Administration of a fourth type of Covid-19 vaccine has halted after a potential link between the substance and blood clotting of the brain has resulted in further product research.

Use on humans of the AstraZeneca Covid-19 vaccine has been temporarily halted while further research is being conducted on the possible correlation between the vaccine and numerous cases of a rare type of blood clot forming in the brains of some who have recieved this particular brand of shot, according to information shared by Reuters.

To date, there are currently three types of medically-cleared Covid-19 vaccines being given to Americans in an attempt to immunize against the virus that has been linked to over a half-million fatalities in the United States. The three types of vaccines in use are the Johnson & Johnson / Janssen, Pfizer-BioNTech and Moderna brands. Of the three types, the Johnson & Johnson / Janssen brand is the only songle-shot vaccine; both Moderna and Pfizer-BioNTech require two shots to achieve effectivness.

Well over 30 million cases of Coronavirus have been reported in the U.S., according to the Centers for Disease Control and Prevention. To date, nearly 170 million doses of the various vaccines have been administered. It is estimated that approximately 19% of the U.S. population has been fully vaccinated from Covid-19.

The CDC is still recommending social-distancing, frequent hand washing, mask wearing and avoiding large groups of individuals to help curb the spread of the virus.

LOOK: Answers to 30 common COVID-19 vaccine questions

While much is still unknown about the coronavirus and the future, what is known is that the currently available vaccines have gone through all three trial phases and are safe and effective. It will be necessary for as many Americans as possible to be vaccinated in order to finally return to some level of pre-pandemic normalcy, and hopefully these 30 answers provided here will help readers get vaccinated as soon they are able.

How can I stay safe while grocery shopping? And answers to 24 other coronavirus questions

Get our free mobile app