A CLOSER LOOK: COVID-19 vaccines and what makes them different

A Closer Look

Los Angeles, CA – April 15: Liesl Eibschutz, a medical student from Dartmouth University, loads a syringe with Pfizer COVID-19 vaccine before giving it to people on the first day that people ages 16 and up can receive the vaccine at Kedren Health on Thursday, April 15, 2021 in Los Angeles, CA. (Allen J. Schaben / Los Angeles Times via Getty Images)

ARKANSAS (KNWA/KFTA) — When a person is vaccinated with any of the COVID-19 vaccines, it takes about two weeks for the body to build up protection against the virus, according to the Centers for Disease Control (CDC).

Four vaccines have been developed, but one is suspended as of Tuesday, April 13, as recommended by the CDC and the Food and Drug Administration (FDA), “out of an abundance of caution.”

LEIDEN, NETHERLANDS – APRIL 15: General exterior view of the head office of Janssen pharmaceutical company on April 15, 2021 in Leiden, Netherlands. The start of vaccinations in Europe with the coronavirus vaccine that was developed by Janssen Vaccines in Leiden, has been put on hold. A study is currently underway in the United States, where the Janssen vaccine has been used for some time, into reports of unusual blood clots, in combination with a reduced number of platelets. (Photo by Niels Wenstedt/BSR Agency/Getty Images)


The Johnson & Johnson (J&J/Janssen) single-shot vaccine is on ‘pause’ for at least a week, after six women developed blood clots in a combination with low platelets, one person has died, according to the CDC.

The J&J vaccine uses “adenovirus (a common virus that, when not inactivated, can cause colds, bronchitis, and other illnesses, per Yale Medicine).” This is from the double-stranded DNA viruses, identified in human adenoid tissue. Astra Zeneca also uses adenovirus but from chimpanzees. The J&J vaccine was approved for use in the U.S. on February 27, 2021.

A picture shows a closed vaccination center in the city of Nice, southern France, on April 18, 2021, amid the spread of the Covid-19 pandemic caused by the novel coronavirus. – The vaccination center, which was to remain open during the weekend to vaccinate the most at-risk people over 55, closed in the middle of the day on April 17, due to a lack of candidates for the proposed vaccination with the AstraZeneca/Oxford vaccine. (Photo by Valery HACHE / AFP) (Photo by VALERY HACHE/AFP via Getty Images)


In the U.K., 79 people who received their first dose of the Astra Zeneca (AZ) vaccine developed rare blood clots, of which 52 were women. Of the group 19 died, according to data from the UK’s  Medicines and Healthcare products Regulatory Agency (MHRA).

MHRA states that getting vaccinated is better than not getting vaccinated.

COVID-19 leads to a several-times higher risk of cerebral venous thrombosis (CVT) blood clots than current COVID-19 vaccines.

Oxford Research

The above information is from the University of Oxford researchers who released a report on Thursday, April 15.

As a disclosure, the Astra Zeneca (AZ/AZD1222) vaccine was co-invented by the University of Oxford and Vaccitech. The study, released Thursday, was led by Oxford University’s Professor Paul Harrison and Dr. Maxime Taquet. “They counted the number of CVT (cerebral venous thrombosis, also called cerebral venous sinus thrombosis CVST) cases diagnosed in the two weeks following diagnosis of COVID-19, or after the first dose of a vaccine. They then compared these to calculated incidences of CVT following influenza and the background level in the general population.”

They found that CVT is more common after a person has COVID-19 compared to other groups, and 30% of the cases were people under the age of 30.

CVT cases in COVID-19 patients compared to CVT cases in those who received a COVID-19 vaccine:

  • In this study of over 500,000 COVID-19 patients, CVT occurred in 39 in a million patients.
  • In over 480,000 people receiving a COVID-19 mRNA vaccine (Pfizer or Moderna), CVT occurred in 4 in a million.
  • After the first dose of the AZ-Oxford COVID-19 vaccine, CVT occurred in about 5 in a million people.
  • Compared to the mRNA vaccines, the risk of a CVT from COVID-19 is about 10 times greater.
  • Compared to the AZ-Oxford vaccine, the risk of a CVT from COVID-19 is about 8 times greater.

The researchers stated that data is still being collected. There may also be under-reporting or mis-coding of CVT in medical records, and therefore uncertainty as to the precision of the results.

This data should be interpreted cautiously, especially since the data on the Oxford-AstraZeneca vaccine come from UK MHRA monitoring, whereas the other data uses the TriNetX electronic health records network. However, the signals that COVID-19 is linked to CVT, as well as portal vein thrombosis – a clotting disorder of the liver – is clear, and one we should take note of.

Dr. Taquet.

AZ uses “a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body,” according to AZ’s website. J&J uses adenovirus but from humans, as stated above.


Both of the vaccines use messenger ribonucleuc acid (mRNA). These are single-stranded molecules that carry genetic code from DNA in a cell’s nucleus to ribosomes, which make protein in the cells. mRNA vaccines are a new type of vaccine to protect against infectious diseases, according to the CDC. The Pfizer-BioNTech was approved for use in the U.S. through an FDA EUA (emergency use authorization) on December 11, 2020. Moderna was approved, through an FDA EUA, on December 18, 2020. The vaccines require two shots.


  • Is it safe for me to get a COVID-19 vaccine if I would like to have a baby one day? Yes.
  • Will a COVID-19 vaccine alter my DNA? No.
  • Can CDC mandate that I get a COVID-19 vaccine? No.
  • After getting a COVID-19 vaccine, will I test positive for COVID-19 on a viral test? No.
  • Can a COVID-19 vaccine make me sick with COVID-19? No.

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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