New data on the omicron variant wave is seemingly casting doubt on the efficacy of the Johnson & Johnson vaccine after recording more deaths than the mRNA vaccines from Pfizer and Moderna.

COVID Deaths In Janssen Recipients

Recently published numbers from the Centers for Disease Control and Prevention (CDC) suggested that COVID-related deaths among Janssen recipients rose during the omicron wave. For the week of January 8, a rate of more than 5 deaths out of every 100,000 was recorded among people vaccinated with J&J’s vaccine.

On the other hand, the public health agency recorded a rate of around 2 deaths per 100,000 among people jabbed with Moderna and Pfizer vaccines. Meanwhile, a rate of 20 per 100,000 was recorded among unvaccinated Americans in the same period.

The agency also found that those who received the Janssen vaccine as their initial dose and got boosted with the mRNA vaccines also recorded higher rates of COVID deaths during the omicron wave than those who started their vaccination with Pfizer and Moderna vaccines.

Janssen Efficacy Against Hospitalization

In the U.S., around 17 million people got vaccinated with J&J’s vaccine even though previous studies suggested that it was less effective than its Pfizer and Moderna counterparts. Janssen reportedly provided less protection than the mRNA vaccines, but J&J maintained that based on its own studies, its vaccine offered more “durable” protection than its rivals.

A recently published study from J&J scientists found that Janssen’s effectiveness against COVID-related hospitalization was 81% through the delta wave, and it was notably “stable for at least 180 days after vaccination.”

The findings coincided with what researchers in New York discovered after comparing the effectiveness of the viral vector vaccine and its mRNA competitors. According to the researchers, the protection afforded by the mRNA vaccines waned over time, while the protection provided by the Janssen vaccine did not.

Different Immune Response

There is a big difference in how the Janssen vaccine works against SARS-CoV-2 compared to the mRNA vaccines from Pfizer and Moderna. This is due to the different mechanisms they trigger. Janssen uses a weakened adenovirus to stimulate an immune response, while the mRNA vaccines transport a molecule called messenger RNA to stimulate antibody production.

“The J&J vaccine is different in that, initially the antibody responses are quite a bit lower than the mRNA vaccines. But those responses actually are maintained very well over time, even increase a little bit,” Dr. Dan Barouch, the director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, explained to CBS News.

In a study conducted last year, Barouch and his team found that the Janssen vaccine triggered bigger increases in T cells. Such an immune response typically kicks in after infection and plays an important role in offering protection against severe disease, “particularly with variants that largely escape antibodies,” said Barouch.