Years In The Making

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One of the most common complaints heard from those who are COVID-19 vaccine hesitant is that the vaccines were created in less than a year, so how could they be safe? Well, making vaccines has often been described as a thankless task. To quote Dr. Bill Foege, one of the world’s greatest public health physicians, “Nobody ever thanks you for saving them from the disease they didn’t know they were going to get.” However, public health physicians consider vaccines to be an excellent return on investment because they prevent death and disability, especially when given in childhood.

So why do we not have vaccines for more vaccine-preventable diseases? The reason is that vaccines must show both high efficacy and phenomenal safety to warrant their use in healthy people, making product development a long and difficult process. Before 2020, the average time from conception of a vaccine to licensure was 10 to 15 years; the shortest was four years (for the mumps vaccine). The development of a vaccine for COVID-19 in 11 months was therefore an extraordinary feat. It was made possible by years of basic research on a novel vaccine platform, namely messenger RNA, or mRNA.

The principles behind nucleic acid vaccines, including mRNA vaccines, are rooted in Watson and Crick’s central dogma – that DNA is transcribed into mRNA, which in turn directs cells to make specific proteins. For over 30 years it has been known that the introduction of either DNA or mRNA into a cell or living organism results in the creation of a protein defined by the nucleic acid sequence in that DNA or mRNA. Soon thereafter, the concept of nucleic acid vaccines was validated when proteins created by cells exposed to outside DNA were shown to induce a protective immune response. Subsequent research showed that using mRNA was more practical than DNA for creating this immune response.

Years before COVID-19, based on this research, two biotech companies, Moderna and BioNTech, were licensed to create mRNA vaccines. These companies had to overcome a number of hurdles in developing vaccines including finding a way to keep the mRNA stable before introducing it to living cells. In 2017, testing led to the development of an mRNA vaccine that, when encapsulated and delivered by a lipid nanoparticle, boosted immunogenicity while maintaining a manageable safety profile. Both of the current licensed mRNA COVID-19 vaccines (Pfizer and Moderna) use lipid nanoparticle formulations.

We were fortunate that these advances in basic research had been completed before the pandemic and that the companies were therefore poised for success. The mRNA vaccines are safe, efficacious, and scalable; more than one billion doses have been administered, and the ability to scale further to supply two billion to four billion doses in 2021 and 2022 will be vital to the global fight against COVID-19. More generally, mRNA heralds a new dawn for the field of vaccinology and offers opportunities for protection against other infectious diseases, including malaria, HIV, and tuberculosis, which have been refractory to standard vaccine development attempts. Even cancers and genetic diseases may be vulnerable to this technology, which includes both mRNA vaccines and gene editing. The world owes a debt of gratitude to the dedicated scientists and researchers who have made these processes and vaccines possible.

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 By Peter Galvin, MD

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