Weekly newsletter:
November 16-22 2020
Level difficulty:
The Pfizer COVID-19 vaccine: the beginning of the end of the pandemic?
The American company Pfizer, in collaboration with BioNTech, has just announced the development of a vaccine that has a 90% success rate against SARS-CoV-2, the virus that causes COVID-19. Although this new announcement has been received very positively for the most part, it nevertheless raises certain questions. Its effectiveness seems undeniable, but we still don’t know the length of the immunity it provides and whether it can prevent serious cases: clinical tests have been carried out only on patients with moderate symptoms for the moment. Its effect on older patients is also still to be confirmed.
But the most serious issue concerns distribution. The vaccine functions through using a tiny piece of the DNA of SARS-CoV-2, necessary for the expression of a protein in the viral envelope. It’s very rare to create a vaccine from the DNA of the virus. This piece of DNA is used by the dendritic cells for presentation to T cells, stimulating the production of anti-SARS-CoV-2 antibodies and generating immune memory.
This can be shown diagrammatically thus:
However, the DNA needs to be conserved at -80°C, which complicates worldwide distribution enormously.
The vaccine, still at the clinical trials phase and involving 44 000 volunteers and 154 testing sites across the US, may qualify for “Emergency Use Authorization”, granted by drug safety authorities in the country. This EUA can only be put in place 2 months after half of the trial’s participants have received their last dose of the vaccine.
For the moment the United States has ordered 100 million doses of the vaccine and the EU 300 million. However, even if in a best-case scenario the vaccine began to be commercialised before the end of the year, restrictive sanitary measures would continue during the vaccination period. It’s clear that social distancing will not be ending in the immediate future.
