The COVID-19 Vaccines and the Struggle to Stay Up-To-Date

At a Glance

In the US, there are currently three vaccines for COVID-19 authorized as of this writing, March 4th, 2021, with two in Phase 3 clinical trials or awaiting emergency approval. Right now, new information on vaccines is becoming available on a daily, and sometimes hourly, basis.  Here’s what you should know about each.

Authorized Vaccines

Pfizer/BionNTech BNT162b2

  • 95% effective when dosing schedule is correctly followed.
  • mRNA-based vaccine.
  • Recommended for people 16 years and older.
  • Two-dose vaccine, 21 days apart between doses.
  • Injected intramuscularly, usually in the upper arm.
  • Does not contain eggs, preservatives, or latex.

Moderna mRNA-1273

  • 94.1% effective when dosing schedule is correctly followed.
  • mRNA-based vaccine.
  • Recommended for people 18 years and older.
  • Two-dose vaccine, 28 days apart between doses.
  • Injected in the upper arm.
  • Does not contain eggs, preservatives, or latex.

Janssen/Johnson & Johnson

  • 85% effective against severe/critical COVID-19 cases, 66% effective against mild or moderate cases.
  • Adenovirus-based vaccine.
  • Recommended for people 18 years and older
  • One-dose vaccine.
  • Injected intramuscularly.

What Does “Effective” Mean?

Any discussion of vaccine efficacy (how effective it is) must also disclose what the end goal of the vaccine is.  With COVID-19 vaccinations, the end goals of the vaccines are to prevent serious illness, hospitalization, or death.  It is worth noting that it is still not known whether vaccinated individuals can contract and/or spread the virus. More clarity on this will come as more become vaccinated and as more scientific study is performed.

The crucial data point, from a public health perspective, is the reduction of hospitalizations and deaths. For example, in the Phase III trials of the Pfizer vaccine, out of 21,720 who received the vaccine and 21,728 who received the placebo in the control group:


  • After the first dose, there were ten confirmed serious cases of COVID-19, one of which was in the vaccine group, while the other nine were in the control group.
  • After the second dose, there were eight cases of serious COVID-19 illness in the vaccine group, compared to 162 in the control group. 

Fortunately, there were no deaths in the trial. 

When assessing vaccines, look for the study data and discuss it with a medical professional. 

What Are mRNA Vaccines?

Messenger RNA (mRNA) vaccines teach cells to make a specific protein that triggers an immune response. A good analogy is that it faxed a wanted poster to your immune system, which memorizes it, and then destroys the poster.  Both the Pfizer and Moderna vaccines are mRNA vaccines.

What Are Adenovirus-Based Vaccines?

Many vaccines use a “knocked-down” version of a common virus as a vector to introduce genes as antigens to the immune system, allowing the immune system to develop antibodies against that antigen. In this case, the vaccine uses an adenovirus as a vector to instruct cells to make the “spike protein” that’s a distinctive aspect of the COVID-19 virus.  

Will A Vaccine Reduce or Prevent Transmission?

It is not yet clear if the vaccine helps reduce the chances of transmission, so current social distancing, mask wearing, and cleaning protocols should be followed.

Who Is Prioritized To Receive a Vaccine?

Vaccine programs vary from state to state. As of this writing, 3/4/2021, the CDC’s recommendations prioritize health care workers; essential personnel; anyone 65 or older; and anyone 16 or older with at least one underlying chronic medical condition that may increase the severity of COVID-19 infection.  Just yesterday, 3/2/2021, the federal government directed states to prioritize primary school teachers for vaccination, and several states have already responded to this directive.

Vaccines In Clinical Trials

There are also two vaccines in Phase 3 clinical trials, from AstraZeneca and Novavax. These trials are testing the safety and efficacy of the vaccines in a large-scale human population.

  • The Oxford-AstraZeneca is an adenovirus-based vaccine. Novavax uses a stabilized form of the “spike” protein found in the virus to stimulate an immune response.
  • The Oxford-AstraZeneca vaccine has been put into emergency use in the United Kingdom, but as of this writing has not been authorized by the FDA. AstraZeneca expects to request emergency authorization in early 2021.
  • Both the AstraZeneca vaccine and Novavax require two doses, 28 days apart and 21 days apart respectively.
  • The Oxford-AstraZeneca vaccine has also been submitted for an emergency approval.
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