If you’re asking whether COVID vaccines have side effects, yes, they do. A 2022 review on COVID-19 and vaccine-induced thrombosis names vaccine-induced immune thrombotic thrombocytopenia (VITT), a clotting condition, as a rare vaccine side effect. For the common reactions, how soon they start and how long they last, check the prescribing information for the vaccine you’re offered and talk with your clinician.
Do COVID vaccines have side effects?
Yes. A 2023 review of COVID-19 vaccine evolution covers the mRNA shots from Moderna and Pfizer-BioNTech, the viral vector shot from Janssen and the protein-based shot from Novavax, along with their side effects and their use as boosters.
Is there a serious side effect I should know about?
The 2022 review focuses on VITT and says that “several cases of vaccine-induced thrombosis have been reported.” Its statement on risk reads: “There is a broad consensus that the benefits of vaccination greatly outweigh the potential risks of rare vaccine side effects, such as vaccine-induced immune thrombotic thrombocytopenia (VITT).” The word that matters is rare. Each vaccine’s label lists its other side effects. Ask your clinician whether this applies to your own health history.
Which COVID vaccines are covered, and for what ages?
Medicare’s COVID-19 vaccine coverage page says that as of November 2026, Medicare Part B covers the updated 2025–2026 formula vaccines for anyone who has Medicare. It lists the age floor for each product:
| Vaccine (2025–2026 formula) | Age floor Medicare lists | Medicare coverage |
|---|---|---|
| Moderna Spikevax | 6 months or older | Part B covers |
| Moderna mNexspike | 12 years or older | Part B covers |
| Pfizer-BioNTech | 5 years or older | Part B covers |
| Novavax | 12 years or older | Part B covers |
Whether a particular shot fits you is a question for your clinician, not for this table.
Is there a deadline for the new COVID shot?
If a news headline about a COVID shot deadline brought you here, Medicare’s page doesn’t state a deadline; it points to CDC.gov for the current schedule. For the current season’s schedule, Medicare’s page points to CDC.gov. Because the Medicare page lists the 2025–2026 formula, ask your pharmacy or clinic which formula they are giving before you book.
When do side effects start, and how long do they last?
Check the prescribing information for the specific vaccine for when reactions usually appear and how long they usually last. If a symptom worries you, or you are unsure whether it is related to the vaccine, ask your clinician or pharmacist. Our flu season symptoms guide compares cold, COVID and RSV questions, and how long is the flu contagious covers the flu timeline.
Can I prevent or reduce side effects?
Ask your clinician or pharmacist which steps suit you before your shot, and what to do if a reaction bothers you.
How do I treat a side effect?
A pharmacist can tell you what is appropriate for a sore arm, fever or other reaction based on your own health and medicines. Bring a list of what you take.
Are there long-term side effects?
For effects that last or appear later, ask your clinician what has been studied for the vaccine you’re offered and what to do if it happens to you.
What does the vaccine cost, and is it covered?
Medicare’s page says: “You pay nothing if your doctor or other health care provider accepts Assignment for giving you the vaccine.” Assignment means the provider takes the Medicare-approved amount and does not bill you for more than your deductible and coinsurance. The page also notes that amounts you could owe depend on other insurance you have, what your doctor charges, whether your doctor accepts assignment and the type of facility. If you’re charged, ask what the vaccine and visit will cost before you go. Prices differ by pharmacy and change, so check the price directly with the pharmacy or clinic.
What should I ask my clinician before a shot?
- Which formula are you giving, and does it match the current schedule on CDC.gov?
- Which side effects are listed in this vaccine’s prescribing information?
- Does the clotting risk described in the research apply to my health history?
- What should I do if a reaction lasts longer than the label describes?
- Does my medical history change which shot is right for me?
- What will this cost, and is it covered by my plan?
By Gut, Gum and Nail Health Editorial Team
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.