Americans who received Johnson & Johnson's single-shot COVID-19 vaccine are less protected against serious illness and hospitalizations than those who received an mRNA vaccine, and should likely consider getting a booster dose of either Pfizer's or Moderna's vaccine, according to new Centers for Disease Control and Prevention (CDC) data released Tuesday.
Researchers found that one Johnson & Johnson dose was 24 percent effective at preventing virus-related emergency department or urgent care visits, while two Johnson & Johnson doses were 54 percent effective compared to 79 percent after one Johnson & Johnson dose and one dose of either of the mRNA vaccines.
Three mRNA vaccine doses provided 83 percent effectiveness at preventing virus-related emergency department or urgent care visits, researchers said.
The researchers also found that two Johnson & Johnson doses were 67 percent effective at preventing virus-related hospitalization, compared to 78 percent after one Johnson & Johnson dose and one dose of either of the mRNA vaccines, based on data from 25,244 hospitalizations among patients with COVID-like illness.
Three mRNA vaccine doses provided 90 percent effectiveness at preventing hospitalizations, the CDC said.
Based on the data, the CDC recommends that patients mix and match vaccine types in order to be better protected against COVID-19.
Researchers noted that recommendation is being made "in light of the risks for rare but serious adverse events following receipt of a Janssen vaccine, including thrombosis with thrombocytopenia syndrome and Guillain-Barré syndrome."
Guillain-Barré syndrome is a rare but severe autoimmune disorder that can cause paralysis and occurs when an individual's immune system damages the nerves, in turn causing muscle weakness.
"These findings underscore the importance of receiving recommended COVID-19 booster doses, when eligible, to prevent moderate to severe COVID-19 during Omicron variant predominance," researchers wrote.
"Adults who received a Janssen vaccine as their first dose should preferentially receive a heterologous mRNA vaccine booster dose 2 months later, or a homologous Janssen vaccine booster dose if mRNA vaccine is contraindicated or unavailable," researchers added.
However, researchers acknowledged limitations in their findings, most notably that the research took place over a limited period of time and involved monitoring patients for 120 days at most.
"Thus, the observed effectiveness of these strategies is limited to a relatively short period after vaccination," researchers wrote.
Additionally, the small number of participants in the study who had received Johnson & Johnson’s vaccine "reduced the precision of VE estimates across both primary series and booster strategy groups" and also made it difficult to break down vaccine effectiveness according to demographic factors such as age and race, "or assessment for potential effect modification due to underlying conditions, including immunocompromise."
"Third, although adjustments to account for differences between unvaccinated and vaccinated persons were made, they did not account for differences among persons vaccinated with different strategies," researchers noted.