A new study from the Centers for Disease Control and Prevention found that protection from the Moderna and Pfizer coronavirus booster shots wanes after about four months, reinforcing questions about the need for a fourth dose.
The study found that protection against hospitalizations dropped from 91% during the two months after a third dose to 78% four months after the shot. Protection against visits to the emergency department or urgent care declined from 87% to 66% over the same time intervals.
Researchers analyzed more than 240,000 visits to emergency departments or urgent care facilities and over 93,000 hospitalizations across 10 states from August 2021 to January – a time when the highly contagious omicron variant was the dominant strain.
But the study had several limitations, including that researchers couldn’t separate a booster shot from a third dose given to an immunocompromised person and that the research focused on people seeking medical attention, which could skew the data toward older populations or people with weakened immune systems anyway.
Cartoons on the Coronavirus
The finding that the third shot’s protection waned “reinforces the importance of further consideration of additional doses to sustain or improve protection” against hospitalizations and emergency department or urgent care visits, the study’s authors wrote.
Experts agree that a fourth coronavirus shot will likely be needed, but there are varying opinions about when and what kind.
Both Moderna and Pfizer have launched trials for coronavirus vaccines that specifically target the omicron variant, which is responsible for virtually all infections in the U.S. The Moderna CEO last month said a fourth shot may be needed in the fall.
“We are discussing with public health leaders around the world to decide what we think is the best strategy for the potential booster for the fall of 2022. We believe it will contain omicron,” CEO Stephane Bancel told CNBC’s “Squawk Box.”
And Pfizer CEO Albert Bourla said that coronavirus booster shots every four to five months is “not a good scenario” and that he hopes to move to an annual shot instead.