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COVID-19 Resources

Six Things You Should Know About COVID-19 Boosters and Additional Doses

Oct. 5, 2021

On Sept. 24, the FDA, CDC and Advisory Committee on Immunization Practices approved emergency use authorization (EUA) for our nation’s first COVID-19 booster vaccine.


The Pfizer COVID-19 booster vaccine has been approved to allow for a single booster dose to be administered at least six months after completion of the original Pfizer vaccine series (e.g., at least six months after the second Pfizer vaccination). Considering this approval, we have compiled six things you should know about Pfizer’s COVID-19 booster.

1.   What is the difference between additional doses and booster shots?

A third, or additional dose, of the Pfizer or Moderna COVID-19 vaccine was previously approved by the FDA and CDC as part of the initial two-dose vaccine series for severely immunocompromised people. This was due to evidence showing that some immunocompromised people did not mount a good enough immune response with the initial two doses alone, so a third dose may help. People age 12 and older, whose immune systems are compromised moderately to severely, are currently eligible to receive a third dose of mRNA COVID-19 vaccine after the initial two doses.

“Booster shots” are typically for anyone who is eligible to receive a vaccine. These are beneficial to keep up immunities, as over the course of time, there are trends showing that after many months, the neutralizing antibodies that the vaccine helped create may start declining. Booster dose vaccinations for COVID-19 and other vaccine types can help because they are meant to remind the body’s immune system to keep those antibodies up.

If immunocompromised people have already received an additional COVID-19 vaccine dose, they would not need to get a booster shot at this time.

2.   Are vaccines effective in protecting against COVID-19 variants such as the delta variant?

According to the CDC, COVID-19 vaccinations are effective in protecting against severe disease and death from COVID-19 and its variants, including the delta variant.

Infections both variant and not occur in only a small fraction of fully vaccinated people. Infections that do occur in fully vaccinated individuals tend to be mild.

3.   Who is eligible to receive the Pfizer COVID-19 booster shot?

This booster vaccine is available only to those who have completed the original Pfizer two-dose series. In addition to this, in order to be eligible for the booster shot, at least six months must have passed since the second dose of the Pfizer COVID-19 vaccine.

Other requirements for eligibility include the following:

  • People who are 65 years and older.
  • People who are 18 years and older living in long-term care settings.
  • People who are 18 years and older with underlying medical conditions.
  • People who are 18 years and older working in a high-risk environment.
  • People who are 18 years and older living in a high-risk environment.

For more details, view the CDC’s guidelines.

4.   Where can you go for an  appointment for the Pfizer COVID-19 booster shot?

Individuals who are eligible for the Pfizer COVID-19 booster shot can make an appointment at any pharmacy that is offering it, including UC Health’s vaccine clinics, starting this Monday, Sept. 27.

Booster doses are available at the following UC Health locations by appointment only:

  • Clifton: UC Health Outpatient Pharmacy at Hoxworth Center: 3130 Highland Ave., Cincinnati, OH 45219.
  • Clifton: West Medical Office Building: 3120 Burnet Ave., Cincinnati, OH 45229. First floor, classroom E, corridor 1-01 (next to Suite 105).
  • Clifton: UC Gardner Neuroscience Institute parking garage drive-thru clinic: 3113 Bellevue Ave., Cincinnati, OH 45219. Weekends only.

5.   How do I schedule an appointment for the Pfizer COVID-19 booster shot?

Appointments are required to receive the Pfizer COVID-19 booster vaccine. You can schedule an appointment at UC Health in a few ways:

  • My UC Health (MyChart): You may schedule your vaccination appointment by logging onto your My UC Health account and selecting the option to schedule an appointment under the “visits” section (use MyChart app or com/myuchealth). This is the easiest and fastest way to schedule your appointment. Please call 513-585-5353 for further assistance with My UC Health.
  • You can also schedule your appointment by calling 513-584-DOSE (3673).

6.   What are the side effects of the Pfizer COVID-19 booster?

According to a recent study conducted by the CDC, of 12,591 individuals who received a booster shot and filled out surveys via a voluntary safety monitoring system, third-dose side effects were typically “well-tolerated.”

This means that side effects were consistent with those seen after the second dose and were mostly mild or moderate lasting over a short period of time.

The most common side effects noted were reactions such as pain or swelling of the injection site, fever and headache