As cases of Covid-19 continue to rise across the United States, countries around the world are preparing to begin administering future vaccines to fight the novel coronavirus. The two vaccine candidates most likely to receive FDA approval in the United States are made by Boston-based Moderna and New York-based Pfizer.
While early evidence showing Moderna’s vaccine to be very effective is promising news, multiple obstacles could interfere with its safe and effective administration. Here’s what you need to know.
The coronavirus is studded with proteins, so-called “spike proteins,” that it uses to enter and infect cells. The Moderna vaccine uses messenger RNA - mRNA for short - to instruct human cells to build spike proteins. These spike proteins migrate to the surface of our cells, where they are recognized by the immune system.
The immune system will react by creating antibodies that will target the spike protein. These antibodies are able to latch onto the spike proteins on the outside of the coronavirus, tagging it for destruction and preventing it from infecting other, healthy, cells.
mRNA is actually very fragile, and would be chopped to pieces by our natural enzymes if it were injected directly into the body. To prevent this from happening, Moderna’s mRNA vaccine is wrapped inside a lipid bubble.
Because mRNA molecules will also fall apart at room temperature it will need to be refrigerated while shipped at freezing temperatures, -20 degrees Celsius (-4 degrees Fahrenheit). It can then be stored at the temperature for six months without falling apart, which makes it the choice vaccine for rural areas that don’t have specialized freezers.
In a trial of 30,000 people across the United States, scientists randomly assigned volunteers to receive either the Moderna vaccine or a placebo. Over time, 196 of those volunteers got sick with Covid-19. But of those 196 cases, 185 occurred in the placebo group and only 11 in those who were vaccinated. Based on this data, Moderna concluded that its vaccine was found to be 94.1% effective, which is much higher than the FDA’s 50% effectiveness requirement.
In order to fully prepare the immune system to fight the coronavirus, Moderna’s vaccine requires two injections given 28 days apart. Though researchers are not yet sure how long the immunity created by the vaccine will last, an early study suggested it provides protection for at least three months
Moderna intends to manufacture approximately 20 million doses in 2020 and 500 million to one billion in 2021. On November 30, Moderna sought emergency authorization from the FDA to administer their vaccine to the public.
The Food and Drug Administration will likely grant emergency authorization for the vaccine this week, setting the stage for its distribution to millions of Americans across the country. According to government projections, Moderna will provide enough vaccines for 10 million people by the end of this year.