Prototype Vaccine Protects Monkeys From Coronavirus


A prototype vaccine has protected monkeys from the coronavirus, researchers reported on Wednesday, a finding that offers new hope for effective human vaccines.

Scientists are already testing coronavirus vaccines in people, but the initial trials are designed to determine safety, not how well a vaccine works. The research published Wednesday offers insight into what a vaccine must do to be effective and how to measure that.

“To me, this is convincing that a vaccine is possible,” said Dr. Nelson Michael, the director of the Center for Infectious Diseases Research at Walter Reed Army Institute of Research.

Scientists are engaged in a worldwide scramble to create a vaccine against the new coronavirus. Over a hundred research projects have been launched; early safety trials in humans have been started or completed in nine of them.

Next to come are larger trials to determine whether these candidate vaccines are not just safe, but effective. But those results won’t arrive for months.

In the meantime, Dr. Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston, and his colleagues have started a series of experiments on monkeys to get a broader look at how coronaviruses affect monkeys — and whether vaccines might fight the pathogens. Their report was published in Science.

Dr. Barouch is working in a partnership with Johnson & Johnson, which is developing a coronavirus vaccine that uses a specially modified virus, called Ad26, that he developed.

The new research in monkeys “lays the scientific foundations” for those efforts, Dr. Barouch said. In March, the federal government awarded $450 million to Janssen Pharmaceuticals, a division of Johnson & Johnson, to develop a coronavirus vaccine.

The scientists started by studying whether the monkeys become immune to the virus after getting sick. The team infected nine unvaccinated rhesus macaques with the new coronavirus.

The monkeys developed symptoms that resembled a moderate case of Covid-19, including inflammation in their lungs that led to pneumonia. The monkeys recovered after a few days, and Dr. Barouch and his colleagues found that the animals had begun making antibodies to the coronavirus.

Some of them turned out to be so-called neutralizing antibodies, meaning that they stopped the virus from entering cells and reproducing.

Thirty-five days after inoculating the monkeys, the researchers carried out a “re-challenge,” spraying a second dose of the coronavirus into the noses of the animals.

The monkeys produced a surge of protective neutralizing antibodies. The coronavirus briefly managed to establish a small infection in the monkey’s noses but was soon wiped out.

ImageDr. Dan Barouch, a virologist at Beth Israel Deaconess Medical Center. “This increases our optimism that a vaccine for Covid-19 will be possible,” he said.
Credit…Tony Luong for The New York Times

These results don’t necessarily mean that humans also develop strong, last-lasting immunity to the coronavirus. Still, Dr. Barouch and others found the research encouraging.

“If we did the re-challenge study and it didn’t work, the implication would be that the entire vaccine effort would fail,” he said. “That would have been really, really bad news for seven billion people.”

In a separate experiment, Dr. Barouch and his colleagues tested prototype vaccines on rhesus macaques. Each monkey received pieces of DNA, which their cells turned into viral proteins designed to train the immune system to recognize the virus.

Both macaques and humans make neutralizing antibodies against coronaviruses that target one part in particular: a protein that covers the virus’s surface, called the spike protein.

Most coronavirus vaccines are intended to coax the immune system to make antibodies that latch onto the spike protein and destroy the virus. Dr. Barouch and his colleagues tried out six variations.

The researchers gave each vaccine to four or five monkeys. They let the monkeys develop an immune response for three weeks, and then sprayed viruses in their noses.

Some of the vaccines provided only partial protection. The virus wasn’t entirely eliminated from the animals’ lungs or noses, although levels were lower than in unvaccinated monkeys.

But other vaccines worked better. The one that worked best trained the immune system to recognize and attack the entire spike protein of the coronavirus. In eight monkeys, the researchers couldn’t detect the virus at all.

“I think that overall this will be seen as very good news for the vaccine effort,” said Dr. Barouch. “This increases our optimism that a vaccine for Covid-19 will be possible.”

Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai in New York who was not involved in the study, said that the levels of antibodies seen in the monkeys were promising.

“This is something that would protect you from disease,” he said. “It’s not perfect, but you certainly see protection.”

Two vaccine teams — one at the University of Oxford and one at the China-based company Sinovac — have tested vaccines on rhesus macaques. This month they reported that their vaccines also offered the animals protection.

  • Frequently Asked Questions and Advice

    Updated May 20, 2020

    • How many people have lost their jobs due to coronavirus in the U.S.?

      Over 36 million people have filed for unemployment since March. One in five who were working in February reported losing a job or being furloughed in March or the beginning of April, data from a Federal Reserve survey released on May 14 showed, and that pain was highly concentrated among low earners. Fully 39 percent of former workers living in a household earning $40,000 or less lost work, compared with 13 percent in those making more than $100,000, a Fed official said.

    • Is ‘Covid toe’ a symptom of the disease?

      There is an uptick in people reporting symptoms of chilblains, which are painful red or purple lesions that typically appear in the winter on fingers or toes. The lesions are emerging as yet another symptom of infection with the new coronavirus. Chilblains are caused by inflammation in small blood vessels in reaction to cold or damp conditions, but they are usually common in the coldest winter months. Federal health officials do not include toe lesions in the list of coronavirus symptoms, but some dermatologists are pushing for a change, saying so-called Covid toe should be sufficient grounds for testing.

    • Should I wear a mask?

      The C.D.C. has recommended that all Americans wear cloth masks if they go out in public. This is a shift in federal guidance reflecting new concerns that the coronavirus is being spread by infected people who have no symptoms. Until now, the C.D.C., like the W.H.O., has advised that ordinary people don’t need to wear masks unless they are sick and coughing. Part of the reason was to preserve medical-grade masks for health care workers who desperately need them at a time when they are in continuously short supply. Masks don’t replace hand washing and social distancing.

    • What should I do if I feel sick?

      If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.

    • Should I pull my money from the markets?

      That’s not a good idea. Even if you’re retired, having a balanced portfolio of stocks and bonds so that your money keeps up with inflation, or even grows, makes sense. But retirees may want to think about having enough cash set aside for a year’s worth of living expenses and big payments needed over the next five years.

    • How can I help?

      Charity Navigator, which evaluates charities using a numbers-based system, has a running list of nonprofits working in communities affected by the outbreak. You can give blood through the American Red Cross, and World Central Kitchen has stepped in to distribute meals in major cities.

The new study provides a deeper look at how vaccines protect monkeys, and perhaps one day humans.

Along with neutralizing antibodies, the immune system has a huge arsenal of weapons it can deploy against pathogens. Some immune cells can recognize infected cells and destroy them, for example.

Dr. Barouch and his colleagues found a strong connection between neutralizing antibodies and how well a vaccine worked: The vaccines that gave monkeys stronger protection produced more neutralizing antibodies.

Pamela Bjorkman, a structural biologist at Caltech who was not involved in the study, said that this correlation gave her more confidence in Dr. Barouch’s findings. “I think that’s really reassuring,” she said.

Dr. Michael said that link could help scientists running safety trials in humans. They may be able to get some early clues about whether the vaccines are effective.

When a new vaccine goes into testing, the first round of trials are designed to see if it’s safe. Only then do researchers move forward with bigger trials to determine if the vaccine actually protects against a disease.

Vaccine designers often try different doses in a safety trial, looking for the lowest dose that provides the greatest protection. Dr. Barouch’s study suggests that measuring neutralizing antibodies can give an indication if a dose will be potent enough to give protection.

Malcolm Martin, a virologist at the National Institutes of Health who was not involved in the study, cautioned that monkeys are different from humans in important ways.

The unvaccinated monkeys in this study didn’t develop any of the severe symptoms that some people get following a coronavirus infection. “It looks like they got a cold,” Dr. Martin said.

Lisa Tostanoski, a postdoctoral fellow working with Dr. Barouch and co-author of the new study, noted that the study only offers a glimpse at how the vaccine works three weeks after injection.

It’s possible that the vaccines may defend the monkeys for many years to come, she noted — or the protection may fade much sooner.

How long immunity to the coronavirus lasts may determine whether people will need just one shot of a vaccine or more. People may need boosters from time to time to rev up their defenses again and keep the pandemic at bay.

“Every three years is thinkable,” Dr. Krammer said. “That doesn’t mean a vaccine doesn’t work.”


Please enter your comment!
Please enter your name here