The 3 COVID-19 Vaccines

We are now one year into the SARS-CoV-2 pandemic that has taken the lives of many Americans and millions of people around the world.  When the pandemic first began, we knew that we could minimize spread by physical distancing, hand washing, and wearing facemasks, but in order to truly minimize hospitalizations and deaths, a vaccine would need to be developed.

Thankfully, we now have many vaccines that show they are effective against the virus, and we have 3 here in the United States that have been approved by the Food and Drug Administration (FDA).  The vaccines that have been approved for Emergency Use Authorization (EUA) by the FDA are:

• • • Pfizer: mRNA vaccine
    • Moderna: mRNA vaccine
    • Johnson & Johnson: vectored vaccine

COVID fatigue is very real and many people would like to have life return to “normal”.  This is not possible until the majority of the population has been vaccinated, or have had a primary infection (which we want to prevent), so that we can achieve a level of herd immunity.  Even once this is achieved, the virus will still exist but the risk of infection will be lower, and hopefully we can avoid severe infections requiring hospitalization. The emergence of new variants around the world, and now in the US, was worrisome for the possibility of increased contagiousness and possibly severe infection.  Thankfully, it appears that the available vaccines have activity against the new variants. This is another reason why vaccination is so important.  I recommend that you do not wait for a particular vaccine, just get vaccinated.  All three vaccines available to us in the US show high efficacy rates in preventing symptomatic SARS-CoV-2, something that is not always seen with seasonal influenza vaccines.

Here is a summary of how these types of vaccines work:

• • • mRNA vaccines:
      • • mRNA vaccines have messenger RNA (mRNA) that is surrounded by a nanoparticle.
        • Once the mRNA reaches the cell, the mRNA is used to make proteins, specifically the protein spike antigen.
        • After the protein is made, it is expressed by the cell, which triggers your immune system to make antibodies against the protein.
    • Vector vaccines:
      • • Vectored vaccines use a vector, either a plasmid or some non-pathogenic organism.
        • The genes of the virus, specifically the proteins of the spike protein, is inserted into the genome of the vector.
        • Once the vaccine is given, the vector is taken up by the cell and proteins are made from the genetic material.
        • After the protein is made, it is expressed by the cell, which triggers your immune system to make antibodies against the protein.

Here is a summary of the data from the available vaccines in the US:

• • • Pfizer:
      • • mRNA vaccine
        • Received its EUA in December 2020, making it the first COVID-19 vaccine authorized in the US
        • It has been approved for individuals 16 years of age and older
        • 2 doses, given 3 weeks apart
        • Efficacy of 95% for prevention of symptomatic SARS-CoV-2 infection
    • Moderna:
      • • mRNA vaccine
        • Received its EUA in December 2020, making it the second COVID-19 vaccine authorized in the US
        • It has been approved for individuals 18 years of age and older
        • 2 doses, given 4 weeks apart
        • Efficacy of 94% for prevention of symptomatic SARS-CoV-2 infection

These vaccines CANNOT be used interchangeably (there is currently no data supporting this). Whichever vaccine you receive first, you should complete the series with that vaccine.

• • • Johnson & Johnson:
      • • Adenovirus vectored vaccine
        • Received its EUA on February 27, 2021, making it the third COVID-19 vaccine authorized in the US
        • It has been approved for individuals 18 years of age and older
        • One dose only
        • Efficacy of 66% in the prevention of symptomatic SARS-CoV-2 infection
        • Efficacy of 76-85% in prevention of SEVERE/critical SARS-CoV-2 infection at 14 and 28 days post vaccination, respectively.
        • Additional analysis is currently looking whether this vaccine may have efficacy in preventing ASYMPTOMATIC SARS-CoV-2 infection (no symptoms but positive test, either by PCR or rapid antigen).
          • • Preliminary data revealed an efficacy of 59% in possibly preventing asymptomatic infections 29 days after vaccination.
            • This data has yet to be analyzed and peer reviewed.

I urge you to get vaccinated when you are able to, but I also ask that you continue to use the measures that we know work.  A year into this pandemic, we can finally start to see “the light at the end of the tunnel”, but this pandemic is far from over.  Let’s not let our guard down yet; continue to physical distance, avoid crowded places, wear a facemask, and wash your hands regularly.  We have come this far, let’s not take a step back!