Animal vaccine trials may not help humans
Vaccine development is challenging in the best of circumstances, and the problems are compounded when we account for government's cumbersome requirements
One only has to get your daily dose of news to feel hopeful about a vaccine to liberate us from the grip of Covid-19. Anchors and reporters lead newscasts with 'promising' and 'encouraging' results from animal tests and human clinical trials.
But is it more hype and hope than anything else? Vaccine development is challenging in the best of circumstances, and the problems are compounded when we account for the federal government's cumbersome requirements and the set of bureaucratic reflexes that slow or misdirect the process.
The pharmaceutical company Moderna says its vaccine stopped the virus from replicating in the lungs of mice, but it didn't highlight that the mice had to be infected with a genetically modified version of the virus because they aren't susceptible to it. The genetic mutation affects the protein that most vaccines, including Moderna's, use to stimulate the immune system, which could very well change the animals' response to infection, rendering the results meaningless.
A vaccine tested in monkeys at the University of Oxford showed that it protected them from pneumonia, but the virus remained in the monkeys' noses. Tests on monkeys at Beth Israel Deaconess Medical Center show that a vaccine produced neutralising antibodies in rhesus macaques. It is unclear how long these antibodies will provide protection against Covid-19 and, more importantly, if it will work in humans.
Another monkey study showed coronavirus infection in rhesus macaques induced effective immune responses against Covid-19. But even the authors hedged their bets, noting "important differences between SARS-CoV-2 infection in macaques and humans, with many parameters still yet to be defined in both species." They urged that "our data should be interpreted cautiously."
One scientist prophetically noted, "mice lie and monkeys exaggerate." For years, a growing number of top scientists have sounded the alarm that animal studies often send us in the wrong direction.
"We are so ingrained in trying to cure mice that we forget we are trying to cure humans," said Dr Ronald Davis, a genomics expert at Stanford.
Vaccine development is challenging and time consuming - an average of 10 and up to 50 years. FDA regulations on new drug development will not only slow the development of a Covid-19 vaccine but also send scientists in the wrong direction by requiring them to use archaic animal-testing protocols.
Animal data is notoriously unreliable for predicting human safety and efficacy, yet animal data is required by the FDA. After all, we've cured cancer in mice for decades. When it comes to HIV, vaccine investigations in chimps showed great promise, but it didn't translate to humans. While scientists have developed life-saving treatments for HIV, there still is no vaccine for HIV/AIDS. There are no vaccines for SARS or MERS.
Given the Covid-19 crisis, and the urgent need for a vaccine to protect the lives of our citizens and to get the economy moving again, it is time for us to revamp drug development strategies and focus them on helping patients by tending to human biology. Human-relevant, cell-based assays, organs-on-a-chip, human-on-a-chip models and sophisticated computer modeling have been developed to more accurately predict human response to new drugs, yet the FDA officially does not acknowledge these superior models in their regulations, requiring drug sponsors to use inferior animal models before the best methods are revved up.
"We don't really need any more data from animal trials to continue," according to a co-leader of one of the monkey studies at Oxford University. "If we get human efficacy, we've got human efficacy, and that's what matters."
If these astute observers are right, and the government doesn't fix this broken system, you may have to stick with the social distancing game plan not for weeks or months, but for years.
Wayne Pacelle is president of the Center for a Humane Economy. Tamara Drake is director of research and regulatory policy for the Center for Responsible Science.
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