Written by: Esha Kataria ’24
Edited by: Raymond Del Vecchio ’24
On February 27, the FDA approved a third vaccine for COVID-19, a single-shot dose by Johnson & Johnson (J&J). The J&J vaccine has its differences from the Modern and Pfizer vaccines, both biologically and logistically. This article will explore those differences while maintaining that no one vaccine is better than the other; they all provide the same protection and thus, we must not discriminate between them.
The mechanisms behind the Moderna and Pfizer vaccines are different from the J&J vaccine. The Moderna and Pfizer vaccines use messenger RNA, single-stranded genetic material used in the synthesis of proteins, to fight the virus. This genetic material gets taken up by cells in the injection site, which use the RNA to make tiny pieces that resemble the coronavirus. These proteins stimulate an immune response by generating antibodies, proteins that detect harmful substances, and immune cells that are ready to attack upon infection. On the other hand, the J&J vaccine uses viral vector technology. A common cold virus called adenovirus 26 is genetically engineered and used to infect cells without spreading/replicating throughout the body. Instead, this virus carries genetic information in the form of DNA to arm cells, which are instructed to make pieces of the coronavirus spike protein, or what the coronavirus uses to connect to cells. By making this spike protein, the vaccine triggers an immune response in the cells so the immune system can react more strongly to the spike proteins in the future. This protects us from getting sick from COVID-19.
Another way J&J vaccine differs from Moderna and Pfizer is that the former requires one dose, while the latter two require two doses. This means that the J&J vaccine provides ample protection with just one shot, making it logistically easier to distribute and supply, allowing for quicker protection against COVID-19. Further, it doesn’t require an abnormally low temperature to be shipped and stored. While the Pfizer vaccine must be stored and shipped at between -80ºC to -60ºC, and the Moderna vaccine requires a temperature of -20ºC, the J&J vaccine can be stored at refrigerator temperatures for up to three months, makings it much easier to store and ship.
Finally, the J&J vaccine was 66% effective against moderate to severe illness, and 85% effective against severe disease, while the Moderna and Pfizer vaccines showed efficacy rates closer to 94% and 95%. This is because the J&J study took place in a different place and time; testing vaccines in different locations and during different stages of the pandemic has affected the efficacy results as mutations to the virus have given rise to more contagious variants unique to location. The J&J vaccine was tested in 44,000 people in the US, South Africa and Latin America, and took place during the later months of the pandemic. In contrast, the Moderna and Pfizer vaccines tested in the spring and summer of 2020. Pfizer's vaccine was tested in 43,000 people in the US, Germany, Argentina, South Africa, Turkey, and Brazil. Moderna's vaccine was tested in 30,000 people, all of whom were in the US. The J&J vaccine was tested when some of the variants of COVID-19 started to circulate, such as the South African variant. Interestingly, the vaccine’s efficacy in South Africa where the variant was dominant was 57%, whereas in the US where the variant wasn’t circulating, it was 72%. This explains why the J&J vaccine showed lower overall efficacy. This might make it seem that J&J is a second-class vaccine or a worse option than the Moderna or Pfizer vaccines. But experts say this is simply not true. UCSF Epidemiologist Dr. Kirsten Bibbins-Domingo said that “When we look at the thing we probably care about the most, making sure that we don’t end up in the ICU or dying, the efficacy of the three vaccines is virtually identical.” Moreover, infectious disease expert Cassandra Pier said that if given the option to choose between the three vaccines she “would choose any of the three, because I know they will work, they will protect me and my family.”
It is clear that while the J&J vaccine is different from the other two, it is still highly effective at preventing severe disease, hospitalizations, and 100% effective at preventing death. Thus, NPR host Maria Godoy concludes that “the best vaccine is the one you are offered first because that’s the one that’s going to protect you the soonest.” Finally, it is important to remember that vaccines prevent contraction but not transmission. While taking the vaccine makes you less likely to get severely ill from COVID-19, it does not mean you can’t spread it to others. Thus, we must remain vigilant in mask-wearing and social distancing as we slowly return to normalcy through mass vaccination.
“Weekend Edition Saturday for March 6, 2021.” NPR, NPR Up First, 6 Mar. 2021, www.npr.org/programs/weekend-edition-saturday/2021/03/06/974339234/weekend-edition-saturday-for-march-6-2021.
“Johnson & Johnson COVID-19 Vaccine Authorized by U.S. FDA For Emergency Use - First Single-Shot Vaccine in Fight Against Global Pandemic.” Content Lab U.S., Johnson & Johnson, 2021, www.jnj.com/johnson-johnson-covid-19-vaccine-authorized-by-u-s-fda-for-emergency-usefirst-single-shot-vaccine-in-fight-against-global-pandemic.
Fox, Maggie. “How J&J's Coronavirus Vaccine Is Different from the Others.” CNN, Cable News Network, 1 Mar. 2021, www.cnn.com/2021/02/27/health/johnson-johnson-coronavirus-vaccine-explainer/index.html.
Corum, Jonathan, and Carl Zimmer. “How the Johnson & Johnson Vaccine Works.” The New York Times, The New York Times, 18 Dec. 2020, www.nytimes.com/interactive/2020/health/johnson-johnson-covid-19-vaccine.html.