[D66] Human challenge trials are being pushed to develop a vaccine against the coronavirus

[R.O.]

wsws.org:

Human challenge trials are being pushed to develop a vaccine against the 
coronavirus
By Benjamin Mateus
5 May 2020

Without much fanfare, news reports on vaccines against the coronavirus 
have been focusing on ways to expedite vaccine development through human 
challenge trials. In a nutshell, such trials would deliberately infect 
healthy volunteers with the coronavirus after they received the 
experimental vaccine, to determine its efficacy.

Democratic Representative Bill Foster of Illinois, leading the effort 
with 34 other members of the House of Representatives, sent a letter to 
the Food and Drug Administration, stating, “A more risk-tolerant 
development process is likely appropriate in the case of COVID-19 
vaccine. The enormous human cost of the COVID-19 epidemic alters the 
optimization of the risk/benefit analysis.”

Josh Morrison, a member of a supposed grass-roots effort, 1 Day Sooner, 
told Nature magazine, “We want to recruit as many people as possible who 
want to do this, and pre-qualify them as likely to be able to 
participate in challenge trials would they occur. At the same time, we 
feel that the public policy decisions around challenge trials will be 
better informed if they highlight the voice of people interested in 
participating in such trials.” According to the group, thousands from 
over 50 countries have volunteered.

Vaccine trials are notoriously lengthy, with optimistic estimates of 12 
to 18 months to vaccine rollout. Much of the time in vaccine trials is 
spent in testing the safety and efficacy of a vaccine. These 
placebo-controlled phase-three trials, in which one group receives the 
vaccine and another a placebo, typically involve several thousands of 
participants who are followed long enough to assess differences in 
disease incidence.

Human challenge trials have been conducted over hundreds of years but 
are trials of last resort and conducted under special circumstances and 
much oversight. In the case of COVID-19, they were first raised in late 
March in a proposal published in the Journal of Infectious Diseases by 
authors Nir Eyal, Marc Lipstich, and Peter G. Smith. They wrote in their 
abstract, “By replacing conventional phase-three testing of vaccine 
candidates [with human challenge trials], such trials may subtract 
months from the licensure process, making efficacious vaccines available 
more quickly.”

The role of vaccines in global health cannot be understated. Smallpox 
was eradicated in 1977, the last case occurring in Somalia. Polio was 
eliminated in the United States in 1979. After a global campaign 
launched in 1994 by the United Nations Food and Agriculture 
Organization, rinderpest, a viral infection of cattle and domestic 
buffalo with near 100 percent lethality to livestock, was last confirmed 
in 2001 and declared eradicated in June 2011.

Measles, a virus for which only humans act as a host, killed 7 million 
to 8 million children annually until a decade of work led eventually to 
the development of a vaccine in 1963. Still, and despite an effective 
vaccine being available, measles infects more than half a million people 
across the globe, killing more than 140,000 people annually, mostly 
children under five years of age. Countries with the highest incidence 
include the Democratic Republic of Congo, Liberia, Madagascar, Somalia, 
and Ukraine—these five account for almost half of all cases worldwide.

The vaccination program in the United States, according to the CDC, has 
prevented more than 21 million hospitalizations and 732,000 deaths among 
children born in the last 20 years. Besides the morbidity and mortality 
associated with vaccinations, the economic benefits translate to $295 
billion in direct costs and $1.38 trillion in total societal costs.

Efforts have been underway to develop a vaccine against the SARS-CoV-2 
virus. Many see a vaccine as the only solution to the pandemic. With no 
pharmaceutical treatments that have shown clear mortality benefits, the 
present public health measures and supportive medical care remain 
essentially the only means by which to address the coronavirus and its 
impact on human populations.

According to the World Health Organization (WHO), there are currently 
six human trials in the race to develop a vaccine against SARS-CoV-2. 
Moderna, working in association with the NIAID, and INOVIO 
Pharmaceuticals are US-based trials, both in phase I. Moderna was the 
first to begin testing on humans in mid-March, building on its previous 
work on other coronaviruses. The University of Oxford, in Britain, is in 
phase I/II trial using a nonreplicating viral vector. The study is being 
led by Dr. Sarah Gilbert, who previously led work on “Disease X,” a 
hypothetical pathogen with pandemic potential adopted by the WHO on 
their shortlist of blueprint priority diseases. The other three trials 
are from China—CANSINO Biological, SINOVAC, and Beijing Institute of 
Biological Products. Seventy-seven other trials are in the preclinical 
evaluation stage.

In October 2016, the World Health Organization issued a statement on 
regulatory considerations for vaccine trials that pursue human challenge 
trials to expedite the development of these critical preventative 
treatments. They write, “It is essential that challenge studies be 
conducted within an ethical framework in which truly informed consent is 
given. When conducted, human challenge studies should be undertaken with 
abundant forethought, caution, and oversight. The information to be 
gained should clearly justify the risks to human subjects.”

The WHO notes that if a pathogen has a high case fatality rate and there 
are no existing therapies to prevent or diminish the impact of the 
disease and preclude death, then it would not be appropriate to consider 
such trials. Based on reports, they are planning to publish a response 
to proposed COVID-19 human challenge trials soon.

Authors Eyal et al., in regard to concerns about a human challenge trial 
for COVID-19, admit that it could be possible that any protection 
demonstrated from a vaccine in a human challenge study may not be 
replicated when the vaccine is used in the population at large.

Additionally, there is no attenuated SARS-CoV-2 virus that can help 
participants avoid the hazards associated with COVID-19, as was 
indicated in the WHO’s guidance, nor is there a therapeutic that could 
safely reduce the mortality risk after the participants are infected. 
More concerning, they write, is that “some vaccine constructs against 
coronavirus may induce more severe disease following infection, as has 
been reported in animal models of both SARS and MERS vaccine 
candidates.” For this reason, they recommend challenging small groups 
sequentially to address this issue.

In support of the proposal, they state that these volunteers will have 
voluntarily consented to take these risks. They write, “In the present 
case, the study would involve multiple tests of comprehension of all 
risks so that the decision is deeply informed and voluntary.” These 
participants would be isolated in treatment facilities and given the 
best care possible.

They also justified the conduct of the trial on the grounds that 1) the 
study will only recruit healthy participants, 2) the vaccine likely will 
benefit some of those in the trial, 3) in the absence of a vaccine they 
are likely to be infected anyway, 4) only people with a high baseline 
risk of getting exposed should be recruited, 5) participants would be 
afforded the best available care, and 6) potentially some therapeutics 
may be available to ameliorate morbidity or mortality.

Dr. Beth Kirkpatrick, professor and chair of the Department of 
Microbiology and Molecular Genetics at the University of Vermont, who 
runs a human challenge trial unit, explained to STAT that human 
challenge models for COVID-19 do not exist. She said it would take 
upwards of two years to design and approve one, given all the ethical 
and regulatory constraints that they entail.

One of the primary considerations with such a human challenge trial is 
to establish appropriate endpoints for symptoms—flu-like illness or 
pneumonia—and their implications for the efficacy of the vaccine. As 
yet, scientists are still puzzled over why some people become ill while 
others do not, and why symptomatic patients have a constellation of 
symptoms as compared to others. Additional concerns raised include if 
the data from such a study will translate to efficacy in all age 
categories, since the population being tested is young and healthy. 
Information about vaccine safety would also be compromised in these 
smaller trials.

The working class must treat with a great deal of skepticism the claimed 
benefits of such treatments and how such studies are being conducted, 
especially in the face of a pandemic with a novel coronavirus that at 
every turn has surprised and baffled scientists and researchers. Given 
the despair and upheavals caused by this pandemic, volunteers for these 
trials will likely come from among workers who are at the highest risk 
for contracting the infection because of the “essential” nature of their 
work.

That these human challenge trials are being vigorously supported by the 
political establishment is deeply concerning. The normal sentiments of 
mistrust, caution, and vigilance to protect the individuals involved 
seem absent. Ultimately, the race for vaccine development is rooted in 
capitalist relations which provide a tremendous profit incentive to the 
corporations that manufacture them, in addition to the general concern 
in ruling circles about promoting a back-to-work policy. The human 
challenge trials become a facilitator for both purposes.

The attempt to cut corners and expedite trials have already led to 
abject failures, which in the long run only delay the need to determine 
which therapeutics and vaccines will work and are inherently safe and 
which present adverse profiles. In the face of the frenzy and despair 
that is igniting social tensions, it becomes even more necessary to 
adhere rigorously to scientific principles. Even in desperate times, 
these principles will save time, life, and resources.