Sorry for not posting last week; it was a pretty big week for public health! The first doses of COVID-19 vaccine were administered in the United States, and the U.S. Food and Drug Administration (FDA) authorized a second COVID-19 vaccine for use in the U.S. There are now two COVID-19 vaccines available in the U.S. If you’re one of the lucky few eligible to get COVID-19 vaccine during Phase 1a – or when it’s time for your priority group – which COVID-19 vaccine should you get? Read on for my thoughts.
The answer’s quite simple: get whatever COVID-19 vaccine your doctor, or employer, or clinic, or pharmacy has in stock. I don’t recommend “shopping around” and I certainly don’t recommend waiting for a preferred brand to come in stock near you. The Pfizer and Moderna COVID-19 vaccines are so similar to each other that they might as well be equivalent. With one exception, the only meaningful differences will only matter to whoever is responsible for storing and drawing up vaccines at your clinic, pharmacy or doctor’s office.
- Vaccine type: Both Pfizer’s and Moderna’s vaccines are mRNA vaccines. They’re made using similar technology and have extremely similar risks and benefits.
- Ingredients: Both vaccines’ ingredient lists are very similar, with only a few salts and sugars and one proprietary ingredient different between them. What does this mean to you? Check the ingredient lists. If you have an allergy to one of the few ingredients that’s different between the vaccines, then pick the vaccine that doesn’t have that ingredient. If you’re not allergic to an ingredient that’s in both vaccines, talk to your doctor but you probably shouldn’t get it. If you’re not allergic to any ingredients, then you can get either vaccine.
- Recommended age groups: This is the biggest difference, although it only impacts a relatively small number of people. Pfizer’s vaccine is authorized for people age 16 years and older; Moderna’s is for age 18 years and older. What does this mean to you? If you’re 16 or 17 years older and in a priority group for COVID-19 vaccine, ask your healthcare provider for Pfizer’s vaccine. If you’re 18 or older, then you can get either one.
- People who can’t get the vaccines: Both mRNA vaccines have the same contraindications (lists of people who cannot get the vaccine) and warnings. What does this mean to you? No difference. If you can’t get one of the COVID-19 vaccines, then you can’t get the other either.
- Effectiveness: The FDA found that Pfizer’s vaccine was 95% effective, and Moderna’s was 94.1% effective. I will tell you right now that less than 1 percentage point difference is similar enough to consider them equally effective, however if you’re like me, you want to see the data. Unfortunately, we don’t have head-to-head comparative studies of the two vaccines. However, we do have 95% confidence intervals for both effectiveness estimates. A confidence interval is essentially a margin of error around an estimate; specifically, a 95% confidence interval is the range of values within which we can be 95% confident the true value lies. I’m getting a bit wonky here, so let’s skip the stat talk and go straight to the numbers: Pfizer’s 95% confidence interval was 90.3% to 97.6%; Moderna’s was 89.3% to 96.8%. Those ranges are nearly identical, but most critically, both vaccines’ estimated effectiveness is within the same range of each other. They are equally effective and if one of them is slightly more effective than another, it is to such a small extent that it is statistically meaningless. What does this mean to you? Get either vaccine. They’re both essentially equally effective.
- Side effects: Both vaccines cause pain at the injection site, tiredness, headache, muscle pain, chills, joint pain, and fever. Of note, more people experienced these side effects after the second dose than after the first dose. Moderna’s clinical study found cases of swollen lymph nodes in the same arm as the injection, nausea and vomiting after vaccination, but Pfizer’s did not. What does that mean to you? Probably not much. As more people are vaccinated, we may find that Pfizer’s vaccine causes swollen lymph nodes and/or nausea and vomiting at similar rates to Moderna’s. However, if you have had issues with swollen lymph nodes or can’t tolerate nausea and vomiting then talk to your healthcare provider.
- Storage and handling, minimum purchase orders, doses per vial and dilution: Pfizer’s and Moderna’s vaccines have different temperature storage requirements, ship in different quantities, have different numbers of doses per vial, and Pfizer’s vaccine needs to be diluted before administration but Moderna’s does not. What does that mean to you? Unless you are responsible for ordering, storing and/or drawing up COVID-19 vaccine, not much, however your healthcare provider’s choice of vaccine may be influenced by these factors.
I don’t think I’m exaggerating when I say this is an historic moment. According to the CDC, over half a million doses of COVID-19 vaccine were administered in its first week in the U.S. Now that there’s a second vaccine coming out, we have the potential to triple or quadruple that number in the next week. When it comes time for your shot, unless you are 16 or 17 years old or have an allergy to one of the ingredients that is unique to one of the vaccines, take whichever COVID-19 vaccine your healthcare provider, clinic or pharmacy has in stock. I know I will.
Keep wearing your masks, have socially distant holidays, get your COVID-19 vaccine when you can, and let’s end this pandemic together.
🎁 Dr. B