Ask the Pharmacist

Q) I have been hearing lots of news briefs about vaccine developments. What’s the latest information on them?

A) As Canada seems to be experiencing a sudden increase in our daily coronavirus counts once again, it is becoming more and more apparent that the restriction on our activities and public mask donning will be with us until one of two things happens.

The first would be the achievement of herd immunity, the medical term we use to describe that point in time when such a large percentage of the population (the so-called “herd”) has become immune to a disease (in this case as a result of having been previously infected and subsequently having our bodies produce protective antibodies which fight off the virus) making the spread of the disease from person to person unlikely. Herd immunity allows the whole population to be protected, not just those who are already immune.

We have already essentially achieved this with numerous other viruses which once were the scourge of our society such as small pox, polio and at one point measles. The growing number of well-intentioned but misinformed anti-vaxxers have disrupted our herd immunity we once had with measles as there is an increase in this once nearly eradicated disease.

The problem with relying on this for COVID-19 is that most experts estimate that to achieve herd immunity without a vaccine, approximately 70% of the population would first have to get infected. This would also entail all of the deaths and long-term complications (see last week’s article for more on that topic).

As of July 22nd, we have had 112,240 confirmed cases thus far. Canada’s population is estimated to be about 37.75 million people meaning that… (after some sadly needed computer aided division) currently 0.297% of our population has hopefully achieved immunity through this method. Even accounting for all of those who have been infected but never got tested, we are a long, long way from easing our restrictions via this method. In fact, a study released just last week that sampled 10,000 anonymous blood donors in Canada gave us our best indication yet of just how many Canadians have had the disease up to now and they came up with an answer that was just shy of 1% of the population. There are also legitimate concerns about how long and how effective our “natural” immunity is as there are now possible reports of patients becoming infected a second time or not exhibiting antibodies shortly after a positive test.

All of this means that if herd immunity is to be the saviour of our mobile and flexible lifestyles, we have only just begun the journey.

This brings us to our second hope; the development of an effective and safe vaccine. Currently, there are more than 150 possible vaccines in various stages of development aimed at preventing COVID-19 infections. Three in particular are drawing widespread press coverage as results from early clinical trials have been released for public comment. All three are being developed by “big-hitters” in the pharmaceutical industry with names such as AstraZenica (in collaboration with Oxford university), China’s CanSino Biologics and Pfizer (along with the biotech firm BioNTech) being at the forefront.

The Oxford and CanSino teams use a similar technology which takes a modified and, therefore, harmless version of a different virus (this is called a viral vector and it is both the present and future of many medical interventions other than this) to deliver some genetic material from COVID-19 into our cells which subsequently generate an immune response (in the form of antibodies and other infection fighters).

The Pfizer vaccine relies on a different mechanism to introduce the novel coronavirus to our cells, namely ribonucleic acid (the dreaded RNA from your grade 12 biology course). RNA, in a nutshell, is the chemical messenger that contains the instructions that tells our cells to produce proteins. These proteins that are produced as a result of the vaccine resemble the proteins of COVID-19, which once again triggers our body to produce an immune response so that it is ready if and when the real virus shows up. Interestingly, if successful, the Pfizer vaccine will be the first approved messenger RNA vaccine ever despite the fact that the technology has been around for some time.

However, enough of the “sciency” talk and now to discuss the results. With the two viral vector vaccines, the trials were designed mainly to test for safety and hopefully provide hints of their potential effectiveness. Both passed these limited milestones with flying colours producing positive immune responses in recipients according to blood tests without causing dangerous side effects (unless you consider a sore arm and mild fever to fall into that particular category). The Pfizer study was even smaller (60 individuals) but its results were similar to its rivals. As a result of these initial results, further clinical trials are already under way.

AstraZenica has begun late-stage trials in the U.K., Brazil and South America, CanSino has yet to start large-scale trials but apparently the vaccine has already been approved for use in China’s military and Pfizer expects to begin a trial later this month with up to 30,000 participants. All of this is really positive news and has come at an unprecedented speed in terms of traditional vaccine development lifecycles.

However, there are still lots of questions we need to answer beyond the big two; Does it actually help prevent infections and deaths (rather than just producing positive looking blood tests) and is it safe when used among the general population (as opposed to early clinical trials which tend to be populated by young, healthy and predominantly male individuals who need a few bucks in their pockets and whom are far less likely to suffer from side effects than the rest of us.)?

Some of these questions include:

  • how long will the immune response last. Will it be like the pneumonia shot (Prevnar or Pneumovax) where one dose does you for life or will it be like the flu shot which is annual or might it only help us for a few months at best?
  • Does it work as well in the elderly who are not as capable of forming an immune defense as the rest of us are?
  • Does it work as well and as safely in all individuals regardless of their ethnicity since we know of other commonly used drugs that are either less effective or more dangerous due to the unique genetic differences between the different races?
  • Are there other health conditions one might have such as cancer or diabetes that might make the vaccine more detrimental than beneficial?
  • Is there a possibility that a vaccine could put some individuals at risk for an even more serious infection?  Unfortunately, you can put money on it that, even if and when one of these vaccines makes it to the market, we may not have definitive answers to all of these questions. Does that mean we should wait until we do?

Probably not as that would almost certainly take years and given how destructive and long-lasting this virus can be, it would cost us millions and millions of lives. If these next trials continue to exhibit the same promise that the early studies did, the prudent move would be to release them for use by the general public even if every “i” has not been dotted nor “t” crossed.

As for timelines, AstraZenica has already announced that it plans to start distributing doses to the U.S. and U.K. in September or October with the balance of deliveries likely to be made by early 2021. They will accomplish this aggressive timeline by taking the unprecedented and financially risky move of manufacturing the drug at the same time as their final clinical trials are underway. If the trials do not go as well as hoped, AstraZenica will have suffered significant and, perhaps, catastrophic monetary losses. However, if the trials are successful, they will be first to market and reap the rewards that come with it in a capitalist society.

We can debate the merits of all of that another day. For more information about this or any other drug related questions, contact your pharmacist.