Official News Magazine of the Canadian Snowbird Association

 

So where do we stand with COVID-19?

by Dr. Denise Martin

 

These are challenging times, to say the least. As we have moved through these last several months dealing with the COVID-19 pandemic, it often appears that there are more questions than answers. To add to the uncertainty, there is a lot of misinformation circulating, which leaves many unsure in which direction they should turn. What is this virus? Will it disappear? Will there be a vaccine? It is hard to make decisions when we don’t have all of the information, but we are all doing our best as together, we sail through these uncharted waters.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 or 2019-nCoV) is the novel coronavirus that causes the disease which we call COVID-19. Coronaviruses are not new; they are usually associated with nothing more than the common cold in humans, though potentially having a devastating impact on other animal species. The strain that causes COVID-19, however, is unique in many aspects, including how easily it is transmitted.

Coronaviruses are so named due to the spikes on their surface that give the virus a crown-like appearance when viewed with an electron microscope (“corona” means crown). These spikes allow the virus to associate with receptors on cells that are targeted for infection. In COVID-19, these receptors are called ACE2 (angiotensin-converting enzyme 2) and there are many different cells that express this receptor beyond lung tissue. In addition to the lungs, ACE2 has been found in the heart, kidney, intestine and blood vessels, to name a few. This wide distribution is potentially part of the reason that the disease has such a diverse and wide-ranging impact on different individuals.

Many may recognize the term “ACE” or angiotensin as it is related to some of the medications used for control of hypertension − or high blood pressure. Because of this relationship, there have been theories that there is a higher risk of COVID-19 in people who are taking certain blood pressure medications. It should be noted that there is currently no evidence that people using the various antihypertensive medications are at a greater risk of contracting COVID-19 or having more severe disease.

SARS-CoV-2 is in a group of viruses that tend to mutate frequently. Some mutations of the coronavirus have already been seen. This is not to say that new, more pathogenic strains are emerging. This process is normal for emerging viruses and is not occurring in the COVID-19 virus any more rapidly than would be expected.

The challenge with viruses with high mutation rates is that it can, at times, be more difficult to design treatments that are highly effective. If a drug or a vaccine is specific for a particular part of the virus, then it is possible that it will be less effective if that part changes slightly. The flip side of a fast-mutating virus is that many mutations could actually make the virus itself less effective. A successful virus finds a balance between mutations that allow it to avoid drugs and the immune system and those that may render it less potent.

To have an effective vaccine, you want something that will initiate a substantial immune response, remain effective despite mutations and provide lasting protection. One of the “good” things about the novel coronavirus (in terms of producing a good vaccine) is that it causes a robust immune response when it enters the body. This means that when the vaccine is introduced to the body, it will cause a strong response that prepares it for battle when it encounters the real virus.

Many of the vaccines that are currently in development for COVID-19 target the interaction between the spikes on the surface of the virus and the ACE2 receptor on human cells. This is an ideal target for a vaccine because interfering with the interaction between the virus and its receptor can prevent the virus from entering the cell, multiplying and causing disease. Understanding this spike on the coronavirus has been a key part of developing a vaccine and its structure was resolved in record time. Because the virus spikes play an important role in getting the virus into the cell, it is predicted that they will not undergo a lot of mutation and still remain effective – making them an ideal vaccine target.

Getting long-lasting protection against the novel coronavirus may be the most daunting challenge. Infection with human coronaviruses does not always result in lasting antibodies that will protect you from a subsequent (re-) infection. Even though the disease may be mild or asymptomatic after antibody levels wane, it is not known if these individuals would still transmit the virus. This will have to be addressed in vaccine trials, as this would be a significant issue if the virus becomes endemic.

Despite the record pace of vaccine development for COVID-19, time is still needed to ensure efficacy, safety and accessibility. Simultaneous, as opposed to sequential activities in the development process can help to shorten timelines, however a certain amount of time is still needed to ensure that the vaccine has the desired impact. New production technologies, increasing capacity and distribution must also be taken into consideration.

It is still early in the trajectory of this pandemic and too soon to expect effective tools such as drugs or vaccines to be widely available. Cautious optimism seems to suggest that we will have good information about some of the vaccines currently in trials by early next year. The nature of this virus, as we continue to learn more, is such that it is not likely that a vaccine will be a ‘silver bullet’ and public health measures will continue to be important. Our best strategy right now is to direct concerted efforts towards limiting the spread of the virus, protecting those at high risk and providing supportive care for those affected. Previous experience suggests that in the first few years of a pandemic, there is an ebb and flow as population-level immunity develops, either through vaccination or community transmission.

It is also important to remain vigilant. Not only in our activities, but also with respect to information. In a context where both public health and science are important for success, access to knowledgeable, credible information about COVID-19 will be essential.

 

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