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Aug. 6, 2020 | Thursday
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Dr. Brown: Promising progress on COVID vaccines
File photo.

Dr. William Brown
Special to The Lake Report

There have been encouraging results for two mRNA-based vaccines for COVID-19, the most promising of which is the Oxford vaccine.

Traditionally, vaccine development takes three to five years and employs killed or weakened viruses to prompt the immune system to produce antibodies. For most viral diseases, this approach works, but not well for coronaviruses such as SARs and MERS. That suggests a similar approach to developing a vaccine for COVID-19 won’t work. 

The dilemma is that those who catch this disease, especially the well-young who may experience few if any symptoms, may fail to develop a robust immune response or any detectable immune response at all.

That’s unfortunate, because the most vulnerable – the middle-aged and especially older patients and those of any age with significant comorbid conditions – need a significant herd effect in the community, of the order of 60 to 80 per cent of the population with immunity, to stop the virus in the community from spreading.

We are nowhere near that level of natural protection anywhere in the world now and unlikely to get there without reaching significant herd effect levels – especially in the absence of an effective vaccine. That’s certainly the case for the Old Town in Niagara-on-the-Lake. 

To be effective, a vaccine must provoke a robust immune response capable of protecting the young and especially older people from the virus for at least five or more years, and the longer the better.

Older people need a stronger challenge to the immune system, compared to younger people, if they are to mount an effective and lasting response. This was the case with the shingles vaccines, when earlier vaccines reduced the risk of developing shingles by less than 50 per cent and even that paltry protection didn’t last long. The much more effective Shingrix vaccine protects over 90 per cent of older people from shingles and that protection lasts. 

Compared to previous vaccine programs, this one is unique. First, over 100 vaccines are under development around the world. Second, the pace of development is much faster. Third, many of the strategies employed these days are high-tech. Fourth, and troubling, is the concern that some countries might not share their vaccines with other countries. 

One of the most popular high-tech approaches employs messenger RNA (mRNA) that codes for part of the Spike-protein (S-protein). In the horse race for the first effective vaccine, the leader, the Oxford group, employs the Trojan horse approach: they use a tame virus to insert the engineered mRNA into the body’s cells, which manufacture the S-protein. When expressed on the surface of the body’s cells, it provokes the immune response.

The other mRNA approach forgoes the Trojan horse approach and packages the mRNA with nanoparticles. When they are injected into the body, they accomplish much the same the job as the Oxford group’s vaccine.

The difference is that the latter group just published their results of a phase 1 trial. Here Oxford is well ahead and slated to complete a phase 3 trial with 10,000 subjects in the fall, possibly as early as September. Both vaccines are well ahead of the pack and gearing up for mass production as their trials proceed. 

But as the National Institute of Health's Dr. Anthony Fauci and other experts repeatedly remind us, many vaccines fail. My bet is on the Oxford group, in which case we could have an effective vaccine this fall. That would be great news. 

Added note: Both Russia and China claim they will have a vaccine for distribution in the fall. Both apparently hacked Canadian, U.S. and U.K. sources developing vaccines for COVID-19. Are those two claims linked? 

Dr. William Brown is a professor of neurology at McMaster University and co-founder of the Infohealth series held at the Niagara-on-the-Lake Public Library. 

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