High Income Countries Cast Wide Net In Monkeypox Vaccination – As Researchers Scramble for Real-Life Data on Efficacy 
Administering monkeypox vaccine in the United States after HHS deploys 1.1 milion doses.

High income countries like the United States and Canada are casting a wide net in their vaccine strategy for monkeypox, vaccinating people exposed to an infected case and groups at risk of exposure while scrambling to study the results in terms of efficacy. 

That was the upshot of a WHO-sponsored symposium on monkeypox research involving some 40 panelists and over 1,100 participants from around the world that coincided with the closing day of the 24th International AIDS Conference.

Canadian health authorities, for instance, authorized a single monkeypox vaccine dose for people with “high risk exposures to a probable or confirmed case of monkeypox, or within a setting where transmission is happening,” said Matthew Tunis, a researcher with Canada’s Public Health Agency. “If after 28 days, if an individual is assessed as having a predictable, ongoing risk of exposure, a second dose may be offered.”

Tunis said the vaccine also may be offered to special populations, including people who are immunosuppressed, pregnant, breastfeeding, under 18 years of age or have atopic dermatitis. “So the overall gist of the main recommendations are really focused on pre-exposure prophylaxis,” he added, comparing Canada’s approach to that of the United States.

Canada and US take similar approach

Like Canada, the United States emphasizes a prophylactic approach to vaccination. Last Friday it authorized the release of more than 1.1 million vaccine doses, effectively most of what is believed to be in its strategic stockpile.

We have a strategy to deploy these additional vaccine doses in a way that protects those at risk and limits the spread of the virus, while also working with states to ensure equitable and fair distribution,” US Health and Human Services Secretary Xavier Becerra said last Friday in a statement that specifies the distribution plan accounts for the total population of at-risk people and the number of new cases in each jurisdiction.

WHO stresses vaccine ‘equity’  – unclear how that will be achieved

Monkeypox cases and distribution in global mapping led by Oxford and Harvard Universities

WHO officials at the research meeting, meanwhile, stressed that equity must be part of studies into how the vaccine is used and how effective it is. “Equity should be an underlying focus of our efforts,” said Ana Maria Henao Restrepo, a senior WHO scientist.

However, with preemptive campaigns being carried out among those at risk, it remains even more uncertain how far limited monkeypox vaccine supplies can really extend beyond countries that have bought or stockpiled doses recently.   

WHO’s Ana Maria Henao-Restrepo: equity an underlying concern.

Worldwide, there are only about 16.4 million doses of the approved vaccine, MVA-BN, produced by the Danish firm Bavarian Nordic.  Most of those are in bulk form, still requiring a final step of “fill and finish.” The United States already has or has contracted to receive 14.4 million doses, leaving the rest for Canada, the United Kingdom and a handful of other European countries. 

And yet based on last week’s reported cases, then at 17,000, u

However, up to 10 million doses would be needed for a preventive campaign aimed at all high-risk groups in the 77 countries that reported cases, WHO’s Tim Nguyen estimated based on last week’s 17,000 reported cases. That figure has already swelled to 24,406 reported cases, with the US, Spain, Germany and the United Kingdom reporting the highest case loads. 

Meanwhile, the shuttering of Bavarian Nordic’s main manufacturing plant until late 2022 highlights the constraints to global supplies, meaning that outside of a few rich countries, other nations seeing significant cases may not have the option of vaccinating high-risk groups for some time to come. See more here: 

Exclusive: Closure of World’s Only Manufacturing Plant for Monkeypox Vaccine Raises Questions About World’s Ability to Meet Rising Demand

Research questions: one vaccine dose versus 2 and real-life efficacy 

Researchers at the symposium expressed hopes that a few other vaccines now in early or late-stage R&D could eventually be approved for monkeypox. Those could range from KM Biologics‘  smallpox vaccine to a potential mRNA vaccine for monkeypox, which Moderna recently said it is exploring at a “preclinical level.”

At the same time, researchers underlined that critical questions still need to be answered about the efficacy of the approved MVA-BN vaccine in people getting the jab.

The vaccine has mainly been tested on non-human primates such as monkeys, leaving big questions over how it will perform in a variety of real-life settings, including people already exposed and those at potential risk, and in cases such as those involving an infected person’s bedding or closed, confined office spaces or sexual contacts.

Additionally, there are questions over whether a single jab may be sufficient for certain risk groups or with virus variants. 

Experts say these issues will only be resolved following further studies, including some already underway in areas with high caseloads in the US, UK and Spain.  

They agreed, however, that the search for answers must occur in tandem with the rapid deployment of the already approved MVA-BN vaccine in light of the global health emergency recently declared by the World Health Organization

Randomized trials problematic

The urgency of vaccine deployment is already influencing the design of studies, many of which are “retrospective” or “observational studies” of people or groups who received the vaccine or are getting it now. This is in contrast to the “randomized controlled trials” (RCTs) that involve the deliberate administration of a vaccine and placebo to different groups of people at risk, which is typically the gold standard for research trials.

In terms of RCTs, selectively administering placebos to some high-risk groups would likely be both unethical and impractical in terms of attempts to control the new health emergency, experts pointed out.

For instance, in major Canadian cities like Toronto and Montreal, at-risk individuals registered with primary care or sexual health clinics have been invited to get vaccinated, according to Tunis. Singling out some of those people to receive the real vaccine while others get a placebo isn’t really in the cards, he said.

“I don’t think that the randomization of a list approach would really be feasible. It’s been much more driven at the at the community level,” said Tunis.

Speed and agility coupled with validity

Professor John Danesh, Cambridge University

WHO’s Restrepo said what’s needed is a portfolio of randomized and observational evaluations to complement a database that the world can rally around, and the UN health agency wil work with its members to use existing and new vaccines against monkeypox within the framework of clinical efficacy research.

“We are committed to doing so in a way that does not prevent the deployment of such vaccines but in parallel with the deployment of such vaccines,” she said.  

John Danesh of Cambridge University said the evaluation needs to be specific. “We shouldn’t slow down the action, but speed and agility has to be coupled with validity and robustness so that the action has an enduring effect,” he said. Most of the evaluation during the symposium was oriented towards high income countries, he said, but in sub-Saharan Africa it “requires a somewhat different approach.” 

Monkeypox infection has spread globally mainly through communities of men that have sex with men. In central and western African countries where the disease is endemic, however, the infection has traditionally been transmitted to people through contact with infected animals who then might pass it to other household members before it burns itself out. 

In central Africa, the prevailing virus variant, Clade 1, is particularly deadly, with up to a 10% mortality rate. That reflects the importance of prioritizing monkeypox vaccination there, as well, for what has long been a neglected disease.

In those countries, Danesh noted, researchers had pointed to the potential benefits of a “ring vaccination approach” similar to that used with Ebola. That approach prioritizes vaccinating health workers and family contacts of an infected case. 

But as new African countries report monkeypox cases – mostly the milder, West African virus variant, Clade 2, that has been circulating globally – Africa could be experiencing patterns of transmission between men who have sex with men, similar to those globally, along with traditional modes of transmission.

Image Credits: The Hill/Twitter , Global Health Map .

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