Super-infection cases, in which a huge number of individuals are contaminated, are already a typical occurrence of the COVID-19 pandemic.
The latest Covid-19 vaccines from Pfizer and Moderna tend to be exceptionally effective at avoiding severe illness.
More than 100,000 Americans are in COVID-19 hospital, while the nation has recorded its one-worst daily death toll since the pandemic began.
The CDC has updated its guidelines on the spread of COVID-19.
Public health authorities and drug manufacturers need to be open regarding the side effects of coronavirus vaccines, doctors say.
Both the Pfizer vaccine and the Moderna vaccine were developed with new technology that uses messenger RNA.
Coronavirus Covid-19 increased by 467 percent in Kansas counties, requiring masks in public places.