(The Hill) — A new study shows high levels of coronavirus antibodies that fight the omicron variant four months after a third dose of the Pfizer vaccine, a positive sign for the durability of a booster shot’s effectiveness.  

The study from researchers at Pfizer, BioNTech and the University of Texas Medical Branch shows virus-fighting antibodies enduring four months after the third dose, helping answer the key question of how long protection from the booster shot lasts.  

Eric Topol, professor of molecular medicine at Scripps Research, tweeted in response to the study that antibody levels were “unexpectedly still quite high” after four months, “which is great.” 

There was still some decline in antibody levels between one month and four months after the third dose, but the amount of decline against omicron was similar to that against the original strain of the virus, Pfizer said.  

Pei-Yong Shi, one of the authors of the study at the University of Texas Medical Branch, told The Washington Post that the study “shows that at least up to four months, post-dose three, there is still substantial neutralizing activity against omicron.” 

The results add to a growing body of evidence on the importance of booster shots, which health officials are urging people to get in the face of a surge from the omicron variant.  

Last week, a Centers for Disease Control and Prevention study found that a third shot was 90% effective against hospitalization, compared to just 57% effectiveness against omicron for someone who is six months past their second shot.  

“Protection against infection and hospitalization with the omicron variant is highest for those who are up to date with their vaccination, meaning those who are boosted when they are eligible,” CDC head Rochelle Walensky said last week. “There are still millions of people who are eligible for a booster dose and have not yet received one.” 

There is still an open question as to how long protection from a booster shot will last beyond four months. That information would help inform whether and when a fourth shot might be needed.  

Pfizer said Monday it would be evaluating “an additional dose of both the current formulation and an omicron-based vaccine,” going forward.