Spikevax (Elasomeran)
mRNA vaccine for the prevention of COVID-19 caused by SARS-CoV-2
Quick Facts About Spikevax
Key Takeaways About Spikevax
- mRNA technology: Spikevax uses nucleoside-modified messenger RNA, not live or inactivated virus, so it cannot cause COVID-19 infection
- Broad eligibility: Approved for use in adults, adolescents, children, and infants from 6 months of age, with dose-adjusted formulations by age group
- Proven efficacy: Phase 3 clinical trials demonstrated approximately 94% efficacy in preventing symptomatic COVID-19 in the original formulation, with updated strain-matched versions continuing to provide protection against severe disease
- Generally mild side effects: Most reactions are injection site pain, fatigue, headache, muscle ache, chills, and fever that resolve within 1–3 days
- Rare but recognised risks: Myocarditis and pericarditis are rare events mostly reported in adolescent and young adult males after the second dose, and anaphylaxis can occur rarely; vaccination sites therefore monitor patients for at least 15 minutes post-injection
What Is Spikevax and What Is It Used For?
Spikevax (elasomeran) is an mRNA vaccine used for active immunisation to prevent COVID-19 caused by SARS-CoV-2 in individuals aged 6 months and older. It works by teaching the immune system to recognise the spike protein of the virus without exposing the body to the actual pathogen.
Spikevax represents one of the first approved vaccines to use messenger RNA (mRNA) technology on a global scale. Unlike traditional vaccines that use weakened or inactivated pathogens, or subunit vaccines that deliver purified viral proteins, Spikevax delivers a strand of genetic code that instructs the body's own cells to temporarily produce a harmless copy of the SARS-CoV-2 spike protein. The immune system then recognises this protein as foreign, mounts a protective response, and develops immunological memory that can be called upon if the real virus is encountered in the future.
The active substance in Spikevax is elasomeran, the International Nonproprietary Name for the mRNA originally identified as mRNA-1273. Each 0.5 mL dose of the original formulation contains 100 micrograms of mRNA embedded in lipid nanoparticles. Spikevax has been adapted multiple times to match circulating variants of SARS-CoV-2; subsequent strain-matched versions have included bivalent formulations and monovalent updates targeting Omicron subvariants such as XBB.1.5, JN.1 and KP.2, delivered under the same brand name.
SARS-CoV-2, the virus that causes COVID-19, emerged in late 2019 and was declared a pandemic by the World Health Organization in March 2020. The virus primarily infects the respiratory tract and can cause a spectrum of illness ranging from asymptomatic infection to life-threatening pneumonia, acute respiratory distress syndrome, thrombotic complications, and death. It has been associated with long-term post-acute sequelae in some patients, commonly referred to as long COVID or post-COVID-19 condition. Spikevax was authorised for emergency use in December 2020 in the United States and granted conditional marketing authorisation in the European Union in January 2021, followed by a full marketing authorisation in 2022.
How Spikevax Works
After intramuscular injection, the lipid nanoparticles (LNPs) containing the mRNA are taken up by cells in the muscle tissue and local lymph nodes, primarily muscle cells and antigen-presenting cells such as dendritic cells. Once inside the cell, the mRNA is released into the cytoplasm, where ribosomes translate it into full-length, pre-fusion-stabilised SARS-CoV-2 spike (S) protein. The mRNA does not enter the cell nucleus and cannot interact with or alter the person's DNA.
The newly synthesised spike protein is displayed on the surface of these cells and is also secreted into the surrounding tissue. Dendritic cells then migrate to regional lymph nodes, where they present fragments of the spike protein to T and B lymphocytes. This triggers a robust immune response involving production of neutralising antibodies that bind the real virus and block it from infecting cells, as well as memory B cells and CD4+ and CD8+ T cells that provide longer-lasting protection, particularly against severe disease.
The mRNA itself is degraded by normal cellular enzymes within days, and the spike protein is cleared shortly thereafter. What remains is the immunological memory necessary to respond rapidly to future exposure to SARS-CoV-2. Evidence from clinical trials and large observational studies has shown that although antibody levels wane over time, memory B cells and T cells generated by vaccination persist and provide durable protection against severe COVID-19, hospitalisation, and death.
Regulatory approval was based primarily on the pivotal COVE trial, a randomised, double-blind, placebo-controlled Phase 3 study of more than 30,000 adult participants. The trial demonstrated an efficacy of approximately 94% in preventing laboratory-confirmed symptomatic COVID-19, with consistent benefit across age, sex, race, and relevant comorbidities. Subsequent real-world effectiveness studies by agencies such as the WHO, ECDC, and CDC have confirmed substantial protection against severe disease, even as new variants have emerged.
Spikevax is a vaccine, not a treatment. It is used to help prevent COVID-19 before exposure. It does not cure an existing SARS-CoV-2 infection and is not a substitute for antiviral therapies such as nirmatrelvir/ritonavir or remdesivir in patients who develop COVID-19.
What Should You Know Before Taking Spikevax?
Before receiving Spikevax, tell your healthcare provider about any allergies, previous severe reactions to vaccines, bleeding disorders, weakened immune system, or current illness with fever. Vaccination should be postponed in people with an acute severe febrile illness, and an observation period of at least 15 minutes after injection is recommended.
Spikevax is given under medical supervision by trained vaccinators. Your healthcare provider will conduct a brief pre-vaccination screening to ensure the vaccine is appropriate for you at this time. This usually involves a short medical history review, questions about any previous vaccine reactions, and an assessment of any current symptoms. Understanding the important precautions before vaccination supports safer, more effective immunisation.
Contraindications
You must not receive Spikevax if:
- You are known to be hypersensitive (allergic) to the active substance elasomeran or to any of the excipients, in particular polyethylene glycol (PEG), which is present in the lipid nanoparticles as PEG2000-DMG (SM-102)
- You have experienced a severe allergic reaction (anaphylaxis) after a previous dose of Spikevax or any other mRNA COVID-19 vaccine containing PEG
If you think you may be allergic to any component of Spikevax, discuss this with your healthcare provider before vaccination. In many cases, an alternative COVID-19 vaccine using different technology (such as a protein subunit vaccine) may be appropriate.
Warnings and Precautions
Talk to your doctor, nurse, or vaccinator before receiving Spikevax if any of the following apply to you:
- Severe allergic reactions: A history of severe or immediate allergic reactions following other vaccines or injectable therapies warrants extra observation and precautions, including immediate access to adrenaline (epinephrine)
- Bleeding disorders or anticoagulant therapy: People taking blood thinners such as warfarin or with conditions like haemophilia may bruise or bleed at the injection site. Vaccination is still possible with careful technique, such as using a fine needle and prolonged pressure after injection
- Weakened immune system: Patients with immunodeficiency or receiving immunosuppressive therapy (including corticosteroids, biologics, chemotherapy, or post-transplant regimens) may produce a weaker immune response. Additional doses may be recommended in line with national vaccination schedules
- Acute severe febrile illness: Vaccination should be postponed in people with a high fever or serious acute infection. Mild illness such as a common cold is not a reason to delay vaccination
- Previous myocarditis or pericarditis: If you have experienced myocarditis or pericarditis after a previous dose of an mRNA vaccine, discuss the risks and benefits with your doctor before receiving another dose
- Fainting (syncope): Fainting can occur before, during, or after any injection. Tell your vaccinator if you have a history of fainting so that appropriate precautions can be taken
- Age considerations: Paediatric and adolescent dosing differs from adult dosing. Ensure the correct age-appropriate formulation is used
Very rare cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) have been reported after vaccination with Spikevax and other mRNA COVID-19 vaccines. These events occur predominantly within 14 days of vaccination, most often after the second dose, and most commonly in adolescent and young adult males. Seek medical attention immediately if you develop chest pain, shortness of breath, rapid or fluttering heartbeat, or palpitations after vaccination. Most reported cases have been mild and resolved with rest and standard anti-inflammatory treatment.
Pregnancy and Breastfeeding
Available evidence from more than one million monitored pregnancies across several large observational studies has shown no increased risk of miscarriage, stillbirth, preterm birth, low birth weight, or congenital malformations associated with mRNA COVID-19 vaccines. COVID-19 itself is associated with increased risks during pregnancy, including preterm delivery, preeclampsia, ICU admission, and maternal death. For these reasons, the WHO, EMA, FDA, CDC, RCOG, and most national obstetric authorities recommend COVID-19 vaccination with Spikevax during any stage of pregnancy, particularly for those at increased risk of exposure or severe disease.
Spikevax can also be given during breastfeeding. There is no evidence that mRNA or lipid nanoparticles are transferred in clinically meaningful amounts into breast milk. Maternal antibodies produced in response to vaccination have been detected in breast milk and may offer passive protection to the infant.
Driving and Using Machines
Spikevax is not expected to have any influence on the ability to drive or operate machinery. However, some people experience short-term side effects such as fatigue, dizziness, or feeling generally unwell for 1 to 2 days after vaccination. If you feel unwell, do not drive or use machines until you feel better.
Spikevax contains sodium but less than 1 mmol (23 mg) per 0.5 mL dose, so it is essentially "sodium-free." It also contains the cryoprotectants trometamol and trometamol hydrochloride, the lipid excipients SM-102, cholesterol, DSPC, and PEG2000-DMG, as well as acetic acid, sodium acetate trihydrate, sucrose, and water for injections. Allergies to PEG (polyethylene glycol) are rare but are the most important known cause of severe allergic reactions to mRNA vaccines.
Children and Adolescents
Spikevax is authorised in most jurisdictions for active immunisation in individuals aged 6 months and older, using dose-adjusted formulations:
- Children 6 months through 5 years: 25 micrograms per dose
- Children 6 through 11 years: 50 micrograms per dose
- Adolescents 12 years and older and adults: 100 micrograms per primary dose or 50 micrograms per booster dose
Paediatric doses are delivered using appropriately diluted multidose vials clearly labelled with the intended age group. Your vaccinator will verify the correct formulation and dose.
How Does Spikevax Interact with Other Drugs?
Spikevax can be given together with most other vaccines and medicines, but immunosuppressive therapies may reduce its effectiveness, and anticoagulants can slightly increase the risk of injection-site bleeding or bruising. Always tell your vaccinator about all medicines, supplements, and recent vaccinations before receiving Spikevax.
Because Spikevax works by stimulating an immune response rather than altering circulating drug levels or metabolism, classical drug-drug interactions of the type seen with oral medications are not expected. However, certain medicines, medical conditions, and recent vaccinations can influence the safety or effectiveness of Spikevax. It is always important to inform your healthcare provider of all medications you are taking, including over-the-counter products, supplements, and biologic therapies.
Major Interactions
| Interacting Drug/Class | Effect | Recommendation |
|---|---|---|
| Systemic corticosteroids (high dose) | May blunt the antibody and T-cell response to the vaccine, particularly at daily doses equivalent to 20 mg of prednisone or more | Vaccination is still recommended; additional doses may be advised per national immunocompromised guidelines |
| Biologic immunosuppressants (e.g., rituximab, anti-TNF agents, JAK inhibitors) | Reduced humoral response; rituximab in particular can substantially impair antibody formation for 6–12 months | Where clinically possible, time vaccination before starting therapy or between cycles; follow specialist advice |
| Chemotherapy agents | May impair immune response during active treatment | Coordinate timing with oncology team; do not delay vaccination unnecessarily in high-risk patients |
| Anticoagulants (e.g., warfarin, DOACs) and antiplatelet agents | Increased risk of bruising or bleeding at the injection site | Use a fine needle, apply firm pressure for at least 2 minutes after injection; do not discontinue anticoagulants for vaccination |
| Other vaccines (including inactivated influenza and pneumococcal) | Can generally be co-administered without clinically meaningful effect on immunogenicity or safety | Different injection sites should be used; follow national co-administration guidance |
| Anti-SARS-CoV-2 monoclonal antibodies | May theoretically interfere with vaccine-induced immune response | Consult local guidelines on timing; some authorities recommend a minimum interval after therapeutic antibody use |
Minor Interactions
Most routine medications used for chronic conditions, including antihypertensives, statins, oral antidiabetic agents, thyroid hormones, antidepressants, and contraceptives, do not interact meaningfully with Spikevax. Paracetamol (acetaminophen) and ibuprofen may be used to manage post-vaccination symptoms such as fever and pain; however, international authorities generally recommend not taking antipyretics prophylactically before vaccination because early laboratory evidence suggested a possible modest reduction in antibody response. Treatment of symptoms after they occur is considered safe and appropriate.
Clinical studies support co-administration of Spikevax with inactivated seasonal influenza vaccines in separate anatomical sites. This can improve vaccination coverage, although mildly increased local and systemic reactions (such as injection-site pain and headache) have been reported with simultaneous administration.
What Is the Correct Dosage of Spikevax?
Adult primary doses of Spikevax are typically 100 micrograms (0.5 mL), while booster doses are 50 micrograms (0.25 mL). Paediatric doses are reduced according to age, starting from 25 micrograms for children aged 6 months to 5 years. The vaccine is given as an intramuscular injection, usually into the deltoid muscle of the upper arm.
Spikevax is given as an intramuscular injection by a qualified healthcare professional. Doses must not be injected intravenously, subcutaneously, or intradermally. The exact dose and schedule depend on age, immune status, and prior vaccination history. National immunisation programmes continually update recommendations, and the most current dosing advice should be obtained from your healthcare provider or public health authority.
Adults
Primary immunisation: 100 micrograms (0.5 mL)
Adults aged 18 years and older who have never been vaccinated against COVID-19 typically receive one or two primary doses of 100 micrograms administered at an interval of approximately 4 weeks (28 days), in line with national guidance. Single-dose primary regimens are now common in many jurisdictions for people without prior exposure and who are not immunocompromised.
Booster dose: 50 micrograms (0.25 mL)
A booster dose of 50 micrograms is commonly recommended at least 3 to 6 months after the last primary or booster dose. Updated strain-matched formulations (targeting currently circulating variants) are preferred for booster use where available. Annual boosting is recommended for people at higher risk of severe disease.
Children and Adolescents
Adolescents 12–17 years
Primary immunisation uses the adult 100-microgram dose (0.5 mL) in most jurisdictions, with boosters of 50 micrograms. Benefits and risks, including the rare risk of myocarditis, should be discussed before vaccination.
Children 6–11 years
Primary and booster doses of 50 micrograms (0.5 mL of a diluted formulation) are used. Myocarditis appears to be less common in this age group than in 12–17 year olds.
Infants and young children 6 months–5 years
A reduced dose of 25 micrograms (0.25 mL of a diluted paediatric formulation) is used. The primary course is usually two doses given approximately 4 weeks apart. Booster doses may be recommended for children with underlying medical conditions.
Elderly
No dose adjustment is required for older adults. Adults aged 65 years and older are at higher risk of severe COVID-19 and are a priority group for primary vaccination and regular boosters. Clinical trials showed consistent efficacy and an acceptable safety profile in older adults, with slightly fewer reactogenic side effects such as fever and fatigue compared with younger adults.
Immunocompromised Patients
People with significant immunosuppression (for example, solid organ transplant recipients, those on high-dose immunosuppressive therapy, patients with advanced HIV, and those with certain primary immunodeficiencies) often require an additional primary dose and more frequent boosters. National guidelines typically recommend a 3-dose primary series followed by booster doses for this population.
Missed Dose
If a scheduled dose is missed, the next dose should be administered as soon as possible. There is no need to restart the vaccination series. Your vaccinator will confirm the appropriate timing of subsequent doses based on your overall vaccination history.
Overdose
Administration of doses higher than the recommended amount has been reported in rare cases without an identified safety signal. In the event of a confirmed overdose, monitoring for vaccine-related side effects and symptomatic treatment are recommended. Consult a healthcare professional if an overdose is suspected.
What Are the Side Effects of Spikevax?
The most common side effects of Spikevax are injection-site pain, fatigue, headache, muscle pain, chills, fever, and joint pain, typically lasting 1–3 days. Rare but recognised risks include anaphylaxis, myocarditis, and pericarditis. Seek urgent medical care for severe allergic reactions or chest pain, shortness of breath, or palpitations after vaccination.
Like all medicines, Spikevax can cause side effects, although not everybody experiences them. Most side effects reflect the expected action of the vaccine on the immune system, are mild to moderate in intensity, and resolve without intervention within a few days. Understanding which side effects are common, which are rare, and which require immediate medical attention helps you make an informed decision and respond appropriately if symptoms develop.
Go to an emergency department or call emergency services immediately if you experience any of the following after Spikevax: difficulty breathing, swelling of the face or throat, a rapid heartbeat, a severe skin rash, dizziness or weakness suggesting anaphylaxis, chest pain, palpitations, or unexplained shortness of breath. These symptoms may indicate anaphylaxis, myocarditis, or pericarditis — all of which require urgent assessment.
Serious Side Effects
The following side effects have been reported in clinical trials and post-marketing surveillance. Frequencies are derived from EMA-approved Summary of Product Characteristics data and WHO pharmacovigilance reports:
Very Common (affects more than 1 in 10 people)
- Pain, swelling, redness, or tenderness at the injection site
- Swollen or tender lymph nodes (lymphadenopathy) under the arm on the injected side
- Headache
- Fatigue or feeling tired
- Muscle aches (myalgia) and joint pain (arthralgia)
- Chills and fever
- Nausea and sometimes vomiting
Common (affects up to 1 in 10 people)
- Injection-site rash, hives, or delayed redness (sometimes called "COVID arm"), typically appearing 7–10 days after injection and resolving within a week
- Diarrhoea
- Dizziness
- Palpitations or awareness of heartbeat
Uncommon (affects up to 1 in 100 people)
- Facial swelling, particularly in people who have had dermal fillers
- Itching at the injection site
- Transient Bell's palsy (temporary one-sided facial weakness), although a clear causal link has not been established
Rare or Very Rare (affects up to 1 in 1,000 or fewer)
- Anaphylaxis — severe, life-threatening allergic reaction, typically within minutes to hours of vaccination
- Myocarditis and pericarditis, especially in adolescent and young adult males and most often within 14 days of the second dose
- Capillary leak syndrome — very rare reports, primarily in people with a prior history of the condition
- Severe skin reactions such as erythema multiforme in very rare cases
- Extensive swelling of the vaccinated limb
Myocarditis and Pericarditis Explained
Myocarditis is inflammation of the heart muscle; pericarditis is inflammation of the membrane surrounding the heart. Cases reported after mRNA COVID-19 vaccines, including Spikevax, have most commonly been diagnosed in adolescent and young adult males, typically within 14 days of vaccination, and most often after the second dose. Observational data suggest an approximate incidence on the order of 1 to 5 cases per 100,000 vaccinations in the highest-risk group, with most cases being mild, responsive to standard anti-inflammatory treatment, and resolving within a few weeks.
Importantly, the risk of myocarditis is substantially higher from SARS-CoV-2 infection itself than from vaccination, and myocarditis associated with infection tends to be more severe. Long-term follow-up studies continue to monitor cardiovascular outcomes after mRNA vaccination. Symptoms to watch for include chest pain or pressure, shortness of breath, palpitations, a feeling of irregular or rapid heartbeat, or reduced exercise tolerance in the days to weeks after vaccination. Anyone experiencing such symptoms should seek medical evaluation promptly.
Managing and Reporting Side Effects
Mild side effects can usually be managed at home with rest, adequate hydration, and over-the-counter paracetamol (acetaminophen) or ibuprofen. Cool compresses applied to the injection site can ease local pain and swelling. Most symptoms resolve within 1 to 3 days. If symptoms persist beyond a week, worsen, or are accompanied by red-flag signs such as high fever unresponsive to antipyretics, chest pain, difficulty breathing, or severe headache, contact your healthcare provider.
Suspected adverse events should be reported to national pharmacovigilance systems. In the EU, this is typically done through national regulatory agencies linked to the EudraVigilance database; in the United States, through the Vaccine Adverse Event Reporting System (VAERS); and globally, data flow into the WHO VigiBase system. Your reports help regulators monitor the real-world safety of Spikevax.
How Should You Store Spikevax?
Unopened vials of Spikevax must be stored frozen at minus 50°C to minus 15°C. Thawed unpunctured vials can be kept refrigerated at 2°C to 8°C for up to 30 days. After first use, the multidose vial should be used within approximately 12 hours. Patients do not handle storage; vaccination sites manage the cold chain.
Spikevax is a lipid nanoparticle formulation of mRNA and is sensitive to temperature, light, and agitation. Because of this, strict cold-chain management is required from manufacturing to administration. As an individual receiving the vaccine, you will not be responsible for storing Spikevax. However, understanding the storage principles explains why vaccination is delivered through a carefully organised network of clinics and why there can sometimes be restrictions on how vials are used.
Unopened, unpunctured vials of Spikevax must be stored frozen at a temperature between −50°C and −15°C in the original packaging, protected from light. The vials must not be stored on dry ice or at temperatures below −50°C. When thawed, an unpunctured vial can be kept refrigerated at 2°C to 8°C for up to 30 days. During this 30-day period, the vial may be handled at temperatures up to 25°C for a cumulative total of 24 hours, which includes transport between sites.
Once the vial is first punctured (pierced with a needle to withdraw a dose), the remaining content must be used within a defined window — typically up to 12 hours at 2°C to 25°C, depending on the specific formulation and national guidance. The time and date of first use are recorded on the vial label. Vials should not be refrozen once thawed, and the vaccine must not be diluted further than specified by the manufacturer (except for paediatric dose preparation according to approved protocols).
Spikevax is a white to off-white dispersion. Before drawing each dose, healthcare workers inspect the vial for particulate matter or discolouration and confirm the expiration date and stability tracking. Vials showing cracks, leakage, clumping, or discolouration must not be used.
Unused product and waste are disposed of in accordance with local requirements for biological materials. This is typically performed at the vaccination clinic or a centralised pharmacy, not by patients.
What Does Spikevax Contain?
Each 0.5 mL dose of Spikevax contains 100 micrograms of elasomeran, a nucleoside-modified messenger RNA encoding the SARS-CoV-2 spike protein. The mRNA is encapsulated in lipid nanoparticles containing SM-102, cholesterol, DSPC, and PEG2000-DMG, along with excipients including trometamol, sucrose, acetic acid, and water for injections. Spikevax does not contain live virus, preservatives, eggs, gelatin, latex, or aluminium.
The active ingredient in Spikevax is elasomeran, a single-stranded, 5'-capped messenger RNA produced by cell-free in vitro transcription from a DNA template. The sequence encodes the viral spike (S) glycoprotein of SARS-CoV-2, stabilised in the pre-fusion conformation by two proline substitutions. In the original formulation, each 0.5 mL dose contained 100 micrograms of elasomeran, corresponding to a concentration of 0.2 mg/mL in the primary formulation or 0.1 mg/mL in diluted paediatric and booster formulations, depending on the specific presentation.
Active Ingredient
- Elasomeran — nucleoside-modified mRNA encoding the SARS-CoV-2 spike glycoprotein. In updated strain-matched formulations, the mRNA sequence has been adapted to match circulating variants (for example, famtozinameran for Omicron BA.4/BA.5 bivalent formulations, or andusomeran-containing formulations for XBB.1.5)
Excipients (Inactive Ingredients)
The formulation contains the following inactive ingredients, the primary purpose of which is to deliver the mRNA safely to cells and to stabilise the product during storage:
- SM-102 — proprietary ionisable lipid that forms the core of the lipid nanoparticle
- Cholesterol — structural lipid component of the nanoparticle
- 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) — phospholipid contributing to nanoparticle stability
- PEG2000-DMG (1,2-dimyristoyl-rac-glycero-3-methoxy-polyethylene glycol-2000) — PEGylated lipid that provides colloidal stability
- Trometamol and trometamol hydrochloride — buffering agents
- Sodium acetate trihydrate and acetic acid — additional buffer components (in some formulations)
- Sucrose — cryoprotectant that protects the nanoparticles during freezing
- Water for injections — solvent
Important Composition Notes
Several aspects of the composition are clinically relevant:
- No live virus: Spikevax cannot cause COVID-19 because it does not contain any SARS-CoV-2 virus, attenuated or otherwise. It contains only a piece of mRNA
- PEG content: Polyethylene glycol (PEG) is the most likely trigger of the rare anaphylactic reactions reported with mRNA vaccines. People with a history of PEG allergy should discuss alternative vaccines with their healthcare provider
- Sodium content: Each dose contains less than 1 mmol (23 mg) of sodium and is therefore essentially "sodium-free"
- Gluten, lactose, egg, gelatin, latex, and aluminium: Spikevax does not contain any of these substances and is suitable for people with related allergies or dietary restrictions
Appearance and Packaging
Spikevax is a white to off-white dispersion supplied in multidose vials of approximately 2.5 mL or 5 mL, each sealed with a rubber stopper and an aluminium overseal with a flip-off cap. Once thawed, the product may contain white or translucent product-related particulates, which do not affect safety or potency. Vials are clearly labelled with the formulation strength, expiration date, and intended age group when applicable.
Frequently Asked Questions About Spikevax
Spikevax (elasomeran) is a messenger RNA (mRNA) vaccine used to prevent COVID-19 caused by the SARS-CoV-2 virus. It contains a short piece of mRNA encapsulated in lipid nanoparticles that instructs cells to temporarily produce a harmless version of the viral spike protein. The immune system recognises this protein as foreign and develops antibodies, memory B cells, and T cells that provide protection if the real virus is encountered in the future. The mRNA is broken down by normal cellular processes within days and does not interact with your DNA.
The most common side effects include pain, swelling, and redness at the injection site; tiredness; headache; muscle and joint pain; chills; fever; nausea; and swollen lymph nodes under the arm. These reactions are usually mild to moderate and resolve within 1 to 3 days. Side effects tend to be more noticeable after the second dose or a booster. Paracetamol or ibuprofen can help manage discomfort but should generally be taken only if symptoms occur, not routinely before vaccination.
Spikevax is given as an intramuscular injection, most commonly into the deltoid muscle of the upper arm. It must not be injected intravenously, intradermally, or subcutaneously. Injection is performed by qualified healthcare professionals in clinics, pharmacies, vaccination centres, or authorised outreach settings. After injection, patients are typically observed for at least 15 minutes (30 minutes if there is a relevant allergy history) to monitor for immediate reactions.
No. Spikevax cannot give you COVID-19 because it does not contain live or inactivated SARS-CoV-2 virus. It contains only a short piece of mRNA that encodes the spike protein, not the complete virus. Some people may develop flu-like symptoms such as fever, chills, or muscle aches for a day or two after vaccination, but these are signs of the immune system responding to the vaccine rather than evidence of an actual infection.
Large real-world studies involving more than a million monitored pregnancies have not identified increased risks of miscarriage, stillbirth, preterm birth, or congenital abnormalities with mRNA COVID-19 vaccines such as Spikevax. Because COVID-19 itself carries increased risks during pregnancy, major health authorities including the WHO, EMA, FDA, and CDC recommend COVID-19 vaccination at any stage of pregnancy. Spikevax can also be given during breastfeeding, and vaccine-induced antibodies may provide passive protection to the infant.
Myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) are rare but recognised side effects of mRNA COVID-19 vaccines. They occur most often in adolescent and young adult males, typically within 14 days of the second dose, and most cases have been mild and resolved with standard treatment. Observational data suggest an incidence on the order of 1 to 5 cases per 100,000 vaccinations in the highest-risk group. Importantly, the risk of myocarditis is substantially higher from SARS-CoV-2 infection itself than from vaccination. Seek medical attention promptly if you develop chest pain, shortness of breath, or palpitations after vaccination.
Unopened vials of Spikevax must be stored frozen at between −50°C and −15°C. Once thawed, unpunctured vials can be kept refrigerated at 2°C to 8°C for up to 30 days and at room temperature (up to 25°C) for a cumulative total of 24 hours. After the first puncture, the remaining vaccine should be used within approximately 12 hours. All storage and handling are managed by the vaccination site, not by individual patients.
References
- European Medicines Agency (EMA). Spikevax (elasomeran) — Summary of Product Characteristics and EPAR. Available at: ema.europa.eu/en/medicines/human/EPAR/spikevax. Accessed December 2025.
- U.S. Food and Drug Administration (FDA). SPIKEVAX (COVID-19 Vaccine, mRNA) — Prescribing Information. Licensed January 2022; most recent update 2025.
- Baden LR, El Sahly HM, Essink B, et al. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. N Engl J Med. 2021;384(5):403-416. doi:10.1056/NEJMoa2035389
- El Sahly HM, Baden LR, Essink B, et al. Efficacy of the mRNA-1273 SARS-CoV-2 Vaccine at Completion of Blinded Phase. N Engl J Med. 2021;385(19):1774-1785.
- Ali K, Berman G, Zhou H, et al. Evaluation of mRNA-1273 SARS-CoV-2 Vaccine in Adolescents. N Engl J Med. 2021;385(24):2241-2251.
- Creech CB, Anderson E, Berthaud V, et al. Evaluation of mRNA-1273 Covid-19 Vaccine in Children 6 to 11 Years of Age. N Engl J Med. 2022;386(21):2011-2023.
- Anderson EJ, Creech CB, Berthaud V, et al. Evaluation of mRNA-1273 Vaccine in Children 6 Months to 5 Years of Age. N Engl J Med. 2022;387(18):1673-1687.
- World Health Organization (WHO). Interim recommendations for use of the Moderna mRNA-1273 vaccine against COVID-19. Strategic Advisory Group of Experts on Immunization (SAGE).
- European Centre for Disease Prevention and Control (ECDC). COVID-19 Vaccine Tracker and guidance documents.
- Oster ME, Shay DK, Su JR, et al. Myocarditis Cases Reported After mRNA-Based COVID-19 Vaccination in the US From December 2020 to August 2021. JAMA. 2022;327(4):331-340.
- Magnus MC, Gjessing HK, Bjorndal A, et al. Covid-19 Vaccination during Pregnancy and First-Trimester Miscarriage. N Engl J Med. 2021;385(21):2008-2010.
- Centers for Disease Control and Prevention (CDC). COVID-19 Vaccination Clinical and Professional Resources.
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