Desperation for a way to keep economies from collapsing under the weight of Covid-19 could mean settling for a vaccine that prevents people from getting really sick or dying but doesn’t stop them from catching the coronavirus.
Although a knock-out blow against the virus is the ultimate goal, early vaccines may come with limitations on what they can deliver, according to Robin Shattock, an
“Is that protection against infection?” Shattock said. “Is it protection against illness? Is it protection against severe disease? It’s quite possible a vaccine that only protects against severe disease would be very useful.”
As countries emerge warily from lockdowns, leaders are looking to a preventive shot as the route to return to pre-pandemic life. Fueled by billions of dollars in government investment, vaccines from little-known companies like China’s
At least one of the fastest-moving experimental shots has already advanced into human trials after showing an impact on severe disease -- but less so on infection -- in animals. Experts say such a product would probably be widely used if approved, even if that’s as much as it contributes, until a more effective version comes to market.
“Vaccines need to protect against disease, not necessarily infection,” said
There are drawbacks, though. While holding the potential to save lives, such vaccines might lead to complacency in lockdown-weary nations, said
“My guess would be that the day after someone gets immunized, they’re going to think, ‘I can go back to normal. Everything will be fine,’” he said. “They’re not going to necessarily realize that they might still be susceptible to infection.”
Covid-19 is already thought to be spread by people without symptoms, and a symptom-preventing vaccine may create even greater numbers of them.
Vaccines are among the most effective weapons against infectious disease, and prevent up to 3 million deaths a year, according to the
In their attempts to confront a rapidly growing threat, developers are turning to technologies that have never been used successfully in humans. More than 130 shots are in the works for Covid-19 prevention, according to the World Health Organization.
Vaccines work by presenting the immune system with a form of a germ -- or a key part of it -- preparing the body to respond when a real exposure occurs. When that happens, immune proteins called antibodies glom onto the virus, halting its entry to cells. Sometimes vaccines ramp up immune T-cells, which don’t do as much to prevent infections, but can slow and eventually stop their progression.
A common approach to raising levels of antibodies is with injection of a virus that’s been inactivated or killed. About nine of these are in experimentation: One, made by China’s Sinovac Biotech Ltd., led to high levels of Covid-targeted antibodies in monkeys.
Another shot developed at the
About a quarter of the experimental shots listed by the WHO, including two already in human studies, follow the same approach as the Oxford vaccine. One of the advantages of the technology is its speed. AstraZeneca, which is partnering with Oxford, has said it will begin delivering doses for the U.K. as soon as September, and will have doses for the U.S., which helped fund development, the following month.
On Saturday, AstraZeneca and four European Union countries said they reached an
How the shot being developed by Oxford and AstraZeneca affects infections and infectiousness still isn’t clear.
However, clinical signs of severe infection, like high breathing rate and pneumonia, were better in vaccinated monkeys. That might still make such a shot useful, according to
“That vaccine doesn’t look like it’s a knockout for protecting against infection, but it might be really very good at protecting against disease,” Fauci
The vaccine will be a success whether it heads off infections or severe symptoms, AstraZeneca Chief Executive Officer
Fauci’s NIAID is partnered with
Successful preventives must also bar onward transmission, said Dan Barouch, a researcher at the Center for Virology and Vaccine Research at
“We would potentially consider an indication related to prevention of severe disease, provided available data support the benefits of vaccination,” FDA spokesman Michael Felberbaum said in response to questions. “For licensure we would not require that a vaccine protect against infection.”
Licensed vaccines including some against whooping cough have not been demonstrated to protect against infection with the pathogen that causes the disease but have been demonstrated to protect against symptomatic disease, Felberbaum said.
The notion of using imperfect vaccines and therapies is “fine,” Kinch said. “That’s just practicality. And we may follow those up with more-perfect. There will never be a truly perfect vaccine.”
(Updates with Sinovac testing news in pagraph preceding Antibody Levels subhed. An earlier version of this story corrected researcher’s first name in paragraph before final subhead.)
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