Are the booster doses the same as previous COVID-19 vaccines?
Yes, the booster doses use the same recipe as the previous ones, despite the appearance of the more contagious delta variant. The vaccines were not modified to fit delta because they continue to work well.
Vaccines work by training the body to recognize and fight the spicular protein that coats the coronavirus and helps it invade the cells of the body. Fortunately, the delta mutations did not make the virus so different as to avoid detection.
The extra protection you might get from a modified booster dose to better fit a variant would be minimal, said Dr. Paul Goepfert, director of the Alabama Vaccine Research Clinic at the University of Alabama at Birmingham.
Making doses with a new formula would also have delayed the distribution of the boosters.
Moderna and Pfizer are studying booster doses tailored to delta and other variants to be ready if needed. Health authorities would have to decide if and when it would be worth changing the formula.
“What we don’t know,” Goepfert said, “is if you have a delta vaccine, compared to the regular vaccine, does it really work better to prevent contagion or asymptomatic infection?”
The United States has authorized booster doses for Pfizer, Moderna and Johnson & Johnson in some people, and a few other countries use boosters of those drugs or other COVID-19 vaccines.
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