No single COVID vaccine is clearly “the best” for everyone. The three vaccines available in the U.S. for the current season, Moderna, Pfizer-BioNTech, and Novavax, all provide similar protection against severe illness and hospitalization. The real differences come down to how they work, how they feel afterward, and which one fits your age, health status, and preferences.
How Well the Current Vaccines Work
The 2024-2025 updated vaccines reduced COVID-related emergency department and urgent care visits by about 33% among adults 18 and older during the first four months after vaccination. For adults 65 and older, protection against hospitalization was stronger, around 45-46% for people with healthy immune systems. Those numbers drop to roughly 40% for older adults with weakened immunity.
These figures are lower than the 90%-plus effectiveness numbers from the original vaccines in 2020-2021, but the virus has changed substantially since then. The current vaccines are reformulated to target newer variants, and their main value is keeping people out of the hospital rather than preventing every infection. Protection against any symptomatic illness tends to fall below 30% by about nine months after a booster dose, according to a large meta-analysis published in JAMA Network Open. Protection against severe outcomes holds up longer.
Moderna vs. Pfizer vs. Novavax
Moderna and Pfizer both use mRNA technology. Your cells read the mRNA instructions, build a piece of the virus’s spike protein, and your immune system learns to recognize it. Novavax takes a more traditional approach: it delivers a lab-made version of the spike protein directly, paired with an ingredient called an adjuvant that helps activate your immune response.
In terms of antibody production, mRNA vaccines generally come out ahead. A UK trial published in The Lancet found that vaccine schedules containing at least one mRNA dose produced the highest levels of neutralizing antibodies, with a Pfizer-then-Moderna combination generating the strongest antibody response of any pairing tested. Moderna’s slightly higher mRNA content likely explains why it edges out Pfizer in head-to-head antibody comparisons.
But antibodies aren’t the whole picture. The same trial found that Novavax, when combined with a different vaccine platform, was better at stimulating a type of immune cell response (interferon-gamma production) that may contribute to longer-lasting immune memory. So while mRNA vaccines are better at generating a quick, strong antibody surge, protein-based vaccines like Novavax may complement the immune response in a different way.
Side Effects Across the Three Vaccines
All three vaccines commonly cause injection site pain, fatigue, and sometimes fever. Novavax’s clinical data gives a useful baseline: among adults 18-64, about 81% reported pain at the injection site after the second dose, 58% had fatigue, and around 6% developed a fever. Older adults experienced milder reactions across the board, with 61% reporting injection site pain and only 2% getting a fever after dose two.
Moderna tends to produce slightly more noticeable side effects than Pfizer, likely because it delivers a higher dose of mRNA. Both mRNA vaccines carry a small risk of heart inflammation (myocarditis or pericarditis), which is most common in young men after the second dose. The risk is real but rare. For Novavax, one analysis estimated roughly 5.3 excess cases of myocarditis or pericarditis per 100,000 people vaccinated, weighed against about 1,805 COVID cases prevented per 100,000. mRNA vaccines carry a similar or slightly higher rate of this side effect. In all cases, vaccine-associated myocarditis is typically mild and resolves on its own, while COVID-caused myocarditis tends to be more serious.
If you had significant side effects from an mRNA vaccine previously, Novavax offers a different mechanism that some people tolerate better. It’s also an option for people who prefer a vaccine built on more traditional protein-based technology.
Who Should Get What
For most adults aged 12-64, all three vaccines are available and any of them is a reasonable choice. The CDC’s 2025-2026 guidance recommends one dose for anyone previously vaccinated, given at least eight weeks after the last dose. If you’ve never been vaccinated, one dose is still the standard starting point for this age group.
Children under 12 have fewer options. Kids aged 5-11 can receive either Moderna or Pfizer. Children aged 2-4 are limited to Moderna only. Infants and toddlers aged 6-23 months need two doses of Moderna if they’ve never been vaccinated, spaced four to eight weeks apart.
Adults 65 and older get a more robust schedule: two doses are recommended, with the second given about six months after the first. This age group can choose from Moderna, Pfizer, or Novavax. Given that hospitalization protection for seniors hovers around 45%, staying current with the recommended schedule matters more than which specific brand you pick.
If You’re Immunocompromised
People with weakened immune systems, whether from medication, organ transplants, cancer treatment, or conditions like advanced HIV, can receive additional vaccine doses beyond the standard schedule. After completing the initial series, you’re eligible for extra doses at least two months apart, in consultation with a healthcare provider. You don’t need documentation proving your immune status; self-confirmation is accepted.
The CDC data shows that vaccine effectiveness for immunocompromised adults 65 and older was about 40% against hospitalization, somewhat lower than the 45-46% seen in immunocompetent adults of the same age. This gap reinforces why extra doses can be valuable for this group. If you recently had COVID, waiting three months before your next vaccine dose is a reasonable approach, counting from when symptoms started or when you tested positive.
Does Mixing Vaccine Brands Help?
Yes, in some cases. The Lancet trial found that mixing brands can produce a stronger immune response than sticking with the same vaccine for every dose. The combination of Pfizer followed by Moderna generated the highest antibody levels of any schedule tested. Mixing an adenovirus-based vaccine (like the original AstraZeneca shot, no longer used in the U.S.) with Novavax produced the strongest cellular immune response.
You don’t need to seek out a specific brand switch, but if you received Pfizer previously and Moderna is what’s available at your pharmacy this time, that’s not a compromise. It may actually be a slight advantage.
The Bottom Line on Choosing
If you want the highest antibody response and don’t mind slightly more noticeable side effects, Moderna has a small edge. If you want a gentler experience or prefer not to receive an mRNA vaccine, Novavax is a solid alternative with comparable real-world protection. Pfizer falls in the middle on both counts. The differences between them are modest enough that the most important decision isn’t which vaccine you get, but whether you stay current with the recommended schedule for your age group.