built an immunity to fight off its infectious qualities. Spread as easily as influenza and infecting the upper respiratory system, Covid-19 presents many issues for our health if it’s not controlled.

What Can We Do About It?

To effectively fight back and overcome the virus, we need to develop herd immunity. This is a form of protection that occurs when enough people develop the antibodies that minimize the transmission in their community.

Herd immunity can develop in 1 of 2 ways:

  1. Enough people become infected with the virus/get sick
  2. Enough people get vaccinated

In both scenarios, we will build the antibodies and proteins necessary to fight Covid-19. However, in the first instance, there is widespread uncertainty about individual symptom severity. Also, it involves the added risk of spreading the virus to others. This can present even more issues if it’s spread to the more vulnerable population (elderly, immune suppressed, chronically ill, etc.)

Why Do We Vaccinate?

Getting vaccinated is not only beneficial, but it’s essential for the health of our population. They’re used as a primary form of prevention, meaning they’re effective in protecting people from getting sick. Simply put, vaccines work by ‘teaching’ our immune system how to recognize a specific pathogen to then eliminate it from our bodies. This way, when we are exposed to the Covid-19 virus, our body’s immune system is well-equipped with the tools to fight back.

Like any other vaccination, the Covid-19 vaccination is only useful if enough people receive it. When this happens society will successfully develop herd immunity.

Let’s take a look at the most promising Coronavirus vaccinations available.

1.  Pfizer-BioNTech

Pfizer-BioNTech’s vaccination is a well-known Covid-19 vaccine for being the first on the market to be approved by the FDA.

What is in this vaccine?

The Pfizer vaccination introduces an active, synthetic form of messenger RNA (mRNA) that provides essential instructions for our cells to create the viral protein. More specifically, it gives specialized immune cells information to make the virus’s spike protein to enter your cells.

Spike proteins are recognized as “foreign pathogens” by our immune system. Once exposed to these proteins, our B and T immune cells become activated and work towards destroying the virus.

This process is essential to build an immune memory. When we are exposed to the actual virus in the future, our immune system is primed to efficiently eliminate it without potential symptoms of sickness.

How effective is this vaccine?

Current data demonstrate that the Pfizer vaccine is about 95% effective towards eliminating the Covid-19 virus. This has been determined through a phase 3 clinical trial involving 42,000 participants. Half of them had received the active vaccine and the other half received an inactive placebo.

The results showed that out of 170 people who got sick with COVID-19, 162 of them were in the placebo group. The 8 participants that were in the vaccine group accounted for the 5% deemed ‘non-effective’.

What are the required doses?

The Pfizer vaccine uses two doses that are separated by 21 days. Each dose consists of 30 micrograms of vaccination. 

How long is it expected to last?

This information is difficult to address at this time since the vaccination is only recently approved. However, it is well-understood that protective immunity builds up within 4 weeks after the initial dose. Further research needs to be done following the second dose.

How is this vaccine stored?

For long term stability, the Pfizer vaccine needs to be stored in specialized cooling equipment at -70° C. Once thawed, the vaccine can be comfortably stored in a regular fridge between 2-8° C for up to 5 days.

Are there any safety concerns associated with this vaccine?

Throughout the phase 3 trial, the Pfizer vaccination didn’t cause any serious adverse events. However, the FDA has recorded 4 participants having experienced Bell’s Palsy after administration. Bell’s Palsy is a temporary facial paralysis that is reported in the general population in the same frequency as with this vaccination. There is no clear evidence to conclude a causal relationship. 

Other common side effects include fatigue, headaches, muscle pain, and some mild anaphylaxis.

2.  Moderna

Moderna is a biotech company based in Cambridge, Massachusetts that’s the second FDA-approved Covid-19 vaccine.

What is in this vaccine?

The Moderna vaccination called mRNA-1273 is another synthetic mRNA working to lay down instructions for Covid-19 protein creation. Moderna uses the same technology as Pfizer making it very similar in efficacy and safety.

How effective is this vaccine?

Moderna’s phase 3 clinical trial was the first Covid-19 trial that was funded by the U.S government. Moderna vaccine efficacy is comparable to that of Pfizer, having expressed a 94.1% success rate in preventing symptomatic Covid-19 participants. Although their data expresses slightly lower efficacy in the 65+ participants, the FDA informs the public that this is due to lower test subjects in this age group.

What are the required doses?

Much like Pfizer, the Moderna vaccine also requires two doses: an initial priming dose, followed by a booster dose. However, the difference here is the interval between the two doses is 28 days rather than 21 days.

It also requires just greater than 3x the amount of vaccine compared to Pfizer by using 100 micrograms per dose. 

How is this vaccine stored?

Unlike the Pfizer vaccine, Moderna’s vaccine does not require extreme freezing temperature storage making it more mobile and readily available. Rather, it requires storage at -20° C in a regular freezer. This makes it a more promising candidate for the rural communities around the globe.

Are there any safety concerns associated with this vaccine?

Based on the results of the clinical trial, the most common side effects seen with the Moderna vaccine include injection site pain, fatigue, headache, and muscle and joint pain. Some people reported mild to moderate fever; however many of these side effects are a sign of immune response rather than a direct result of the vaccination.

Due to the novelty of the Moderna vaccination, it’s unclear if there will be the same side effects as Pfizer when performed outside of the clinical trial environment.

3.  AstraZeneca

AstraZeneca is a UK-based company that develops its Covid-19 vaccination through Oxford University. This vaccine is on its way to becoming FDA approved in the upcoming months.

What is in this vaccine?

The ChAsOx1 nCoV-19 vaccine, known better as the ‘Oxford vaccine’, was developed by researchers at the University of Oxford and AstraZeneca.

The AstraZeneca vaccine is developed from a weakened version of a common cold virus that infects chimpanzees. This virus, known as an adenovirus, is genetically altered to code for the spike proteins presented in Covid-19. Their goal in this, like both Pfizer and Moderna, is to teach our body’s immune system to recognize these spike proteins as foreign pathogens and destroy them.

How effective is this vaccine?

The AstraZeneca vaccine has demonstrated 70% efficacy in prevention of Covid-19 in their phase 3 clinical trials while also concluding 90% efficacy when given at the right dose. The results are still to be determined as the trial has not been completed.

This vaccine is proving to have a similar immune response in those over the age of 56 and between the ages of 18-55. It’s believed to be better tolerated in older adults.

What are the required doses?

The dosing is comparable to the Moderna vaccine in that AstraZeneca requires two doses separated by 28 days.

Are there any safety concerns associated with this vaccine?

There have not been any serious safety concerns to report at this time as none of the participants who developed an infection were hospitalized or developed serious diseases.

The phase 3 trial had been temporarily paused (which is common in most clinical trials) to determine the causality of certain neurological symptoms developed in 2 participants. It has since been resumed upon determining there is no causal link between the vaccine and the symptoms based on extensive investigator review.

4.  Johnson & Johnson

Johnson & Johnson’s Janssen vaccine is funded by the U.S government’s Warp Speed. This vaccination has started its phase 3 clinical trial in September of 2020 and has not yet been approved by the FDA.

What is in the vaccine?

Johnson & Johnson’s Janssen vaccine is comparable to the AstraZeneca/Oxford vaccine. Using a weakened adenovirus, this vaccine delivers information about the pathogen to the body in the hopes to activate an immune response. This adenovirus expresses the SARS-CoV-2 spike protein that is also presented in the Covid-19 viral infection. 

How effective is this vaccine?

Due to the late start on their phase 3 trial initiation, compared to that of Pfizer and Moderna, Johnson & Johnson has not yet released much data thus far.

However, their phase 3 trials continue to follow positive interim results. There have been reports of almost all participants developing a strong T cell response to the virus along with some effective neutralizing antibodies after a single dose.

What are the required doses?

Unlike the previous promising vaccinations, the Johnson & Johnson vaccine only requires a single dose. There has been strong efficacy in the trial of a single dose. Hwever, this could change pending the results of a second dose in their ongoing phase 3 trials.

Are there any safety concerns associated with this vaccine?

Any reported adverse events were concluded to be ‘mild’ and ‘moderate’. With an overall 2 adverse events reported in the trials, one of which was unrelated to the vaccination and the other has been deemed ‘suspicious’ with a fever. The second participant has since made a full recovery from their symptoms.