A new study by the US Centers for Disease Control and Prevention (CDC) has said that the efficacy of third doses of the Pfizer and Moderna mRNA vaccines wanes substantially by the fourth month after administration.
Though it is now well documented that vaccine efficacy goes down after two doses, relatively little has been published on the duration of protection after a booster.
The new study was based on more than 241,204 visits to the emergency department or an urgent care clinic, and 93,408 hospitalizations, which are more serious, among adults with Covid-19-like illness from August 26, 2021, to January 22, 2022.
The study reveals that the third dose of mRNA vaccine continues to offer high levels of protection against severe disease, even months after administration, underscoring the importance of staying up to date when eligible after receiving a primary series.
"The finding that protection conferred by mRNA vaccines waned in the months after receipt of a third vaccine dose reinforces the importance of further consideration of additional doses to sustain or improve protection," the authors concluded.
Speaking at a White House Covid-19 briefing on Wednesday, President Joe Biden's top medical advisor Anthony Fauci said it was likely that fourth doses would more likely be needed for subsets of people who mount weaker immune responses, such as the elderly and immunocompromised.
Though it is now well documented that vaccine efficacy goes down after two doses, relatively little has been published on the duration of protection after a booster.
The new study was based on more than 241,204 visits to the emergency department or an urgent care clinic, and 93,408 hospitalizations, which are more serious, among adults with Covid-19-like illness from August 26, 2021, to January 22, 2022.
The study reveals that the third dose of mRNA vaccine continues to offer high levels of protection against severe disease, even months after administration, underscoring the importance of staying up to date when eligible after receiving a primary series.
"The finding that protection conferred by mRNA vaccines waned in the months after receipt of a third vaccine dose reinforces the importance of further consideration of additional doses to sustain or improve protection," the authors concluded.
Speaking at a White House Covid-19 briefing on Wednesday, President Joe Biden's top medical advisor Anthony Fauci said it was likely that fourth doses would more likely be needed for subsets of people who mount weaker immune responses, such as the elderly and immunocompromised.
