Over the last year, health experts have been studying the effectiveness of the COVID-19 vaccines.

Real-world evidence showed the vaccines offered outstanding protection against COVID-19.

Vaccine effectiveness does wane with time, however, and is not as strong against the delta variant. While breakthrough infections became more frequent in some vaccinated people, the vaccine still provides strong protection against severe infection requiring hospitalization. For those over age 65, there is a slight decrease in protection against severe infection.

Health experts found the slightly waning immunity combined with the emergency of the highly contagious delta variant provided less protection against infection or mild illness.

Does the booster availability mean the vaccines don’t work?

No. In fact, the boosters are intended to better protect those with weakened immune systems (from disease, treatment or age), and decrease the likelihood of infection or mild illness in healthy people that could result from increased exposure to the contagious delta variant. Even without the boost, all the COVID-19 vaccines provide strong protection against hospitalization and death.

In October 2021 the Centers for Disease Control and Prevention (CDC) authorized booster shots of Pfizer, Moderna and Janssen (J&J), and approved mixing vaccine boosters — for instance, someone who received a shot of J&J could get a booster shot of Moderna. Now everyone ages 16 and older can get a booster shot.

A booster dose of the Moderna or Pfizer vaccine, given six months after the primary series, elicits a much stronger immune response with antibody levels several fold higher against the delta variant. This results in much better protection against infection across all ages and a much lower chance of needing hospitalization for older age groups. In the U.S., two doses of the Janssen (J&J) vaccine, given more than two months apart, had an efficacy of 94% in preventing symptomatic infection, compared to one-dose that was 70% effective.

Medical experts are learning more about COVID-19 and how the vaccines work in real time. With more time and study, they will better understand what is necessary to maintain immunity.

Other vaccines, such as polio, HPV, MMR (measles/mumps/rubella) and Tdap (diphtheria/tetanus/pertussis – adults should get a booster dose of Tdap every 10 years) require multiple doses to be effective.

Who should get a COVID-19 vaccine booster shot?

The CDC recommends everyone age 16 and older should get a booster shot. 

Which booster shot should you get?

For adults age 18 and older, any of the COVID-19 vaccines authorized in the United States can be used for the booster dose: Pfizer, Moderna or Janssen (J&J). Children age 16 and 17 may get a Pfizer booster.

When should you get a booster shot?

You can get a booster if it's been at least 6 months since you completed your two-dose primary vaccination series with Pfizer or Moderna, or if it's been at least 2 months since you completed your single-dose primary regimen with Janssen (J&J). 

Still have questions about a COVID-19 booster shot?

If you have questions about whether you should get a COVID-19 vaccine booster dose, ask your doctor.

Everyone age 5 and older is recommended to get vaccinated with the primary series, and everyone age 16 and older can now get a booster shot.

Haven’t been vaccinated yet? To date, 185 million people in the U.S. have been fully vaccinated against COVID-19, under the most intense safety monitoring in U.S. history. The evidence is clear and straight-forward. The best way to protect yourself from possible severe illness, long-term health consequences of infection, hospitalization or death is to get vaccinated.

Edward-Elmhurst Health has COVID-19 vaccine appointments available to ages 5 and older, including booster shots for ages 16 and older. It is easy to schedule a vaccine appointment. You do not need a MyChart account. Schedule your COVID-19 vaccine now.

The information in this article may change at any time due to the changing landscape of this pandemic. Read more about COVID-19.