A third COVID-19 vaccine by Johnson & Johnson could be on the horizon, but while it could be beneficial to those who aren’t comfortable with the two doses needed by the Pfizer/BioNTech and Moderna vaccines, there is one major issue with the newest one to potentially hit the market—its efficacy rate.

Following global clinical trials, the vaccine was proven to be 66% effective at preventing moderate and severe illness from COVID-19, according to The Washington Post. The trial found 85% efficacy at preventing severe disease overall and 72% effectiveness at preventing moderate to severe illness in the United States, but in areas where troubling new variants of the disease have emerged, the rate was much lower—showing only 66% effectiveness in Latin America and 57% in South Africa.

For comparison, the flu vaccine is usually only 50% effective against influenza B viruses and 37% effective against influenza B viruses, according to the CDC.

Despite having a lower rate than both the Pfizer and Moderna shots, which both have a rate of over 90%, it is expected that the company will file for Emergency Use Authorization with the FDA next week, meaning, if approved, it could be available to the public by late February or early March. The minimum requirement the FDA has for vaccines to be approved is at least a 50 percent efficacy rate.

However, while the shot is considered to be less effective than its counterparts, there are other advantages to the potential third vaccine, including the fact that those who are administered it only need one dose, which could help streamline vaccination efforts and mean more doses are available to more people, versus the two-shot system which winds up in fewer arms. Jonathan Temte, a vaccine expert at the University of Wisconsin School of Medicine and Public Health also noted to WaPo that this one could be stored for months at a refrigerated temperature, unlike its competitors which need to be kept in ultracold or freezing temperatures, another complication which has effected rollout.

The company also reports that similar to its competitors, no major side effects are expected for those who receive the shot, with some reporting fevers. No one in the 44,000 person trial experienced anaphylaxis, which did previously affect the distribution of the Moderna vaccine when a lot in California seemed to cause severe allergic reactions in multiple people.

If approved, the company has an agreement with the government to deliver 100 million doses to the United States by the end of June.

The newest vaccine comes as concerns have grown about the other ones on the market, especially with the newly emerging South African and UK strains that are more contagious. Dr, Anthony Fauci already warned the public that while the vaccines still have a good efficacy rate against variants like B-117 and 501Y.V2, the vaccines were less effective against those.

Johnson & Johnson Vaccine Vials of a COVID-19 Vaccine are pictured with the logo of US pharmaceutical company Johnson & Johnson on November 17, 2020. Photo: Justin Tallis/AFP via Getty Images