All vaccines still seem to provide a significant degree of protection against death risk or serious illness but they are less effective at preventing breakthrough infection.
mRNA vaccine against Breakthrough Infections
A target trial emulation study discovered that in an aged population of US veterans with a high comorbidity burden, mRNA vaccine efficiency at preventing COVID-19 infection was significantly lower than previously reported, while effectiveness against mortality was quite high.
These findings imply that, even with vaccination, breakthrough infection mitigation actions are still necessary for pandemic control. The findings were published in Annals of Internal Medicine.
The real-world effectiveness of the Moderna or Pfizer-BioNTech COVID-19 mRNA vaccines in ethnically and racially varied groups across the United States remains unknown, particularly in more vulnerable populations such as the elderly with a high comorbidity burden.
An observational study was set up by researchers from the Veterans Affairs Puget Sound Health Care System and the University of Washington School of Medicine to mimic a target trial of COVID-19 vaccine versus placebo.
Among the more than 5 million people receiving care in the Veterans Affairs health care system, those who received at least one dose of the Moderna or Pfizer–BioNTech COVID-19 vaccine from 11 December 2020 to 25 March 2021 (n = 2,099,871) were matched to unvaccinated controls in a 1:1 ratio based on demographic, clinical, and geographic characteristics.
During a seven-day follow-up that ended on June 30, 2021, the researchers discovered that vaccine efficiency was 69 percent for SARS-CoV-2 infection and 86 percent for SARS-CoV-2–related death. Vaccine effectiveness did not drop when the follow-up period was extended from March 31 to June 30, 2021.
Vaccine efficacy against SARS-CoV-2 infection declined as age and comorbidity burden increased. These findings, according to the researchers, imply that protection against COVID-19 infection, even among vaccinated persons, will necessitate a continuous focus on further mitigation methods.
Image Credit: Getty