The Effectiveness of the Pfizer and Moderna Vaccines: A Review of the Research

As we have been faced with a global pandemic for over a year, several countries now have COVID-19 vaccination programs in full gear. In the United States, we are vaccinating about 4 million persons a day. The two primary vaccines currently being used are the Pfizer BioNTech (Pfizer) and the Moderna vaccines.

Understandably, the level of protection afforded by the vaccines against COVID-19 and existing (or emerging) variants is widely being studied as we seek to decrease deaths, severe illness and restore the economy and vestiges of our former lives.

Preliminary research based on clinical trials and real-world studies has indicated that both the Pfizer and Moderna vaccines are highly efficacious and safe. Below we will share information about the two vaccines and their effectiveness.

The Vaccines Explained

Pfizer and Moderna are mRNA vaccines, and they both require two doses at different intervals to achieve optimal protection. Essentially, the vaccines work by telling the body to make a specific spike protein that trains the immune system to recognize it. If the person’s body is infected with the virus, the immune system will, in a sense, ‘remember’ the protein and attack it.

Prevention at a Glance

When it comes to preventing infection for those who have not been previously infected, the Pfizer and Moderna vaccines boast effectiveness of 95% and 94.1%, respectively, among those of varying age, sex, race, and ethnicities. And in studies under real-world conditions, mRNA vaccines showed 90% effectiveness against COVID-19 fourteen or more days after the second dose. This is excellent news, but as indicated above, there are multiple layers of protection that are of interest regarding both vaccines. As such, we will further analyze the research to get a fuller picture of the protections they each provide.

The Vaccines Compared

As previously mentioned, both vaccines are safe and effective. But what and how much does each vaccine protect against?


Preventing COVID-19

  • After at least seven days after the second dose, the vaccine was 95% effective.
  • From seven days up to 6 months after the second dose, the vaccine was 91.3% effective.
Protection after one dose

Israeli study:

  • 46% effective at ‘preventing a confirmed infection’ and 57% effective in ‘preventing a symptomatic infection’ 14 to 20 days after first dose.
  • Regarding preventing hospitalizations and severe disease, the vaccine was 74% and 62% effective, respectively, 14 to 20 days after the first dose.

Recent CDC study:

  • Showed both mRNA vaccines were 80% effective at preventing COVID-19 fourteen or more days after the first dose (but before the second dose).

Preventing hospitalizations and death

  • 100% effective in preventing ‘severe disease’ as defined by the CDC and 95.3% effective at preventing ‘severe COVID-19’ as defined by the FDA.

Protection against variants

  • 100% protection against the South African variant (1.351).
  • Early reports suggest that the vaccine is also effective against the UK variant (B.1.1.7).

Preventing COVID-19

  • At least 14 days after the second shot, the vaccine was 94.1% effective in preventing the virus.

Protection after one dose

  • As reported above, mRNA vaccines showed an 80% effectiveness in preventing disease fourteen or more days after receiving the first shot, but before the second shot.

Preventing hospitalizations and death

  • Clinical trials revealed an 89% effectiveness in preventing hospitalizations. The one research participant who died during the study was in the placebo group.

Protection against variants

  • Clinical evidence has not yet been reported on the vaccine’s protection against the variants. However, Moderna has indicated that the vaccine is effective against both the UK and South Africa variants, although there is less protection against the South Africa variant. Research is continuing in this area.

At Healthcare Solutions Team, we are committed to your well-being including keeping you informed about relevant healthcare matters. To learn more about the COVID-19 vaccines or your health coverage options, contact us today to speak to one of our knowledgeable agents.

Healthcare Solutions Team is a wholly owned subsidiary of the National General Insurance Group and the Allstate Insurance Company.