Curious about the AstraZeneca COVID-19 vaccine?

ALBANY, N.Y. (NEWS10)- Three COVID-19 vaccines have been approved for emergency use by the U.S. Food and Drug Administration (FDA). Pfizer's vaccine was the first to be approved, followed by Moderna and Johnson & Johnson.

AstraZeneca's COVID-19 vaccine is currently being used in the United Kingdom but it hasn't been without controversy. The vaccine was put on hold after reports of people experiencing blood clots upon receiving the vaccine, according to AstraZeneca's corporate website.

Use of AstraZeneca's vaccine was resumed after the Medicines and Healthcare Products Regulatory Agency and European Medicines Agency announced the benefits of the vaccine outweighed its risks, the pharmaceutical company said in a press release on March 18.

AstraZeneca COVID-19 vaccine Q&A

• Is AstraZeneca's vaccine like the Pfizer and Moderna vaccine or Johnson & Johnson's?

Similar to Pfizer and Moderna COVID vaccine, the AstraZeneca version is administered in two doses, according to the company. Unlike the Pfizer and Moderna versions, AstraZeneca's COVID-19 vaccine is not manufactured using Messenger RNA (mRNA). It uses an adenovirus to deliver genetic material into the cells, similar to Johnson & Johnson's version.

• What are the most common side effects?

According to a January report on the European Medicines Agency website, the top five most common side effects of AstraZeneca's COVID vaccine were:

• injection site tenderness (63.7%)
• injection site pain (54.2%)
• headache (52.6%)
• fatigue (53.1%)
• myalgia or muscle pain (44.0%)

• What is the efficacy rate?

AstraZeneca said its COVID vaccine has an efficacy rate of greater than 70% after the first dose, based on a clinical trial in the United Kingdom.

• Why hasn't it been approved for use in the U.S.?

Information and analysis of AstraZeneca's clinical trials in the U.S. will be submitted to the FDA in coming weeks, the company said on March 22. It will then be up to the FDA to approve its emergency use.