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Understanding the Covid-19 Vaccines

Updated: Dec 7, 2023

By Isabel Pulgarin

In January, a new strain of the Omicron variant called BA.2 was being tracked in the U.S. Despite the concern, the Centers for Disease Control and Prevention (CDC) maintained that vaccines continue to protect against severe symptoms, hospitalization, and death caused by the new strain. Thus, getting vaccinated remains important.

Photo Credit to Pexels

During the White House press briefing on Jan. 21 with President Biden’s COVID-19 Response Team, director of the CDC, Dr. Rochelle Walensky, and her chief medical advisor, Dr. Anthony Fauci, stressed the importance of vaccines and booster shots.

“Protection against infection and hospitalization with the Omicron variant is highest for those who are up to date with their vaccination, meaning those who are boosted when they are eligible,” said Walensky.

Booster shots “boost” your immunity and provide you with more protection against the virus, since it has been found that immunity from the first doses can waver after about five months.

Specifically against the omicron variant, after receiving both shots of the COVID-19 vaccine, effectiveness against hospitalization increased from 57 percent to 90 percent. In preventing emergency room and urgent care visits, effectiveness more than doubled from 38 percent to 82 percent.

Additionally, according to the CDC, when Omicron was surging this past December, the unvaccinated had a five times higher risk of infection compared to those who are fully vaccinated and received their booster.

In the U.S., a person is fully vaccinated two weeks after completing their two-dose series or one dose of the J&J vaccine. Being “boosted” means being fully vaccinated and having a single booster shot. All booster shots are effective immediately after administration.

Graphic Credit to Dyck Dorlean

On Barry’s own campus, about 86 percent of students who were surveyed by The Buccaneer said they are vaccinated, meaning they have two doses of either the Pfizer or Moderna or one dose of the J&J vaccine. Just 34 percent of students said they were boosted.

For students who are not vaccinated, choosing the right vaccine is important. Here is a guide with research compiled by Yale Medicine experts to answer any questions students may have about COVID-19 vaccines and their boosters.


The Pfizer vaccine is currently approved under Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) for children and adults ages five and older.

The first two doses must be taken 21 days apart. The CDC recommends three shots in total for people who are immunocompromised, including a booster shot.

A booster can be administered five months after the first two doses. People ages 12 and older can only get the Pfizer booster. Adults 18 and older can choose any of the three boosters available in the U.S.

As of April 2021, the Pfizer vaccine is 91.3 percent effective against COVID-19 infection. The CDC finds the Pfizer vaccine to be 100 percent effective in preventing severe disease, while the FDA considers it 95 percent effective.


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In January, the Moderna vaccine was granted full approval by the FDA. In late August, a third dose was approved for the immunocompromised. These doses are recommended for adults 18 and older.

Two doses of Moderna should be taken 28 days apart, with a half-dose Moderna booster or full-dose Pfizer-BioNTech booster five months after the last of the Moderna series. The Moderna booster can also be given after the first dose of J&J.

According to the FDA, Moderna and Pfizer vaccines have been known to cause heart inflammation, but in most cases, it decreases over time.

Johnson & Johnson/Janssen

Authorized in February 2021, the J&J vaccine is a single-dose vaccine.

In April 2021, after a two-week pause, the FDA attached a warning label to the J&J vaccine recommending caution after 54 cases of a “rare but serious” blood clotting disorder were reported, with 36 recipients having been in intensive care.

According to Yale Medicine, about three months later, the FDA attached another warning, citing about 100 recipients who developed a rare case of Guillain-Barré syndrome, a neurological disorder that causes muscle weakness and sometimes paralysis.

Photo Credit to Pexels

Still, the J&J vaccine is 86 percent effective against moderate and severe disease.

Because of the discrepancies with the J&J vaccine, the CDC now only endorses the Pfizer and Moderna vaccines, though the J&J is still available. The agency still maintains that the risks of COVID-19 outweigh the risks of the vaccine itself.

Students who wish to get vaccinated can get an appointment on campus. On May 5, first and second doses of the Pfizer vaccines will be available in the Landon Events Room. On May 24, only second doses will be available. Students can book appointments in their Student Health Portal under “Appointment Scheduling.”

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