Summary
In this post from Waning efficacy of COVID mRNA vaccines @ יואל קסלר .com we present new data published from the Centers of Disease Control on the waning of efficacy of COVID 19 mRNA vaccines. It is widely known that the mRNA vaccines for COVID 19 showed excellent efficacy against infection initially but that the efficacy may wane after an extended period of time. As a result many health authorities around the world endorsed a booster dose of the vaccine during the wave of the Delta variant of COVID 19 during 2021.
What is already known about this topic?
Protection against COVID-19 after 2 doses of mRNA vaccine wanes and as a result many health authorities and regulatory bodies recommended a booster, third dose of the vaccine. Data published during the Delta wave variant spread showed that this booster was effective in preventing both infection as well as severe manifestations of the disease.
However, there is a significant body of evidence however that the vaccine may be less effective against the Omicron variant of COVID 19, and some have called for a 4th dose booster, but little is known about durability of protection after 3 doses.
What is added by this report ?
Vaccine effectiveness (VE) against COVID-19–associated emergency department/urgent care (ED/UC) visits and hospitalizations was higher after the third dose than after the second dose but waned with time since vaccination. During the Omicron-predominant period, VE against COVID-19–associated ED/UC visits and hospitalizations was 87% and 91%, respectively, during the 2 months after a third dose and decreased to 66% and 78% by the fourth month after a third dose. Protection against hospitalizations exceeded that against ED/UC visits.
What are the implications for public health practice?
All eligible persons should remain up to date with recommended COVID-19 vaccinations to best protect against COVID-19–associated hospitalizations and ED/UC visits.
