Pfizer and Moderna:
"...mRNA vaccines carry strands of mRNA that, in the body, function like an instruction manual. For COVID-19 vaccines, those instructions tell the body how to create a piece of the “spike protein” unique to SARS-CoV-2, the virus that causes COVID-19.
Because the mRNA encodes only for the spike protein — by itself a harmless protein found on the surface of the actual virus —
the vaccine cannot cause COVID-19 infection. It is antigenic, though, meaning it can provoke an immune response in the body that helps create the antibodies necessary to fight COVID-19 effectively.
Once the spike protein is created in the body using the mRNA instructions, the body’s cells use enzymes to quickly break down the mRNA strands for removal by normal cellular processes. The mRNA doesn’t actually enter the nucleus of any cell (where your DNA is located) or affect genetic material in the body....."
The COVID-19 vaccine development process was accelerated and there is more to learn on how this vaccine works. Read on as an Ohio State expert shares information about mRNA vaccines.
wexnermedical.osu.edu
JnJ:
Viral vector vaccines use a modified, harmless version of a
different virus as a vector, or carrier, to deliver immunity instructions to cells in the body. The body then follows those instructions to build an immune response to the intended virus (in this case, SARS-CoV-2, which causes COVID-19.)
The virus vector being used in the Johnson & Johnson and AstraZeneca vaccines is an
adenovirus, a common type of virus that typically causes mild cold symptoms when it infects someone.
COVID-19 viral vector vaccines inject a harmless adenovirus vector, which carries unique genetic information from the COVID-19 virus to human cells. Once it reaches human cells, the vector uses that genetic information with the cell’s machinery
to produce a COVID-19 spike protein (a small piece of SARS-CoV-2) on the cell’s surface. That spike protein triggers a response from the body’s immune system to start producing antibodies to COVID-19.
The antibodies created are specific to the virus that causes COVID-19, meaning the body is then prepared to protect against any future infections of the SARS-CoV-2 virus.
Pros and cons of viral vector vaccine technology
Viral vector vaccines work well in pandemics because they’re easy to produce quickly and in large volumes. Decades of clinical data show that adenoviruses in particular can trigger a strong immune response in humans, making them especially effective.
However,
if a viral vector vaccine uses a virus that you’ve already been exposed to and, therefore, have pre-existing immunity for, the vaccine won’t be as effective for you. That’s why scientists creating these vaccines try to choose versions of viruses that we’re unlikely to encounter naturally — in the Johnson & Johnson and AstraZeneca vaccines, the adenovirus is a strain that is found only in chimpanzees..."
COVID-19 vaccine candidates from Johnson & Johnson and Oxford/AstraZeneca use a viral vector vaccine technology that's been studied since the 1970s.
wexnermedical.osu.edu
Attenuated vaxes:
An attenuated vaccine (or a live attenuated vaccine) is a vaccine created by reducing the virulence of a pathogen, but still keeping it viable (or "live").[1] Attenuation takes an infectious agent and alters it so that it becomes harmless or less virulent.[2] These vaccines contrast to those produced by "killing" the virus (inactivated vaccine).
Attenuated vaccines stimulate a strong and effective immune response that is long-lasting.[3] In comparison to inactivated vaccines, attenuated vaccines produce a stronger and more durable immune response with a quick immunity onset.[4][5][6] Attenuated vaccines function by encouraging the body to create antibodies and memory immune cells in response to the specific pathogen which the vaccine protects against.[7] Common examples of live attenuated vaccines are measles, mumps, rubella, yellow fever, and some influenza vaccines.[3]
en.wikipedia.org
