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COVID-19: Prototype vaccine protects monkeys from the virus

The published research has offered an insight into what a vaccine must do in order to be effective and how it can be measured.

May 26, 2020 18:07 IST
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Researchers have reported that a prototype vaccine has been protecting monkeys from Coronavirus. The report has offered new hope for the effective vaccine that will work on humans as well.

The published research has offered an insight into what a vaccine must do in order to be effective and how it can be measured. Scientists all over the world have been testing Coronavirus vaccines on people but these initial trials aim at determining the safety and not how well these vaccines will work.

As per Dr. Nelson Michael, Director of the Centre for Infectious Diseases Research at Walter Reed Army Institute of Research, the research has convinced that the vaccine for humans against COVID-19 is possible after all.

Key Highlights:

•  Scientists have been engaged to create a vaccine for the treatment of novel coronavirus. Over a hundred research projects have already been launched and the early trials in humans have been started or completed in nine of them.

•  Next will be the large trials to determine whether the candidate vaccines are not just safe but effective as well but results won’t arrive in months.

•  Dan Barouch, a virologist at Beth Israel Deaconess Centre Medical Centre in Boston along with his colleagues have started on monkeys to get a broader look at how COVID-19 will affect the monkeys and whether the vaccines will be able to fight the pathogens. The report was published in Science.

•  Barouch has been working in partnership with Johnson & Johnson, who has also been developing a COVID-19 vaccine that uses a specially modified virus named Ad26.

•  In March 2020, the federal government had awarded $450 million to Janssen Pharmaceuticals, which is a division of Johnson & Johnson, for developing COVID-19 vaccine.

Research on monkeys for COVID-19 vaccine:

The scientists started their study by researching whether the monkeys can become immune to the virus after getting sick. The team of the scientists infected nice rhesus macaques with coronavirus. These nine monkeys were unvaccinated at that time.

The monkeys started developing symptoms that were similar to a modern case of COVID-19, it included inflammation in their lungs that led to pneumonia. Barouch and his colleagues discovered that monkeys recovered after a few days and that they had started making antibodies to the coronavirus. Some of them also turned out to be so-called neutralizing antibodies which meant that they stopped the virus from entering the cells and reproducing.

After thirty-five days of inoculating the monkeys, the scientists carried out a re-challenge, by spraying a second dose of Coronavirus into the animal’s noses. The monkeys had produced protective neutralizing antibodies. The virus briefly managed to establish a small infection in the animal’s noses but it was soon wiped out.

Even though the results do not mean that humans will also develop strong and long-lasting immunity against COVID-19, Barouch and the other scientists still found the research encouraging.

Barouch mentioned that if the re-challenge was done and it didn’t work, the implication will be that the entire vaccine effort would fail and it would have been the bad news for 7 billion people.

Test of Prototype vaccine on rhesus macaques:

In another experiment, Barouch, and the researchers tested prototype vaccines on rhesus macaques. Under this, each monkey received pieces of DNA, which their cells turned into viral proteins, designed to train the immune system to recognize the virus.

It has been observed that bot macaques and humans make neutralizing antibodies against COVID-19 that target one part in particular: the spike protein, it covers the virus’s surface.

Most of the COVID-19 vaccines have been intended to coax the immune system to make antibodies that latch onto the spike protein and destroy the virus. Barouch and the researchers tried out six variations.

Each vaccine was given to four or five monkeys. The researchers further led the monkeys to develop an immune response for three weeks and then sprayed the virus into the animal's noses.

It was noted that some of the vaccines provided partial protection and the virus was not entirely eliminated from the animals’ noses or lungs. It was observed although the levels were lower than in unvaccinated monkeys.

The one vaccine that worked the best trained the immune system to recognize and attack the entire spike protein of Coronavirus. In eight monkeys, scientists couldn’t detect the virus at all.

Barouch on the results commented that this can be seen as very good news for the vaccine effort and increases the chances that the vaccine for COVID-19 will be possible in the future.

A virologist at the Icahn School of Medicine at Mount Sinai in New York, Florian Krammer, who was not involved in the study stated that the levels of antibodies seen in monkeys were promising. He further added that it is something that will protect you from the virus, it is not perfect but there will be protection.

Research supports other experiments on monkeys for COVID-19 vaccine:

Two vaccine teams- one at China-based company Sinovac and one at the Oxford University- have also tested the vaccines on rhesus macaques. They also reported that their vaccines had also offered protection to the animals.

The new study also provides a deeper look at how vaccines can protect monkeys and maybe one day humans as well. Along with the neutralizing antibodies, the immune systems also had a huge arsenal of weapons that it can deploy against the pathogens.  

Barouch and the researchers found a strong connection between neutralizing antibodies and how well the vaccine will work. The vaccines that gave monkeys stronger protection had produced more neutralizing antibodies.

Pamela Bjorkman from California Institute of Technology, who was not involved in the study also mentioned that the co-relation gave her more confidence in Barouch’s findings.

The link could also help the scientists who are running safety trials on humans and they may be able to get some early clues about whether the vaccine is effective. Vaccine designers have often been trying different doses in safety trials, which is to see if it is safe. They look for the lowest dose that will provide the greatest protection. Barouch’s study will suggest that measuring neutralizing antibodies can indicate if a dose will be potent enough to give protection.

Limitations to the study:

Malcolm Martin from National Institutes of Health, who was not a part of the study had cautioned that monkeys are different from humans in important ways. It must be observed that the unvaccinated monkeys in the study did not develop any of the severe symptoms as same as humans following a coronavirus infection.

Lisa Tostanoski, who was a co-author of the new study and postdoctoral fellow working with Barouch stated that the study has only been offering a glimpse of how the vaccine works three weeks after giving the injection. She noted that it is entirely possible that the vaccine may defend the monkeys for many years to come or maybe the protection may fade sooner.

For how long a time the immunity to coronavirus will last will be able to determine whether people will need one shot of vaccine or more. People may also need boosters from time to time to build up their defenses again to keep the pandemic at bay. As per Kramer, three years is thinkable but that doesn’t mean that vaccine doesn’t work.

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