The emergence of the Delta variant represented an unexpected obstacle for COVID-19 vaccines. While it was initially reported that the vaccines are also effective against the new variant, it appears that the effectiveness decreases in time. The Delta variant has now become the dominant strain of COVID, and it is responsible for the majority of cases in the United States.
Unfortunately, the Centers for Disease Control and Prevention discovered that the protection offered by COVID-19 vaccines against the new strain is decreasing. Before the apparition of the Delta variant, vaccines had an effectiveness of 91%, which has now decreased to 66%. Nevertheless, despite this lower rate of efficiency, this number continues to represent significant protection for those vaccinated.
The new CDC study used data from 4000 health care workers, and it was conducted between December 2020 and August 2021. Researchers also believe that the time that has passed since vaccination might also represent a factor in the decrease of effectiveness. Another study from CDC analyzed the rate of hospitalizations as well, comparing unvaccinated and vaccinated persons from Los Angeles in order to determine whether the vaccine impacts the severity of the disease. It was found that 71.4% of those hospitalized were unvaccinated, 25.3 were fully vaccinated, and 3.3% were partially vaccinated. According to the numbers, the rate of infection for people who had not taken the vaccine was almost five times larger than the one of those vaccinated. In comparison, the hospitalization rate was almost 30 times bigger.
“These infection and hospitalization rate data indicate that authorized vaccines were protective against SARS-CoV-2 infection and severe COVID-19 during a period when transmission of the delta variant was increasing. Efforts to increase COVID-19 vaccination, in coordination with other prevention strategies, are critical to preventing COVID-19-related hospitalizations and deaths,” reads the study.