2023 COVID Vaccine Side Effects: What You Need to Know
Insights on soothing mild discomfort help make days after your booster more manageable.
The updated COVID-19 vaccine for fall 2023 has been rigorously tested and is designed to target the latest strains of the virus. As many people consider whether to receive this booster, questions about its side effects remain common. Understanding what to expect can help you make informed decisions and ease concerns about your health and safety.
Table of Contents
- How Safe is the 2023 COVID Vaccine?
- Potential Side Effects of the 2023 Vaccine
- Comparison With Earlier COVID Vaccines
- COVID Vaccine vs. Flu Vaccine Side Effects
- Who is More Likely to Experience Side Effects?
- Rare But Serious Side Effects
- Should I Be Worried About Side Effects?
- Frequently Asked Questions
How Safe is the 2023 COVID Vaccine?
The 2023 COVID-19 vaccine booster is a monovalent vaccine that targets the XBB.1.5 variant, the latest prominent version of the Omicron strain. Health experts stress it uses familiar technology from previous vaccines and boosters, simply updated to better match circulating viruses—just as annual flu vaccines are updated.
Rigorous testing has shown these new boosters remain very safe. Side effects observed so far are consistent with those seen in previous COVID-19 vaccine releases, and health authorities report no unexpected or more severe reactions associated with the 2023 update . The safety profile continues to be monitored by agencies such as the FDA and CDC.
Potential Side Effects of the 2023 Vaccine
Research shows that 30–90% of people who receive the COVID-19 vaccine experience at least one side effect, typically within the first one to three days after inoculation. These are generally mild and short-lived, signaling your immune system’s natural response.
Most Common Side Effects
- Pain, swelling, or redness at the injection site
- Tiredness (fatigue)
- Headache
- Muscle pain
- Chills
- Nausea
- Fever
These symptoms are not unique to the updated booster; they have been observed with previous COVID-19 vaccine doses as well . Dr. Shira Doron, chief infection control officer for Tufts Medicine, emphasizes: “If you have side effects, they’re usually due to your immune system responding to the vaccine, which is how vaccines work.”
What others are reading
Other Less Common Reactions:
- Joint pain
- Swollen lymph nodes (especially under the arm where the shot was given)
- Nausea/vomiting
For infants and toddlers, symptoms can include increased irritability, decreased appetite, and drowsiness .
Comparison With Earlier COVID Vaccines
The technology behind the 2023 vaccine booster is the same as used previously. The most common side effects and their frequency have not changed markedly with the latest update, according to published health authority data. Some people may notice a slightly different mixture or intensity of symptoms based on their immune response, but there are no new or previously unseen reactions tied specifically to the 2023 version .
| Symptom | Frequency (COVID-19) | Frequency (Flu Vaccine, for comparison) |
|---|---|---|
| Weakness | 23.7% | 8.6% |
| Headache | 19.1% | 6.1% |
| Muscle pain | 18.9% | 4.0% |
| Fever | 9.5% | — |
| Chills | 8.1% | — |
COVID Vaccine vs. Flu Vaccine Side Effects
COVID-19 vaccines are often compared to annual influenza vaccines in terms of side effect patterns. While both cause immune-related symptoms, studies indicate COVID-19 vaccines are more likely to induce systemic effects such as chills, fever, and muscle pain. The majority of flu vaccine reactions are confined to localized pain or swelling at the injection site .
Main Differences at a Glance
- COVID-19 vaccines: More frequent systemic side effects (e.g., fatigue, chills, fever).
- Flu vaccines: More commonly just local site reaction, lower systemic effect rates.
Who is More Likely to Experience Side Effects?
Not everyone will have side effects—and some people may have different experiences from dose to dose. Factors that increase likelihood include:
- Age: Younger individuals under 55 are more likely to have local and systemic reactions.
- Sex: Females tend to report side effects more frequently than males.
- Medical history: Individuals without underlying health conditions often have a slightly higher rate of mild side effects.
According to research, healthier individuals and those with more robust immune systems may be more likely to experience prominent reactions, as their immune response is more pronounced .
Rare But Serious Side Effects
The overwhelming majority of COVID-19 vaccine side effects are mild and self-limited. However, like any medical product, there are rare but potentially severe reactions. These have been carefully tracked by public health agencies, and all evidence to date shows that benefits of vaccination vastly outweigh the potential risks.
Severe Allergic Reactions
- Anaphylaxis: A severe, potentially life-threatening allergic reaction, identified by difficulty breathing, rapid heartbeat, or swelling of lips or throat. Occurs very rarely (approx. 2–5 cases per million doses) .
- People with a history of severe allergies to vaccine ingredients are monitored for at least 30 minutes after receiving a shot.
Blood Clots and Thrombosis
- Relevant mainly to the Johnson & Johnson (Janssen) vaccine: rare cases of blood clots (thrombosis) with low platelets (TTS) observed, primarily in females under 50.
- Typical symptoms occur within 21 days of vaccination: shortness of breath, chest pain, leg swelling, persistent headache, blurred vision, or unusual bruising or tiny red spots away from the injection site .
Guillain-Barré Syndrome
- Another rare event associated mainly with the J&J vaccine (but not mRNA vaccines): immune-related nerve damage or weakness, usually in males 50+ within two weeks of vaccination.
- Symptoms warrant medical attention: muscle weakness or tingling that spreads, trouble walking, facial paralysis, or vision changes .
When to Seek Medical Attention
- If you experience pronounced allergic symptoms (trouble breathing, swelling of face/lips), seek emergency care.
- If you develop severe headache, leg pain, vision changes, or unexplained bruising elsewhere on your body within 2–4 weeks of vaccination, contact your doctor promptly.
- For persistent high fever, difficulty moving, or urinary issues, medical follow-up is recommended.
Should I Be Worried About Side Effects?
Expert consensus is clear: side effects are generally mild, a sign that your immune system is mounting a response, and rarely last longer than a few days. Not having side effects does not mean your body is not building protection—everyone reacts differently.
Dr. Ogbuagu, an infectious diseases specialist at Yale Medicine, reassures: “The new booster is just as safe as previous COVID-19 vaccines; most side effects are mild and temporary.” Minor side effects such as sore arms, headache, and fatigue often resolve without any intervention .
Ways to Ease Temporary Side Effects
- Rest as needed during the first 48 hours after your shot.
- Apply a clean, cool compress at the injection site to minimize pain and swelling.
- If approved by your healthcare provider, consider over-the-counter pain relievers for discomfort (such as acetaminophen or ibuprofen).
- Stay well hydrated.
- If symptoms persist beyond a few days or worsen, consult your healthcare provider.
It’s important to note: Even if you don’t experience side effects, you are still building immune protection against COVID-19.
Frequently Asked Questions (FAQs)
Q: Is it normal to have side effects after the COVID-19 vaccine?
A: Yes. Side effects such as pain at the injection site, tiredness, or mild fever are common and show your body is building protection.
Q: How soon do symptoms appear, and how long do they last?
A: Most side effects start within 1–3 days after vaccination and typically last 1–3 days.
Q: What should I do if I have no side effects after getting the vaccine?
A: Having no side effects is also normal. Your immune system is still developing protection even if you don’t notice symptoms.
Q: Who experiences more side effects?
A: Younger adults, females, and those without preexisting health concerns report more side effects overall, but anyone can experience them.
Q: Should I be worried about rare but serious side effects?
A: Serious side effects like severe allergic reactions or blood clots are extremely rare. The benefits of the vaccine in preventing COVID-19 far outweigh the risks.
Q: Can COVID-19 vaccines cause long-term issues?
A: No evidence suggests long-term side effects. Vaccine safety is monitored continually, and data so far is very reassuring.
Q: When should I contact a doctor after vaccination?
A: Seek medical help if you develop severe chest pain, shortness of breath, leg swelling, severe headache, facial drooping, trouble moving, or allergic symptoms like swelling of face/throat.
Summary
The 2023 COVID-19 vaccine boosters use the same technology as previous releases but have been updated for the latest virus variants. Most people will have no or only mild side effects, such as pain at the injection site, tiredness, or low-grade fever. Serious side effects are exceedingly rare, and vaccination remains the most effective tool to prevent severe illness, hospitalization, and death from COVID-19.
Vaccines continue to be monitored for safety by leading health agencies. If you have any questions or concerns about your personal risk, discuss them with your healthcare provider. Stay informed—your health matters.
References
- https://www.cdc.gov/vaccine-safety/vaccines/covid-19.html
- https://www.goodhousekeeping.com/health/a45534145/2023-covid-vaccine-side-effects/
- https://www.ama-assn.org/public-health/infectious-diseases/what-doctors-wish-patients-knew-about-johnson-johnson-vaccine
- https://www.nature.com/articles/s41598-024-56561-w
- https://www.goodhousekeeping.com/health/a61830829/covid-flirt-lb1-variant-symptoms/
- https://www.yalemedicine.org/news/covid-19-vaccine-comparison
- https://www.ncoa.org/article/what-is-the-latest-covid-vaccine-guidance-for-older-adults/
- https://www.cbsnews.com/news/fda-covid-vaccine-mrna-heart-side-effects-warning-label/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10278957/
- https://www.heart.org/en/coronavirus/coronavirus-questions/questions-about-covid-19-vaccination
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