To learn more about this evolving issue, Health Matters spoke with Dr. Sharon Chacko, medical director of COVID-19 immunizations in the Division of Community and Population Health and an assistant professor of medicine at Columbia University Vagelos College of Physicians and Surgeons, about vaccine immunity and the recommendation for booster shots amid Omicron.
Health Matters: What do we know about how long immunity lasts after vaccination for COVID-19?
Dr. Chacko: We know that vaccines provide strong protection against severe disease, hospitalizations, and death. Health officials continue to monitor data, and with the rise of variants — such as the highly contagious Omicron variant — they are keeping a close eye on breakthrough infections and waning immunity. Because immunity after vaccination may decrease over time, the CDC now recommends boosters for everyone over 12 years old.
The CDC just published data that shows that getting a Pfizer or Moderna booster after completing a primary mRNA COVID-19 vaccine series was 90% effective at preventing hospitalizations when Omicron was the dominant variant. In comparison, getting two shots was 57% effective when it had been at least six months past the second shot. Another large study that was published in the Journal of the American Medical Association (JAMA), showed that a booster shot helped prevent symptomatic infection from Omicron. That study found that the odds of developing a symptomatic infection were 66.3% lower for people who were boosted compared to those who had received only two shots.
With Omicron, many more people have experienced breakthrough infections. Does that mean vaccines aren’t working?
While Omicron is more transmissible and is responsible for more breakthrough infections than any other variant, a breakthrough infection doesn’t mean that the vaccine isn’t working. In fact, for most people who are vaccinated and boosted, the symptoms are typically very mild. This emphasizes the importance of vaccination and boosters to prevent severe illness and hospitalizations.
Will we need boosters annually?
Currently, we don’t know how often boosters will be needed, but researchers are closely monitoring this question.
What do we know for sure?
Here’s what we know: