By Ethan Covey
The effectiveness of the COVID-19 vaccines currently available in the United States is less against omicron than previous variants, but additional booster doses provide significant protection, according to a CDC report.
The report outlines that the third and fourth booster doses increased vaccine effectiveness (VE) against SARS-CoV-2—including variants and subvariants—in eligible people (MMWR Morb Mortal Wkly Rep 2022;[71]:931-939).
“This study shows the importance of staying up-to-date on COVID-19 vaccines,” said Ruth Link-Gelles, PhD, an epidemiologist on the CDC’s COVID-19 Emergency Response Team, in Atlanta.
The omicron B.1.1.529 variant was first identified in the United States during November 2021, and the BA.1 sublineage soon resulted in a large surge of cases across the country. As of April 2022, BA.2 and BA.2.12.1 became the predominant sublineages in the United States.
An analysis of data from the VISION network of public health records focused on nearly 214,500 emergency department or urgent care visits and more than 58,000 hospitalizations with a COVID-19–like illness diagnosis in 10 states from Dec. 18, 2021 through June 10, 2022.
During the BA.1-dominant period, VE against COVID-19?associated hospitalization seven to 119 days after receipt of dose 3 was 92%, then dropped to 85% on or after day 120 following that dose. While BA.2/BA.2.12.1 dominated, VE fell to 69% and 52%, respectively.
Among individuals 50 years of age and older, after receiving dose 3, VE against COVID-19 hospitalization on or after day 120 was 55%. Following a fourth booster dose, during the period of BA.2/BA.2.12.1 predominance, VE rose in this age group to 80% at least seven days after the shot.
“The findings of this study, in conjunction with recently published data showing people infected with BA.2 may also have antibodies that can protect against illness with BA.5, suggest that currently available vaccines may provide protection against serious illness caused by the currently circulating BA.5 variant,” Dr. Link-Gelles said.
“The bottom line is that if you are eligible for a booster, you should get it immediately and not defer,” she said.
