Subcutaneous (Subcut)

Subcutaneous administration involves injecting the vaccine into the fatty tissue, typically over the triceps in people aged 12 months and older, or in the anterolateral thigh for people younger than age 12 months. CDC offers a short training video about subcutaneous vaccine administration. Please refer to the JYNNEOS Preparation & Administration Summary (Standard Regimen) for further details on subcutaneous vaccine administration.

Interchangeability of Dosing Regimens

When necessary in eligible individuals, the dosing regimens are interchangeable. For example, a person aged 18 years or older who received one JYNNEOS vaccine dose with the standard subcutaneous regimen may receive a second dose with the alternative intradermal regimen at the recommended interval (i.e., 28 days) to complete the vaccination series. Another example is a person who received the first dose intradermally, had a robust local reaction, and refuses a second dose unless given subcutaneously. In this situation, that second dose can be given subcutaneously.

Coadministration of JYNNEOS Vaccine with Other Vaccines

Currently, there are no data on administering JYNNEOS vaccine at the same time as other vaccines. Because JYNNEOS is based on a live, attenuated non-replicating orthopoxvirus, JYNNEOS typically may be administered without regard to timing of most other vaccines. This includes simultaneous administration of JYNNEOS and other vaccines, including influenza vaccine, on the same day, but at different anatomic sites if possible.

However, there are additional considerations if administering a COVID-19 vaccine. (Interim Clinical Considerations for Use of COVID-19 Vaccines)

  • There is no required minimum interval between receiving any COVID-19 vaccine and an orthopoxvirus vaccine, either ACAM2000 or JYNNEOS vaccine (e.g., for mpox prevention), regardless of which vaccine is administered first.
  • Use of JYNNEOS vaccine should be prioritized over ACAM2000 when co-administering a COVID-19 vaccine and an orthopoxvirus vaccine.
  • People, particularly adolescent and young adult males, who are recommended to receive both vaccines might consider waiting 4 weeks between vaccines. This is because of the observed risk for myocarditis and pericarditis after receipt of ACAM2000 orthopoxvirus vaccine and COVID-19 vaccines and the hypothetical risk for myocarditis and pericarditis after JYNNEOS vaccine. However, if a patient’s risk for mpox or severe disease due to COVID-19 is increased, administration of mpox and COVID-19 vaccines should not be delayed.

Best practices for multiple injections include:

  • Label each syringe with the name and the dosage (amount) of the vaccine, lot number, initials of the preparer, and exact beyond-use time, if applicable.
  • Administer each injection in a different injection site; separate injection sites by 1 inch or more, if possible.
  • Administer the JYNNEOS vaccine and vaccines that may be more likely to cause a local reaction in different limbs, if possible.

Review ACIP’s general best practices and Epidemiology and Prevention of Vaccine-Preventable Diseases (CDC Pink Book) for further information.

Coadministration of JYNNEOS vaccine with the tuberculin skin test

Currently, there are no data on administering JYNNEOS vaccine at the same time as the tuberculin skin test (TST). While JYNNEOS is a live virus vaccine, it is non-replicating and its effect on the response to the TST may not be the same as for live, replicating virus vaccines such as measles-mumps-rubella (MMR).

If a delay in the TST would cause substantial burden (e.g., preventing a person from working because of pre-employment screening policies) then the TST should not be delayed. If delays in the TST will not cause substantial burden, a delay of at least 4 weeks after JYNNEOS vaccination is preferred.

The TST can be performed at the same time as JYNNEOS vaccination and any sequence of vaccination and the TST may be used. If the JYNNEOS vaccine and the TST are administered on the same day, the vaccine and the TST should be administered on different forearms, one on the left and one on the right.  The location of each injection site should be recorded in order to read the TST result from the correct forearm. If the JYNNEOS vaccine and the TST are administered on the same forearm, the sites of injection should be separated by 8–10 centimeters (that is, 3–4 inches) along the length of the forearm, to reduce likelihood of overlap of any reactions from the two injections, and the location of each injection site and the antigen should be recorded.

For patients who have symptoms or signs of active tuberculosis (TB), all tests and examinations for TB diagnosis should be pursued without delay, regardless of JYNNEOS vaccination.

Patient Counseling

Pre-vaccination Counseling

Recipients should be informed of the risks and benefits of JYNNEOS prior to vaccination. Healthcare providers should determine the medical history of recipients to appropriately decide whether to administer the vaccine subcutaneously or intradermally. Recipients should be counseled about possible side effects from vaccination and be provided with a JYNNEOS vaccine information statement (VIS)

Side effects after vaccination can vary from person to person. Before vaccination, each recipient should be counselled on the possibility of experiencing the following side effects:

Local Side Effects:

  • Erythema
  • Pain
  • Edema
  • Pruritis
  • Hyperpigmentation
  • Induration

Systemic Side Effects:

  • Fatigue
  • Headache
  • Myalgias
  • Nausea
  • Chills
  • Fever

Local side effects may be more severe with intradermal administration compared with subcutaneous administration. Side effects may appear soon after vaccination, and some local reactions, such as hyperpigmentation, may persist for several weeks or months. One study

Post-vaccination Counseling

Local and systemic reactions experienced after vaccination may be managed conservatively. Evidence does not support the use of antipyretics before or at the time of vaccination. However, they can be used for the treatment of fever and local discomfort that might occur following vaccination. Topical emollients, cold compresses, and oral antihistamines may be used to treat local side effects as needed. Do NOT apply topical corticosteroids or antihistamines to local reactions. Weeping or open wounds should be covered by a sterile gauze or bandage. If symptoms persist 28 days after receiving the first dose, the second dose should be placed intradermally in the contralateral forearm.

Given the unknown effectiveness of vaccination in this outbreak, people who are vaccinated should continue to take steps to protect themselves from infection by avoiding close, skin-to-skin contact, including intimate contact, with someone who has mpox.

Clinical studies have not detected an increased risk for myopericarditis in recipients of JYNNEOS. However, people with underlying heart disease or three or more major cardiac risk factors should be counseled about the theoretical risk for myopericarditis following vaccination with JYNNEOS, given the uncertain etiology of myopericarditis associated with replication-competent smallpox vaccines such as ACAM2000.

Safety

Contraindications and precautions

People presenting with minor illnesses, such as a cold, may be vaccinated. People who are moderately or severely ill should usually wait until they have recovered to their baseline state of health before vaccination. A person offered JYNNEOS vaccine due to an exposure to mpox virus or disease should be vaccinated regardless of pregnancy, breastfeeding, or weakened immune system.

Vaccine providers, particularly when vaccinating adolescents, should consider observing patients (with patients seated or lying down) for 15 minutes after vaccination to decrease the risk for injury should they faint. If syncope develops, patients should be observed until the symptoms resolve.

CDC considers vaccination with JYNNEOS to be either contraindicated (not recommended) or a precaution in the following situations.

Table 3. Contraindications and Precautions for Use of JYNNEOS Vaccine

Medical condition or history


Medical condition or history

Medical condition or history

History of a severe allergic reaction (e.g., anaphylaxis) after a previous dose of JYNNEOS


Medical condition or history

History of a severe allergic reaction (e.g., anaphylaxis) after a previous dose of JYNNEOS

Do not vaccinate. Referral to an allergist-immunologist should be considered to assess the risks versus benefits of administering a dose.


Suggested action(s)

Do not vaccinate. Referral to an allergist-immunologist should be considered to assess the risks versus benefits of administering a dose.

History of severe allergic reaction (e.g., anaphylaxis) following receipt of gentamicin or ciprofloxacin1


Medical condition or history

History of severe allergic reaction (e.g., anaphylaxis) following receipt of gentamicin or ciprofloxacin1

Discuss risks and benefits with potential recipients. Patients may be vaccinated with a 30-minute observation period following administration.

Alternatively, vaccination may be delayed until an allergist-immunologist is consulted, but the impact of delaying vaccination should be considered.


Suggested action(s)

Discuss risks and benefits with potential recipients. Patients may be vaccinated with a 30-minute observation period following administration.

Alternatively, vaccination may be delayed until an allergist-immunologist is consulted, but the impact of delaying vaccination should be considered.

History of severe allergic reaction (e.g., anaphylaxis) to chicken or egg protein AND currently avoiding exposure to all chicken or egg products1


Medical condition or history

History of severe allergic reaction (e.g., anaphylaxis) to chicken or egg protein AND currently avoiding exposure to all chicken or egg products1

Discuss risks and benefits with potential recipients. Patient may be vaccinated with a 30-minute observation period following administration.

Alternatively, vaccination may be delayed until an allergist-immunologist is consulted, but the impact of delaying vaccination should be considered.


Suggested action(s)

Discuss risks and benefits with potential recipients. Patient may be vaccinated with a 30-minute observation period following administration.

Alternatively, vaccination may be delayed until an allergist-immunologist is consulted, but the impact of delaying vaccination should be considered.

Moderate or severe acute illness, with or without fever


Medical condition or history

Moderate or severe acute illness, with or without fever

Consider deferring vaccination until the acute illness has improved.


Suggested action(s)

Consider deferring vaccination until the acute illness has improved.

1 JYNNEOS vaccine contains small amounts of gentamicin and ciprofloxacin and is produced using chicken embryo fibroblast cells.

Vaccine providers should be familiar with identifying immediate-type allergic reactions, including anaphylaxis, and be competent in treating these events at the time of vaccine administration. Providers should also have a plan in place to contact emergency medical services immediately in the event of a severe acute vaccine reaction. (ACIP Adverse Reactions Guidelines for Immunization)

CDC’s Clinical Immunization Safety Assessment (CISA) Project is available to provide consultation to U.S. healthcare providers and health departments about complex mpox vaccine safety questions for their patients. See Clinical Immunization Safety Assessment (CISA) Project.

Reporting of Adverse Events

The Vaccine Adverse Event Reporting System (VAERS) is the nation’s early warning system that monitors the safety of vaccines after they are authorized or licensed for use by the U.S. Food and Drug Administration. VAERS accepts and analyzes reports of adverse events following vaccination.

The vaccination provider must report all serious adverse events following administration of JYNNEOS or ACAM2000 vaccine and vaccine administration errors to VAERS.

Per the Emergency Use Authorization

  • Vaccine administration errors, whether or not associated with an adverse event
  • Serious* adverse events (irrespective of attribution to vaccination)
  • Cases of cardiac events, including myocarditis and pericarditis
  • Cases of thromboembolic events and neurovascular events

*Serious adverse events are defined as:

  • Death
  • A life-threatening adverse event
  • Inpatient hospitalization or prolongation of existing hospitalization
  • A persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions
  • A congenital anomaly/birth defect
  • An important medical event that based on appropriate medical judgement may jeopardize the individual and may require medical or surgical intervention to prevent one of the outcomes listed above

Providers are encouraged to also report to VAERS any additional clinically significant adverse events following vaccination, even if they are not sure if vaccination caused the event.

On August 9, 2022, FDA issued an EUA for JYNNEOS mpox vaccine. It authorizes the vaccine to be administered in one of two ways:

  1. Intradermally, between the layers of the skin, preferably on the inner aspect of the forearm, or
  2. Subcutaneously, under the skin, in the upper arm above the elbow.

These are considered routes of vaccination. When submitting a VAERS report, ensure that you document the Route in Section 17 of the VAERS form, by choosing “intradermal” or “subcutaneous” from the selection menu.

For information on how to submit a report to VAERS, visit VAERS—Report an Adverse Event (hhs.gov)

link

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