Most people think of vaccines this way: you get vaccinated, and your immune system prepares to fight a virus or bacteria that enters the body. The vaccine serves as the catalyst to set up protection, prevent infection, and prevent you from infecting others.
Unfortunately, it is not quite that simple. Not all vaccines work that way, and it’s not actually what the two COVID-19 vaccines authorized by the U.S. Food and Drug Administration—made by Moderna and Pfizer-BioNtech—are designed to do. Their effectiveness is measured by how well they protect people against moderate to severe COVID-19 disease—not how well they prevent infection or spread of the COVID-19 virus itself.
Interestingly, although the shots are 94% to 95% effective in preventing disease, there is no definitive data yet that proves they completely shut down the virus enough to stop it from moving from an infected person to someone else. i.e. if that vaccinated but the infected person isn’t wearing a mask or isn’t keeping the recommended six feet apart from others.
This lack of data explains why public health officials have said that even if you’re vaccinated, you need to continue wearing the mask, remaining six feet apart, and avoid large gatherings – even if your guests are all vaccinated, start holding intimate dinner parties with your other vaccinated friends and family.
Several months will need to pass in order to see if the virus moves from a vaccinated person to someone else.
AstraZeneca and one by a group of Israeli scientists recently published data suggesting that COVID-19 vaccines might reduce the spread of the virus.
On Feb. 1, AstraZeneca and its academic partners at the University of Oxford reported the results of their late-stage, Phase 3 studies of their vaccine. It’s made from a weakened adenovirus that causes infections in chimps, which was modified to carry the genetic instructions for making a COVID-19 viral protein.
This protein triggers the human immune system to make antibodies against it, which, if the vaccinated person is then infected with the virus, can block the actual COVID-19 virus from sticking to and infecting cells.