Now that booster doses are rolling out in the country, many people are skeptical about getting additional shots that are different from the main COVID-19 vaccine they had. This is particularly true for those who got the Johnson & Johnson vaccine. But there is evidence that Janssen recipients will actually benefit more from getting Moderna or Pfizer booster doses than the one being offered by J&J and BioNTech.

Janssen Vs. Moderna and Pfizer Vaccines

Before delving deeper into the mixing and matching of vaccines and boosters, it is important to first understand the difference between the Janssen vaccine and the vaccines from Pfizer and Moderna. Janssen is a type of carrier vaccine wherein a harmless adenovirus is engineered to deliver genetic code for spike proteins that will train the body’s immune system on how to respond to an actual SARS-CoV-2 infection.

Unlike the J&J vaccine, the Pfizer and Moderna vaccines are classified as mRNA vaccines. This means that the other two vaccines deliver genetic codes from the SARS-CoV-2 virus itself to the human body, so that cells could make copies of spike proteins that would stimulate an immune response should the recipient be exposed to the actual coronavirus, as explained by Yale Medicine.

J&J’s vaccine was designed to be a single-dose biological preparation, whereas Moderna’s and Pfizer’s vaccines were made to be two-dose preparations. Due to their different formulations, the three vaccines available in the country also have varying efficacy. A comparative report released by the Centers for Disease Control and Prevention (CDC) in September showed that the Moderna vaccine provided 93% protection to adults without underlying conditions, while Pfizer recorded 88% and Janssen reported 71%.

Efficacy Of Janssen Booster

In October, J&J’s vaccine booster was officially given authorization by the U.S. Food and Drug Administration for emergency use. This would mean that those who got their Janssen doses at least two months prior could now get their second dose that’s expected to amplify their immune protection against the novel coronavirus amid the ongoing pandemic.

Prior to the authorization, J&J issued a statement saying that based on its clinical trials, the second Janssen dose does reinforce protection from COVID-19. From the data it collected in the course of the trials, the pharmaceutical company found that the booster offered 100% protection against severe infection and 95% against symptomatic infection in U.S. recipients. The Janssen booster also reportedly produced four to six times higher antibody levels than the main dose if the interval between the two was at least two months. On the other hand, there was a 12-fold increase in antibodies if the interval was at six months.

Mixing and Matching Vaccine Boosters

The FDA and CDC recently recommended the mixing and matching of booster doses among the three brands. What this means is that those who got the Pfizer vaccine can get a booster from Moderna and J&J if the one from Pfizer is not readily accessible to them. The same is true for the other two brands. But considering the variation in the vaccine formulations, many are skeptical about getting a different booster from their main vaccine.

Experts have shared their views on the issue, and most of them said that Janssen recipients could actually benefit more if they were to get their booster from either Moderna or Pfizer. Among them is Donald Alcendor, PhD, an assistant professor of Cancer Biology at Meharry Medical College and adjunct associate professor of Cancer Biology at Vanderbilt University School of Medicine.

“Evidence also suggests that there is a more robust immune response when the second dose for a single-shot J&J vaccine is Moderna or Pfizer-BioNTech. This provides a growing body of evidence that supports the notion that mixing and matching of the J&J vaccine is warranted due the stronger immune response induced by the Pfizer or Modern vaccines as the second component to the J&J single dose,” Alcendor told Contagion.

A study published in medRxiv last month determined the difference in efficacy between homologous and heterologous booster vaccinations using the three vaccine brands. For homologous vaccination (same vaccine and booster), the resulting neutralizing antibody titers increased 4.2-20-fold. On the other hand, for heterogenous vaccination (different vaccine and booster), the titers increased 6.2-76-fold. The findings suggest that getting a different booster for Janssen recipients would lead to a much better outcome.

“I’ve seen the data, and I would hope the (FDA) and the CDC are also impressed with the data. Clearly, if you’ve received the J&J dose and then you received one of the mRNA vaccines, you get a very large boost in antibody—even more antibody than if you got a second dose of J&J,” Vanderbilt University Medical Center Professor of Preventive Medicine William Schaffner, MD, who was not involved in the study, said.