Advice letter: Michael Driver, Member of the Board of Improvement Finance, Liverpool City Council

JCI statement on vaccine dose prioritization in response to the monkeypox outbreak

background

In May 2022, ongoing transmission of monkeypox virus was identified in the United Kingdom. This outbreak differs from previous monkeypox outbreaks in the United Kingdom in that cases were either imported from monkeypox-endemic countries (mostly countries in West and Central Africa) or had documented epidemiological links to imported cases, without community transmission.

Monkeypox is a rare disease caused by the monkeypox virus associated with the viruses that cause smallpox and cowpox. Transmission may occur when an individual is in close contact with an animal or human who has previously been infected with monkeypox virus. It may also occur indirectly, for example when a person is in close contact with material contaminated with the virus.

In the current outbreak, cases have been identified primarily among gay, bisexual and other men who have sex with men (GBMSM) Without a history of travel to endemic countries. Epidemiological data indicate that transmission was occurring through direct person-to-person contact in specific sexual networks GBMSM Since at least April 2022. While most cases are in Londoners, cases have been identified in every region of the UK.

In September 2022, modified smallpox vaccine Ankara-North Bavarian vaccine (MVA-BN(by the Medicines and Health Care Products Regulatory Agency)MHRA) for immunization against monkeypox. This vaccine was used in the UK to support the fight against a previous monkeypox outbreak. This vaccine is distributed under the brand names Imvanex (Approved by MHRA in the UK and the European Medicines Agency in Europe for the prevention of smallpox and monkeys) and JYNNEOS (approved in the US for the prevention of smallpox and monkeys).

UK Health Security Agency (UKHSA) working closely with JCVI On the role of vaccination in preventing more cases and reducing ongoing transmission.

Previous tips from JCVI

In May 2022, JCVI They met to discuss and advise on monkeypox vaccination in the context of the ongoing outbreak. UKHSA consult with JCVI They published the Indicative Monkeypox Vaccination Strategy Statement in June 2022 based on the advice given. initial JCVI The advice was formed based on the observed epidemiology and the expected vaccine supply at the time.

The overall goal of the recommended strategy is to interrupt transmission among those at increased risk of monkeypox. The JCVI Also strongly supported the purchase of more potions MVA-BN where possible.

Recommended vaccination before exposure in GBMSM who may be at greater risk of exposure to monkeypox and as an occupational vaccination for workers at high risk of exposure. Those identified in the groups eligible for pre-exposure vaccination are:

  • GBMSM Most at risk were identified by sexual health services using high-risk behavior markers similar to those used to assess eligibility for pre-exposure prophylaxis (PrEP), but applied regardless of HIV status. These risk criteria include:

    • A recent history of multiple partners
    • Participation in group sex
    • Presence of sex venues in the workplace
    • A surrogate sign such as a bacterial sexually transmitted infection (STI) within the past year
  • Occupational vaccination:
    • Staff are expected to provide care for cases of monkeypox in high-consequence infectious diseases (HCIDunits
    • Staff in sexual health clinics assigned to assess suspected cases
    • Employees in additional hospitals abroad HCID Units for the care of monkeypox patients
    • Workers in specialized laboratories where smallpox viruses (such as monkeypox or genetically modified vaccines) are handled, and others who work in specialized and reference laboratories with specific exposure risks according to ACDP guidelines
    • Staff regularly decontaminate the environment around monkeypox cases, even if they are wearing full personal protective equipment

Other health care personnel should be able to avoid unintended exposure by ensuring that suspected monkeypox cases are evaluated by designated personnel, or by wearing appropriate personal protective equipment.

Due to the limited global supply of vaccines, it has been recommended that priority be given to the first doses during this outbreak, with a second dose being offered to those who remain at increased risk of exposure.

Due to the very limited evidence of efficacy when the vaccine is administered post-exposure, it is recommended that the vaccine be administered to close contacts of the cases ideally within 4 days of exposure, up to 14 days in those at risk of developing monkeypox complications.

In August 2022, the United States Food and Drug Administration (FDA) issued Emergency use authorization for emergency use of JYNNEOS for effective monkeypox immunization by intradermal injection.

Intradermal injection uses 0.1 mL of the vaccine and has been shown to be not immunologically inferior to the standard 0.5 mL subcutaneous dose. The European Medicines Agency’s emergency task force has issued a statement that concludes Intradermal use MVA-BN Vaccine was acceptable given the state of the outbreak and significant vaccine shortages.

The JCVI This approach was approved to maximize the number of doses that can be administered without compromising immunity. As a result of this validation, UKHSA Update their recommendations for the use of vaccination before and after exposure during a monkeypox incident.

Updated tip, September 2022

The JCVI It was asked to consider how to allocate these remaining doses due for delivery in August and September 2022, including whether priority should be given to vaccinating the most at-risk group with second doses or whether the priority is to expand eligible groups for first doses.

Early comments from the intradermal administration experience indicate that 4 doses can be obtained from each vial, and that not all clinics will be able to offer intradermal vaccination. The widespread introduction of intradermal vaccination is expected to triple the number of people who can be given the vaccine.

Downstream MVA-BN Vaccine supply, it is believed that a large-scale intradermal introduction of vaccination would allow either the high-risk groups to be vaccinated with two doses, or expand eligibility to include those at lower risk, but with a single dose. However, it is unlikely that there will be sufficient doses to vaccinate all people at lower risk of exposure.

UKHSA A modeling exercise was carried out to estimate the effect of prioritizing immunization of the highest-risk group with two doses, compared to prioritizing expansion of vaccination with a single dose to a wider group.

This modeling indicates that the choice of vaccination strategy (offering second doses to those most at risk, compared to providing single doses for a broader risk group) does not make a significant difference in the size and duration of the outbreak. Providing second doses to the current eligible high-risk group complements their primary pathway, thus increasing both direct and indirect protection through their contribution to current and future transmission.

In addition, this approach may be more operationally feasible as this group has established links with sexual health services and can be identified using existing qualified agents. This approach could potentially leave some doses of the vaccine available for use in outbreaks. Offering vaccination more widely to those at moderate risk of exposure could help prevent further transmission. However, clear criteria for ‘intermediate risk’ should be considered if epidemiology necessitates expanded vaccination coverage.

The JCVI supports UKHSAA proposal to give priority to offering two doses to those in the current target groups for immunization before exposure (GBMSM At highest risk, occupational inoculation) including efforts to maximize uptake of a single dose within this group through participatory activities. People most at risk of exposure should expect to be given two doses of the vaccine.

It is estimated that with plans to roll out intradermal vaccination, there should be more doses than required for the given group. Therefore, once two doses of the vaccine have been offered to those identified as being at high risk and absorption regression, it may be reasonable to offer a single dose to those deemed to be at ‘intermediate’ risk of exposure to help increase resilience against further transmission.

The JCVI Understands the cost implications and impact on delivery capacity that may have to recommend supply expansion. Given the marginal difference between different vaccination strategies, the timing and feasibility of this broader presentation should be considered based on the evolution of epidemiology.

The JCVI It will continue to review the ongoing outbreak and issue updated advice if necessary.

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