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Testing tuberculosis vaccine combinations for COVID-19

Researchers at the University of Sydney and Centenary Institute are repurposing an existing tuberculosis vaccine to see if it can be used in a new way against COVID-19 to develop a novel vaccine.

The vaccine candidate, which Australian researchers have called BCG:CoVac, combines the vaccine for tuberculosis, Bacille Calmette-Guérin (BCG) with major components of the SARS-CoV-2 virus. The SARS-CoV-2 virus is the pathogen that causes the COVID-19 disease.

The study is part of a collaboration between the University of Sydney and the Centenary Institute to examine the immune response created by new vaccine candidates, including BCG:CoVac.

Lead investigator Professor Jamie Triccas, from the School of Medical Sciences, Faculty of Medicine and Health, and the Charles Perkins Center said the team was motivated to apply their expertise in studying vaccines to assess the effectiveness of this new formulation.

“We have over two decades of experience in the development and testing of tuberculosis vaccines, which will be applied for the assessment of BCG:CoVac,” said Professor Triccas.

“There have yet to be studies published that combine BCG and components of the SARS-CoV-2 virus as part of a new vaccine design, and we’re excited to test their potential.”

Early results promising

The researchers’ early unpublished results from pre-clinical testing in mice show BCG:CoVac stimulated an immune response aimed to control virus infection in humans.

In mice vaccinated with BCG:CoVac, the vaccine induced high levels of SARS-CoV-2-specific antibodies. The role of these antibodies is to bind the virus and help eliminate it from the body. The vaccine also triggered a strong anti-viral response by T cells (a type of immune cell).

Both these types of immune responses are thought to be important to ensure clearance of the SARS-CoV-2 virus from infected individuals.

Importantly, preliminary data also showed BCG:CoVac did not create high levels of inflammatory responses, which is a common barrier and concern in vaccine design.

“These initial results are very promising. BCG:CoVac is making the type of immune response that we predict is needed to control SARS-CoV-2 infection in humans,” said Professor Triccas.

“We are currently determining how well the antibodies generated after vaccination can ‘block’ the virus from infecting cells and thus provide protection from disease.”

Using the TB vaccine as a vehicle

In BCG:CoVac, the BCG vaccine is used as a vehicle to deliver distinctive proteins that originate from the SARS-CoV-2 virus surface. The goal is for the human immune system to develop a memory of SARS-CoV-2 and develop immunity.

There is currently global interest in the BCG vaccine, which is being investigated in ongoing clinical trials as a possible intervention to protect vulnerable people during the COVID-19 pandemic.

This is because of suggestions the BCG vaccine has other beneficial effects on the immune system that could protect against other infections. A 2019 observational study reported the vaccine is related to fewer deaths from certain infections other than from TB in low-income countries.

However, current COVID-19 related studies only investigate the protective effects of the BCG vaccine by itself.

Dr. Claudio Counoupas, research scientist at the Centenary Institute and co-lead on the project, said: “Combining a part of the SARS-CoV-2 virus with BCG is key to this new vaccine. This provides a specific ‘memory’ immune response against the virus that could provide long-term protection against disease. Our on-going studies will determine how long the immune response lasts after vaccination in animal models. This is important information for future human testing of our vaccine.”

Professor Triccas said animal studies were necessary to ensure the vaccine is inducing the right type of immune response.

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Pfizer reports encouraging, very early vaccine test results

The first of four experimental COVID-19 vaccines being tested by Pfizer and its German partner BioNTech showed encouraging results in very early testing of 45 people, the companies said Wednesday.

Study volunteers given either a low or medium dose, in two shots about a month apart, had immune responses in the range expected to be protective, when compared to some COVID-19 survivors, according to the preliminary results.

Side effects were typical for vaccines, mostly pain at the injection site and fever.

The report has been submitted for publication in a scientific journal but not yet reviewed. With its other potential candidates still in the earliest stage of testing, Pfizer aims to open a large-scale study this summer but can’t yet say which shot is best to include.

But researchers didn’t administer a second shot of the highest dose initially tested, sticking with the low and medium doses. The higher-dose shot caused more injection reactions without apparent added benefit.

About 15 different COVID-19 vaccine candidates are in human testing worldwide, with several poised to begin huge, last-stage studies to prove if they really work.

Different companies are pursuing different types of vaccines, boosting the odds that at least one approach might work—although there’s no guarantee. The Pfizer and BioNTech candidates use a piece of the coronavirus genetic code to prime the body to recognize and attack the virus.

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US biotech firm Inovio reports encouraging virus vaccine results

The US biotech firm Inovio reported preliminary but encouraging results Tuesday from tests of an experimental coronavirus vaccine.

Administered to 40 volunteers, it triggered an immune system response in 94 percent of those who completed the so-called phase one clinical trial, meaning they received two injections, four weeks apart.

Inovio’s vaccine, called INO-4800, is designed to inject DNA into a person so as to set off a specific immune system response against the SARS-CoV-2 virus.

The medication is injected under the skin with a needle, then activated with a device that resembles a toothbrush, which delivers an electrical impulse for a fraction of a second, allowing the DNA to penetrate the body’s cells and carry out its mission.

Inovio, which is financed by the US Defense Department and the NGO CEPI, also said it has been included in President Donald Trump’s plan to produce hundreds of millions of doses of the vaccine by January as part of Operation Warp Speed.

Inovio’s medication is the only DNA vaccine that is stable at room temperature for more than a year and does not need refrigeration for transport or storage for several years, said Inovio CEO Joseph Kim.

This is a big plus when it comes to vaccinating people in developing countries, where it is harder to maintain the cold chain needed to preserve many products.

A total of 23 COVID-19 vaccine projects have launched clinical trials on humans, says the London School of Hygiene & Tropical Medicine, and several have moved to phase two or three, which means they are being injected into thousands or even tens of thousands of volunteers.

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