A Danish study published yesterday indicates that receiving a third dose of the Pfizer or Moderna COVID-19 vaccines "significantly increases" the effectiveness of these vaccines in preventing the Omicron variant among the elderly. The study, which has not yet been peer-reviewed, focused on the effectiveness of mRNA-based COVID-19 vaccines against the more prevalent Delta and new Omicron variants.
The researchers wrote in the study, "Our results support emerging evidence that the initial protection of the Pfizer-BioNTech and Moderna vaccines against Omicron decreases rapidly over time, with a significant increase in protection observed after receiving a booster dose." The study was conducted by researchers at the Statens Serum Institute, Denmark's leading authority on infectious disease control. They analyzed data collected between November 20 and December 12 from three million citizens in Denmark.
After receiving a second dose of either vaccine, the Pfizer-BioNTech vaccine showed an effectiveness of 55.2% against Omicron compared to 36.7% for the Moderna vaccine, when compared to individuals who had not received any vaccination. However, the researchers noted that the protection provided by both vaccines diminished quickly over five months.
Nevertheless, a third dose of the Pfizer-BioNTech vaccine restored the level of protection to 54.6% among individuals aged 60 years and older who were vaccinated 14 to 44 days prior, compared to those who received only two doses.
