by RM NAIR
NEW YORK, Nov 19: The vaccines developed by Pfizer-BioNTech and Moderna based
on mRNA technology have been found to be 95% effective against covid in Phase
3 trials. The efficacy of Pfizer's vaccine candidate, BNT162b2, was found consistent
across age, gender, race and ethnicity, and the observed efficacy in adults
over 65 years of age was over 94%, according to a statement issued by Pfizer.
It said that the vaccine was well tolerated across all populations with over
43,000 global participants enrolled and no serious safety concerns had been observed.
Likewise, Moderna had released its findings last week.
Pfizer will produce 50 million vaccine doses by this December and up to 1.3
billion doses by the end of 2021. The UK has pre-ordered 40 million doses, Europe
200 million doses and the US 100 million doses. Moderna is also contracted to
supply a large quantity to the US, which has financed the project heavily as
it has been an initiative of the NIH.
Pfizer plans to use its existing cold-chain infrastructure. The vaccine needs
to be stored at minus 70 deg C, the main drawback that has been cited as distribution
in rural and remote areas will be challenging operation. The company says they
have developed GPS-enabled thermal shippers using dry ice to maintain temperature
conditions of -70°. Although Moderna vaccine can be stored in refrigerator temperature
or minus 20 deg C.
Moderna and Pfizer plan to submit a request within days to the FDA for Emergency
Use Authorization (EUA).
“The study results mark an important step in this historic eight-month journey
to bring forward a vaccine capable of helping to end this devastating pandemic.
We continue to move at the speed of science to compile all the data collected
thus far and share with regulators around the world,” said Dr. Albert Bourla,
Pfizer Chairman and CEO.
Both Pfizer and Moderna vaccines are given in two doses in a space of a few
weeks.
What is mRNA technology
Their vaccines consist of a genetic code directing production of the coronavirus’
spike protein by the body's own cells. This spike protein makes immune system
to produce antibodies without the presence of virus as in the conventional vaccine.
The information is delivered in a fat bubble called lipid nanoparticle.
mRNA, a technology that has been in the works for several decades but never
found its first use, is being deployed in these two vaccines. In this technology,
human cells are instructed to produce its own vaccine by passing on a fabricated
genetic code of the virus spike protein.
The technology has high potential for the future, even could be leading to
groundbreaking developments in cancer research.
In the vaccine, a genetic coding for SARS-CoV-2 spike (S) protein is designed
and the code is inserted into a messenger RNA molecule to be injected. The human
cell produces the S-protein and displays the info on the cell surface, for the
immune system to respond and produce antibodies. Thereafter the memory of the
infection is stored which signals production of antibodies whenever the actual
viral infection takes place.
The mRNA technology eliminates the traditional use of attenuated or inactivated
virus or molecules or its fragments in the development of vaccines.
What happens when infection takes place? The virus enters the human cell. In
the case of coronavirus, it uses its spikes to cling on to the cell membrane
and that part is fused for the virus to enter the cell and using the cytoplasm
and vitals it replicates, rendering the cell a mere shell. In covid, immune
system responds very late such that it reacts very violently in order to eliminate
the infection which has by now spread too deep. In the overdrive, various organs
like kidneys, heart and brain are damaged by the very immune system, leading
to death. This upheaval is called cytokine storm. In most cases death is not
caused by the virus.
In conventional vaccines, the attenuated or inactivated virus signals the immune
system to respond and antibodies are created and the memory stored in the helper
cells for action when the actual infection occurs.
In the case of mRNA, no virus is injected but the body cells are made to produce
harmless viral proteins which in turn signals on cell surface the presence
of foreign object. The mRNA carries the genetic information code that makes
the cell produce the viral protein. The new vaccine is a modified spike protein
mRNA carried in a fat bubble.
The antibodies, helper cells and the T-cells all respond to the spike protein
produced in response to the instructions the new vaccine delivers.
The new vaccine eliminates the risks of infection that the conventional vaccines
might pose. And it continues to produce spike proteins for a couple of weeks.
Pfizer and BioNTech are using the technology developed by Pennsylvania university,
while Moderna has drawn its knowhow basically from NIH, which is officially
assisting the pharma.
The mRNA technology came to fruition just last week when both Pfizer and Moderna
announced the efficacy of the vaccines in final clinical trials as far above
90%. Both use synthetic messenger RNA. It does not contain any part of the virus,
so the recipients will not get the infection from the injection.
Dr Drew Weissman, a professor of medicine at the University of Pennsylvania
School of Medicine, has been working on mRNA for several decades now. He is
the guide for BioNTech, the German biotechnology company, working with Pfizer.
Covaxin, Cadila, Novavax, AstraZeneca, Johnson & Johnson, Sinovax and Sputnik
V are some of the conventional vaccines in the advanced stage.
With Phase 3 trial data, Pfizer and Moderna vaccines are ready
to apply for Emergency Use Authorization (EUA). Both will start
distributing the vaccines next month. Both have been found safe
and effective across a wide spectrum of volunteers. In Moderna,
instances of verified reactogenicity occurred in a few instances
but that should not necessarily feed vaccine hesitancy. It could
as well be an immune response to the lipid nanoparticle, the vehicle, and
not the vaccine molecule. Usual side-effects of these vaccines
included fatigue, muscle pain, joint pain, fever and headache.
But that is a small price.
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