We Have Two COVID Vaccines
Late Thursday night, the FDA announced it would issue an Emergency Use Authorization (EUA) for the COVID Moderna vaccine, bringing our immunization arsenal to a total of two. This vaccine is similar to the Pfizer / BioNTech vaccine that received EUA certification last week.
This is great news that we now have two vaccines, although they are similar, because that means two companies can now produce and distribute doses for the vaccine. The supply is still limited, so so far only a handful of people have been able to get the vaccine – mostly doctors and other healthcare professionals .
So are two vaccines approved?
Not Approved: “Permitted for emergency use.” Basically, this is a temporary permit for use during a pandemic. The FDA expects both companies to continue research and apply for full approval when they can.
The difference is important because the EUA can be quickly withdrawn if new information emerges that suggests that it is not safe enough or effective enough. This also only applies to emergencies, so if COVID vaccines are to become part of our new norm, they will eventually have to go through the same paperwork as for any other vaccine.
Also, as I write this, the second EUA has not actually been provided. When the Pfizer vaccine was reviewed last week, an FDA advisory group met on Thursday and the FDA prepared white papers by Friday night. They don’t seem to be in too much of a rush this time around, so it could go official over the weekend rather than today.
Are the two vaccines basically the same?
Quite a bit of. They both contain mRNA that encodes the coronavirus spike protein. This mRNA is coated with a lipid nanoparticle, like a tiny soap bubble, and then thousands of these particles are suspended in a solution of sugars, salts and / or pH-stabilizing buffers. That’s all.
Once injected, our cells use the mRNA to create a spike protein , and then our immune system reacts to the spike protein, giving us immunity. This immune response can cause us pain in our arm and sometimes fever, chills, or fatigue for a day or two.
Both vaccines have been shown to be about 95% effective in trials. Both vaccines are given in a series of two doses, but the cumulative incidence charts shown above show that protection begins about 14 days after the first dose. Thereafter, people in the control groups continued to contract COVID (ascending line), while very few cases were detected in the vaccine groups (straight line).
What are the differences?
Two doses of Pfizer / BioNTech vaccine are given three weeks apart; doses of Moderna vaccine are given four weeks apart.
The side effects of both are similar, with the possible side effects from the Moderna vaccine stronger. Temporary armpit lymph node enlargement was more common with this vaccine than with Pfizer. However, the side effects of both drugs are mild to moderate for most people.
The Pfizer / BioNTech vaccine is approved for use in people aged 16 and over; Moderna vaccine is for people 18 years of age or older.
The storage is also different. Moderna vaccine can be stored in a normal freezer temperature. The Pfizer / BioNTech vaccine has to stay very cold, so it is distributed in thermos flasks, each containing 975 doses. The packaging keeps the vaccine cold enough, but the large number of doses means there is no easy way to get the vaccine to small clinics. In the future, it is possible that rural and remote areas are more likely to use Moderna vaccine.
Can I mix and match?
Both vaccines require two doses, but there have been no trials to check what happens if you receive one dose of each. Therefore, your second dose should be the same vaccine as the first.
Manufacturers plan to give people a wallet card to remind them which vaccine they received and when to return for a second dose. Keep it to yourself or take a picture with your phone.
Each vaccine has a separate code for medical records, so if you forget which vaccine you got, you should be able to ask your doctor (or the clinic where you got the vaccine) to find out. These separate codes also mean it will be easier to determine if there are side effects or other problems that correlate with one vaccine versus another when looking at medical records.