The U.S. Food and Drug Administration (FDA) has authorized a fourth mRNA vaccine dose for all individuals aged 50 and over. The authorization includes both Pfizer and Moderna vaccines and is recommended to be administered at least four months after a third dose.
As the United States continues to experience a downturn in COVID-19 cases and hospitalizations following the sharp Omicron spike at the beginning of the year, epidemiologists are warning of a looming new wave. The Omicron variant BA.2 is rapidly becoming dominant in the US and, as demonstrated in several countries around the world, it has the potential to cause significant new surges in hospitalizations and deaths.
A third mRNA vaccine dose has been shown to be crucial in generating robust protection against the Omicron variant, but that protection has been seen to wane after three to four months. At the end of 2021 Israel began rolling out a fourth vaccine dose to some older or at-risk populations and early data has indicated the extra dose could be helpful for more vulnerable individuals.
“Current evidence suggests some waning of protection over time against serious outcomes from COVID-19 in older and immunocompromised individuals,” said Peter Marks, head of the FDA’s Center for Biologics Evaluation and Research. “Based on an analysis of emerging data, a second booster dose of either the Pfizer-BioNTech or Moderna COVID-19 vaccine could help increase protection levels for these higher-risk individuals.”
The FDA authorization is calling the fourth dose a “second booster,” and is targeting all “individuals 50 years of age and older” who are at least 4 months past their previous vaccine shot. For those under the age of 50 the authorization is much more limited, focusing only on those aged 12 and older with particular medical conditions that leave them in highly immunocompromised states.
“These are people who have undergone solid organ transplantation, or who are living with conditions that are considered to have an equivalent level of immunocompromise,” the FDA authorization stated.
The fourth dose authorization notably cites a lower age cut-off than was expected following a recent application by Pfizer looking only at boosters for those aged over 65 years. In a recent press conference Marks addressed the lower age range by pointing out one in three people between the age of 50 and 65 suffer from pre-existing health conditions that are known to increase their risk of severe COVID-19. So, by authorizing a fourth dose for those 50 and over he hopes to protect a large population of vulnerable individuals in that age bracket.
Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC) echoed Marks’ comments in a statement announcing updated CDC recommendations regarding COVID-19 vaccines.
“Boosters are safe, and people over the age of 50 can now get an additional booster 4 months after their prior dose to increase their protection further,” Walensky said. “This is especially important for those 65 and older and those 50 and older with underlying medical conditions that increase their risk for severe disease from COVID-19 as they are the most likely to benefit from receiving an additional booster dose at this time.”
