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Friday, December 9, 2022
COVID-19: Dr. Brown: Anti-viral drugs could be the answer

Dr. William Brown

Special to The Lake Report

My article on COVID-19 last week was about the importance of achieving herd immunity in the majority of the population as a means of reducing the risk for the most vulnerable in this pandemic, short of an effective vaccine being widely available.

The article was based on evidence in late May that before the late fall or even early 2021 no country would achieve a level of immunity in the population sufficient to prevent a major wave of new infections and deaths associated with reopening.

That meant that the growing pressure to reopen businesses and avoid lasting permanent damage to the world’s economies and jobs is, and will be, at odds with the very measures such as isolation and social distancing that have been so effective in flattening the curve and saving the lives of those most at risk for serious infections and death from COVID-19. 

Of course, those gloomy projections about herd immunity could be wrong. Perhaps the percentage of the population who have acquired natural immunity to COVID-19 is much higher than the 20 per cent or less reported for most countries and much closer to the 80 or 90 per cent the “experts” suggest might be necessary to achieve herd immunity.

And maybe the latter figures for effective herd immunity are set too high for COVID-19. Maybe.

And goodness knows, if we’ve learned anything so far in this pandemic, it’s that the experts, the disease modellers and the tests for immunity currently available can all be off-base. But, as matters stand, they’re the best evidence we have and based on that evidence, we badly need effective vaccines in the next few months. 

Fortunately, there’s another option for attacking COVID-19 beyond vaccination – what about antiviral drugs? For some viral diseases, antiviral drugs can be lifesaving, such as Ebola – a far more lethal viral disease than COVID-19. Just as there are now over 100 companies developing vaccines, many companies are rushing to develop an effective antiviral drug – effective enough to prevent the serious complications of COVID-19. 

There are two options: repurpose antiviral drugs used for other viral diseases such as the AIDS virus or Ebola, to name two considered for treatment of COVID-19. Or, what about developing novel new antiviral drugs tailor-made to target specific COVID-19 proteins?

The latter include proteins in the virus’s spike that target the ACE-2 receptors imbedded in a cell’s membrane, the viral proteins responsible for replicating the virus’s genome, others that cut the virus’s proteins at just the right place and yet others that co-opt the cell’s own protein-making machinery. All would make excellent targets for prospective antiviral drugs. 

Not so long ago, any of those jobs would have been a major undertaking lasting many months – certainly well beyond the time frame of this pandemic. Not so this time around.

These days it’s possible, with the aid of high-tech methods coupled with powerful computers, to create 3-D images of key COVID-19 proteins in the virus’s spikes or once inside the cell, created by the virus’s RNA.

Knowing the precise molecular structure and shape of those proteins makes it possible to design drugs that can latch on to targeted proteins by precisely matching the latter’s shape and blocking their function or destroying the viral protein.

But there’s more – virtual simulations make it possible to see whether the fit between candidate drugs and the targeted viral protein is precise enough to warrant clinical trials.

It’s a whole new way of designing and selecting drugs based on matching candidate drugs to detailed molecular models of the targeted protein – and a whole lot quicker than previous methods. There’s even hope that drugs could be designed to target key protein components of all coronaviruses, which could be used to treat variants that might arise in the future through mutations to the virus’s genome. That would be a huge bonus. 

So, it wouldn’t surprise me to learn that we might have several effective new antiviral drugs and, with luck, several effective vaccines before the year is out. And, hopefully, we will also have much more reliable blood tests to identify the immune status of everyone who works in high-risk care facilities such as long-term care and hospitals.

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