No doubt you’ve seen the pictures or heard the news: COVID-19 vaccines are here. Sandra Lindsay, a critical care nurse at the Long Island Jewish Medical Center in Queens, NY, became the first person in the U.S. to receive a COVID-19 vaccine outside of a clinical trial. After the FDA approved the Pfizer-BioNTech vaccine for emergency use on Dec. 11, Lindsay got inoculated on live TV on Dec. 14.
While this is incredible news, the vaccines aren’t widely available yet—and we don’t know when they will be. An emergency use authorization (EUA) isn’t the same thing as full-on FDA approval. That means the vaccine is currently only available to limited groups, like healthcare workers and nursing home residents.
Experts are extremely hopeful that continued testing will go smoothly, and say that so far, there’s not much to worry about in terms of effectiveness. “We have a vaccine that so far looks very effective, and so far, looks quite safe,” says Dr. Martin Hirsch, M.D., Professor of Medicine at the Harvard Medical School and Professor of Infectious Diseases and Immunology at the Harvard School of Public Health. “We can’t make promises that something won’t happen at some point. But the best we can do is say that the risk benefit ratio today strongly favors use of the vaccine. I’m certainly looking forward to getting my vaccine.”
Many vaccines are “live” vaccines (think: the MMR shot or the flu shot). These contain live, weakened versions of a disease, that the body recognizes and builds up an immune defense against. But, twist! The COVID-19 vaccines that are in play right now do notcontain the live virus. Instead, they work using mRNA technology.
When you see pictures of COVID-19 cells, you can spot those telltale “spikes” surrounding the cell. “These famous spikes are used by the virus to enter our cells, mostly in those in our airways—nose, throat and lungs,” says Dr. Noam Tau, a physician and researcher at Israel’s Sheba Medical Center who studies vaccine safety. “These spikes are also the ‘face’ of the virus, which our body recognizes when it creates an immune response.”
So, how does an mRNA COVID vaccine work? Essentially, Dr. Tau says, you can think of it like an “instruction booklet” on how to build those COVID-like spikes. “The body then takes the instruction book and inserts it into our cells which create a whole lot of spikes,” he explains. “These spikes, of course, are not capable of causing any disease, and only help teach our immune system how to protect itself against COVID-19. The spike instruction book is then destroyed, and none of it should be left in our cells within a short period of time after the vaccine.
The two mRNA vaccines closest to public release come from Pfizer-BioNTech (that’s the one that received the EUA on Dec. 11) and Moderna, which received the EUA on Dec. 15. There are a bunch of similarities between the two: They are both injected into muscles, their large-scale clinical trials have shown that they are over 94% effective, and they both require two doses to be given over the course of three or four weeks…