As each state in the U.S. is in charge of its own vaccine rollout, we’ve put together the table at the end of this article to help you get information on what’s happening in your state (see table below).
Comparison of FDA-Authorized Vaccines
Pfizer / BioNTech (mRNA) |
Moderna (mRNA) |
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Efficacy | After 1st dose: 52% (Some protection as early as 10 days after 1st dose).
After 2nd dose: 95% |
Also after 1st dose: Not known
And after 2nd dose: 94% (Efficacy in those 65 and older is a little lower, about 86%; however, overall, some evidence of greater protection against severe disease) |
Most Common Side Effects | Injection site pain, fatigue, headache, muscle pain, chills, joint pain, fever; more common after 2nd dose. Side effects noted to be lower in people 56 and older. | Injection site pain, fatigue, headache, muscle pain, joint pain, chills, nausea/vomiting, fever; more common after 2nd dose.
Side effects after 2nd dose more common with Moderna than Pfizer. Facial swelling in 2 people with a history of dermal (skin) fillers has also been reported 1-2 days after the last dose. |
Duration of side effects | Can last several days | Typically one day, but can last up to one week |
Serious allergic reaction | Low rate of severe allergic reactions (4.7 cases per million doses) but nearly double the rate for Moderna.
Treatable with epinephrine. Affected people should not receive 2nd dose. |
Low rate of severe allergic reactions (2.5 cases per million doses).
Treatable with epinephrine. Affected people should not receive 2nd dose. |
Where to Get | Requires very low-temperature storage, so availability may be more limited to hospitals and specialized settings. | Requires only regular refrigeration, so maybe more broadly available, such as in doctor’s offices, clinics, rural locations. |
Ingredients (per dose)
(Note: PEG is polyethylene glycol) |
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Based on adverse reports from several million vaccinations in the U.S. through mid-January, 2021 the safety profiles of the Pfizer and Moderna vaccines are consistent with the safety profiles observed during the pre-authorization clinical trials (CDC, COVID-19 Vaccine Safety Update 2021).
Be aware that some data with the Pfizer vaccine showed that it had no efficacy in the general population until day 14, with the incidence of new infections actually increasing until day 8 after first-dose vaccination, which the researchers hypothesized may have been caused by vaccinated people being less cautious reducing exposure risk, highlighting the importance of adherence to safety measures even after being vaccinated (Hunter, medRxiv 2021 — preprint).
The risk of new infections drops dramatically thereafter, with a 51.4% reduction in infections 13 to 24 days after the first dose relative to the first twelve days (Chodick, medRxiv 2021 — preprint). On a day-by-day basis, the estimated effectiveness of the first dose was shown to increase each day from day 14 until day 21 — at which time the actual incidence of infection was reduced by 91% compared to the first 12 days (Hunter, medRxiv 2021 — preprint). This is consistent with a report from the UK that re-analyzed cases of infection that occurred during the Pfizer pre-authorization trial on only days 15 through 21 after the first dose and found that the vaccine efficacy during this time interval was 89% compared to placebo.
While this evidence strongly suggests that just one dose of an mRNA may provide significant protection against COVID-19 within three weeks, it is uncertain how long immunoprotection persists. The second dose significantly boosts immune responses and is the basis for the vaccine’s efficacy in clinical studies. In the U.S. you are strongly recommended to get both doses of the mRNA vaccines.
Analysis of data from Israel among more than 1.7 million people who received both doses of the Pfizer vaccine estimated the vaccine’s effectiveness in preventing severe disease to be in the range of 87% to 96%. To prevent SARS-CoV-2 positive cases (that is, any level of disease), its effectiveness was in the range of 66% to 85%. This shows that a significant number of infections can still occur, although few will be severe. Vaccine effectiveness was somewhat greater among those younger than 60 than among older people (Aran, medRxiv — preprint).
The Advisory Committee on Immunization Practices (ACIP), a group of medical experts that develops recommendations for vaccine use in the U.S., has advised the Centers for Disease Control and Prevention (CDC) that the vaccines be provided in phases as shown in the table below, although states do not have to abide by these recommendations (Dooling, MMWR Morb Mortal Wkly Rep 2021).
The vaccine offered may depend on the setting, e.g., due to special refrigeration requirements (see comparison table), access to the Pfizer vaccine may be more limited to hospitals and specialized settings.
Information provided by ConsumerLab.com