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Tuesday, July 21, 2020, 18:28
Virus: Wave of promising study results raise hopes for vaccines
By Reuters
Tuesday, July 21, 2020, 18:28 By Reuters

In this handout photo released by the University of Oxford, a volunteer participates in the vaccine trial in Oxford, England on July 7, 2020. (PHOTO / UNIVERSITY OF OXFORD VIA AP)

CHICAGO - Early data from trials of three potential COVID-19 vaccines released on Monday, including a closely-watched candidate from Oxford University, increased confidence that a vaccine can train the immune system to recognize and fight the novel coronavirus without serious side effects.

Whether any of these efforts will result in a vaccine capable of protecting billions of people and ending the global pandemic that has claimed more than 600,000 lives is still far from clear. All will require much larger studies to prove they can safely prevent infection or serious disease.

The vaccine being developed by British drugmaker AstraZeneca along with Oxford University, induced an immune response in all study participants who received two doses without any worrisome side effects.

A coronavirus vaccine being developed by British drugmaker AstraZeneca along with Oxford University, and another under development by CanSino Biologics Inc and China's military research unit, as well as one being developed by Moderna Inc all induced an immune response in study participants without serious side effects

A coronavirus vaccine under development by CanSino Biologics Inc and China's military research unit, likewise showed that it appears to be safe and induced an immune response in most of the 508 healthy volunteers who got one dose of the vaccine, researchers reported.

Some 77 percent of study volunteers experienced side effects like fever or injection site pain, but none considered to be serious.

Both the AstraZeneca and CanSino vaccines use a harmless cold virus known as an adenovirus to carry genetic material from the novel coronavirus into the body. Studies on both vaccines were published in the journal The Lancet.

"Overall, the results of both trials are broadly similar and promising," Naor Bar-Zeev and William Moss, two vaccine experts from Johns Hopkins Bloomberg School of Public Health, wrote in a commentary in The Lancet.

However, the CanSino candidate again showed signs that people who had previously been exposed to the particular adenovirus in its vaccine had a reduced immune response.

The study authors called that "the biggest obstacle" for the vaccine to overcome.

ALSO READ: Chinese firm: Vaccine candidate shows promise in human test

German biotech BioNTech and US drugmaker Pfizer Inc released details from a small study in Germany of a different type of vaccine that uses ribonucleic acid (RNA) - a chemical messenger that contains instructions for making proteins.

The vaccine instructs cells to make proteins that mimic the outer surface of the coronavirus. The body recognizes these virus-like proteins as foreign invaders and can then mount an immune response against the actual virus.

In the not-yet peer reviewed study of 60 healthy adults, the vaccine induced virus-neutralizing antibodies in those given two doses, a result in-line with a previous early-stage US trial.

The burst of announcements followed publication last week of results of Moderna Inc's vaccine trial, showing similarly promising early results. Moderna's vaccine also uses a messenger RNA platform.

READ MORE: Moderna coronavirus vaccine shows promise in key early trial

"It's encouraging that all these vaccines seem to induce antibodies in people," said former World Health Organization (WHO) assistant director-general Marie-Paule Kieny of the French research institute Inserm. "This proves that the science is moving forward very quickly, which is a good sign."

'Long way to go'

None of these leading contenders has shown side effects that could sideline their efforts so far, but all must still prove they are safe and effective in trials involving thousands of subjects, including those at high-risk for severe COVID-19, such as the elderly and people with diabetes.

Historically, just 6 percent of vaccine candidates end up making it to market, often after a years-long testing process. Vaccine makers hope to dramatically compress that timeline through faster trials and by manufacturing at scale even before the products prove successful.

The Oxford/AstraZeneca vaccine is one of 150 in development globally, but is considered the most advanced

READ MORE: India's first COVID-19 vaccine races to meet mid-August target

Several manufacturers have US government backing with a goal of having a coronavirus vaccine by year's end as cases continue to rise at a record pace.

The Oxford/AstraZeneca vaccine is one of 150 in development globally, but is considered the most advanced. Late-stage trials have begun in Brazil and South Africa and are due to start in the United States, where the infection prevalence is highest.

The vaccine could be rolled out by the end of the year but there is no certainty that will happen, the lead developer of the vaccine, Sarah Gilbert, said on Tuesday. The Oxford scientists had eyed a million doses of the potential vaccine to be produced by September.

In its Phase I trial, the vaccine induced so-called neutralizing antibodies - the kind that stop the virus from infecting cells - in 91 percent of individuals a month after they got one dose, and in 100 percent of subjects who got a second dose. These levels were on par with the antibodies produced by people who survived COVID-19 - a key benchmark of potential success.

Gilbert said the trial could not determine whether one or two doses would be needed to provide immunity.

The vaccine, known as AZD1222, also induced the body to make T cells - activating a second part of the immune system that experts increasingly believe will be important for a lasting immune response.

Recent studies show that some recovered patients who tested negative for coronavirus antibodies developed T cells in response to their infection. Scientists think both are important aspects of an effective coronavirus vaccine.

Dr Mike Ryan, head of WHO's emergencies program, said the generation of both T-cell and neutralizing antibody responses was positive, adding, "there is a long way to go."

ALSO READ: Spain's virus rate triples in three weeks after lockdown easing


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