What is a modRNA vaccine and is it safe?

Sarah Kiehl, an intensive care unit nurse who has been treating patients with the novel coronavirus at Truman Medical Center, receives a dose of Pfizer's COVID-19 vaccine on December 14, 2020, making her one of the first Missourians vaccinated against the virus. (Photo courtesy of Truman Medical Centers/University Health)

The first COVID-19 vaccine is now authorized for emergency distribution, yet only 58% of Americans are willing to take it. It’s like racing to build Apollo 11, but Neil Armstrong refused to get on board. Who doesn’t want to go to space?

This is where the scientist in me gets giddy, because with a little biology and research history, we can keep vaccine safety fears at bay. So call me Ms. Frizzle, and jump aboard the magic school bus, because we’re about to take a ride.

The Pfizer vaccine is actually incredibly simple, all things considered. It contains only 10 ingredients total: four types of fats (e.g. cholesterol) to help provide the vaccine structure and cell permeability, four types of salts (e.g. table salt) to maintain stable levels of pH, one sugar (i.e. sucrose) from your kitchen cabinet to protect the vaccine when it’s frozen, and the main ingredient, a nucleoside-modified messenger RNA, or modRNA for short.

That last one sounds much scarier than it is — kind of like when we call water by its chemical name, dihydrogen monoxide. In essence, it’s very similar to the mRNA already produced in your body.

If you recall, mRNA is the protein-making template that acts in a cell’s cytoplasm, not inside the nucleus, meaning it can’t alter your DNA. This gave scientists a tool for making an effective vaccine — without having to give you the virus itself — by leveraging the mRNA system combined with the genetic code for the SARS-CoV-2 protein spikes, which are relatively harmless on their own. In creating a modRNA template to make the spikes, the body can temporarily produce the proteins on its own to trigger an immune response, even without the whole virus attached.

Because your immune system still activates, typical symptoms such as fatigue and headaches can occur, but it allows you to build immunological defenses so that if you encounter the real virus, your body will spring into action.

This breakthrough has limitations. Practically speaking, mRNA is typically short-lived, which is why it has been slightly modified to last longer and needs to be packaged inside basic fats, salts and sugar to provide the most compatible and stable delivery in the body. It’s also why this vaccine requires colder temperature storage than others, to further preserve the modRNA. Combined, these allow just enough time for your immune system to respond before it breaks down. Of note, there are zero preservatives in this vaccine.

The coolest thing about this technology is that it was designed using decades of established science, the newest part being the specific genetic coding for the protein spikes. Messenger RNA was discovered in 1961, and mRNA vaccine technology dates back as early as the 1990s.

As it happens, there were major breakthroughs leading up to 2018 — well prior to COVID-19 — that made this technology viable when the pandemic hit. Combined with significant advances in genome sequencing, and research on past coronavirus strains, the speed of development is really a testament to the existing science and what we can achieve with enhanced funding — just like the race to the moon or the Manhattan Project.

For those concerned about political interference under President Trump, rest assured the United States government had absolutely nothing to do with the research and development of Pfizer’s novel vaccine. Regretfully, part of Trump’s mishandling of pandemic was his blatant refusal to invest sufficiently in diverse vaccine technologies.

Alas, the Pfizer vaccine was created in collaboration with BioNTech, a company based in Mainz, Germany, that was primarily funded by the German government under Chancellor Angela Merkel, a scientist herself. The United Kingdom has also approved the Pfizer vaccine, along with Dr. Anthony Fauci, and the overwhelming majority of the FDA’s independent advisory committee for vaccines, satisfying alternative safety criteria made necessary given the recent politicization of the FDA.

Still, it’s worth noting that standard drug safety protocols for FDA approval and emergency use remain wholly intact for COVID-19 vaccines. The speed in authorization comes largely from prioritized review and enhanced efficiencies in clinical trials, not by cutting corners on safety.

In fact, the only FDA requirement that was changed for COVID-19 vaccines was a lowering of minimum efficacy requirements, which ended up not being necessary as the Pfizer vaccine has demonstrated 90% efficacy with minimal side effects. This delightful surprise for a first generation vaccine is likely attributable to the new technology coupled with essentially dumb luck that the virus contained easily targetable protein spikes.

Wide acceptance of vaccines is critical to overcoming the pandemic. Vaccines work most effectively when herd immunity is reached, a process by which enough people become vaccinated that it is more difficult for the virus to spread. This contributes to fewer outbreaks, and therefore fewer cases, and often reduces the severity of symptoms in those who do become infected. For COVID-19, epidemiologists expect a threshold of roughly 70% of the population to be vaccinated to achieve protection, meaning 58% of Americans aren’t enough.

Accordingly, masks and physical distancing will be necessary until sufficient levels of protection are achieved. If you want the pandemic to end faster, adhere to basic hygiene recommendations and commit to getting the vaccine as soon as it is available to you.

For policymakers, enhancing educational-based public health campaigns for vaccine safety is paramount, as is bipartisan support, given Democrats still remain 20% more likely than Republicans and independents to take the vaccine. With benefits that easily appeal to both parties — including expedited economic recovery and protection for vulnerable populations — only together can we end this pandemic as quickly as possible.