Official News Magazine of the Canadian Snowbird Association

 

The Race Toward a Vaccine

by  Dr. Denise Martin

 

Month after month of mask-wearing, social distancing and limits to our normal activities have been exhausting. The COVID-19 pandemic has been extraordinary in its disruption of our daily lives, and has taken a tremendous toll on our friends, our families and our society. All of us are waiting for a sign of hope, some indication that there will be a point at which we can return to some kind of normal. Many of those hopes are pinned to the widespread availability of a vaccine.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, emerged late in 2019 and has spread across the globe, despite elaborate efforts to contain the infection. The highly contagious nature of the virus has presented a difficult challenge for many mitigation efforts. A safe and effective vaccine is an important part of the strategy to reduce the risk of severe disease and mortality due to COVID-19.

To the credit of international organizations, governments and scientists around the world, the push towards a vaccine has proceeded at an unprecedented pace. The virus was isolated in January 2020 and, within a couple of months of sequencing the genes of the virus, early phases of clinical trials were underway. By comparison, it has taken more than 40 years to develop a vaccine for the Ebola virus. The average time to develop a vaccine is approximately 10 years. The rapid pace of progress towards a vaccine for COVID-19 is a testament to impressive advances in technology and what can be accomplished with international and scientific co-operation. While the world waits somewhat impatiently for what may feel like an eternity for the discovery and rollout of an effective vaccine − within the ambitious time frame of 18 months − developments that have occurred thus far are monumental.

There are currently more than 150 candidate vaccines in various stages of development, with more than 30 candidates having moved to the clinical trials stage. Each of these vaccines has a different way of stimulating the immune system so that the body is prepared when it encounters the coronavirus. Among the many strategies that are being investigated, some vaccines carry genetic material from the virus, some carry fragments or pieces of the virus, and still others use a weakened form of the virus. New vaccine technology platforms are being considered as part of the initiative to develop a fast, safe and effective vaccine for COVID-19. Each approach has both strengths and weaknesses, and having options to choose from is a definite benefit.

While there are many vaccines in the pipeline that look promising, the clinical trials process is a daunting one. Pre-clinical trials establish the potential for an effective vaccine in animal models, followed by multiple stages of safety and efficacy testing in specific human populations. In the latter phases, these clinical trials require thousands of participants in order to generate high-quality data that can be used to determine if a vaccine is truly effective and what level of protection it offers. Normally, the success rate for vaccine development is around 6%.

One of the new technologies that is being considered for COVID-19 uses messenger RNA (mRNA) to prepare the body’s immune system before exposure to the virus. This mRNA delivers instructions to the cells of the body so that your cells can make specific pieces of the virus. These pieces, called antigens, are recognized by your immune cells and help to train your immune system defence. When a person comes into contact with the real virus, the body is ready. Production of mRNA vaccines does not involve infectious elements and they may be manufactured relatively quickly and at a lower cost than some of the other, more conventional approaches.

Despite the enormous challenges, data are emerging that safe and effective vaccines may be on the horizon. While the world is eager to have useful tools in our fight against this virus, independent review of clinical trial data will be necessary. How effective is the vaccine? Does it work well in different populations – young adults, older adults, children, people with underlying conditions? Are there any serious side-effects? These, and other questions, will have to be answered in order for governments and regulatory bodies to decide if a candidate vaccine is appropriate for use in the population. A vaccine that protects people from disease, and reduces the severity of disease in those who do contract it, is obviously desirable. As one can imagine, the quantity of data to be reviewed will be substantial. Even with expedited processes in some contexts, this will take some time.

To help reduce some of the time required to implement a vaccination strategy, developers may be scaling up vaccine production simultaneously with other activities needed to bring a vaccine to market – processes that would normally occur sequentially. Once a vaccine has been approved, manufacturing, distribution and plans for delivery and administration will move into high gear. If multiple vaccines are approved for use, that could help with supply issues. In North America alone, hundreds of millions of people need to be vaccinated, and the demand for an effective vaccine is worldwide.

The complex practicalities inherent in a massive vaccination campaign during a pandemic cannot be overstated. Depending on the successful vaccine candidate, multiple doses may be necessary.  Vaccinating millions of people not once, but twice, to confer effective immunity, increases the logistical challenges. Different vaccines will have different storage requirements, with potentially significant implications for distribution. Refrigeration, or the need for specific freezing temperatures, may determine how vaccine administration will roll out.

The question of vaccination priority will also impact how soon different individuals will have access to an effective vaccine and how soon social restrictions might ease. People at high risk and front-line workers will be among the first to have access to the vaccine. This will likely include seniors and those with high-risk health conditions. Those who are involved in essential services may also be prioritized. It is unclear when children will be vaccinated, as most trials have focused on healthy adults; studies in children are ongoing. Vaccine supply will build gradually. It will likely take some time before all of those who need to be vaccinated have access to the vaccine. Early estimates suggest that 60-70% of the population needs to be vaccinated against SARS-CoV-2 to achieve herd immunity.

Recent developments suggest that safe and effective vaccines for COVID-19 may soon be moving through the approval process. The vaccine needs to both be safe, and produce an immune response to the virus adequate to prevent infection or severe infection. This, however, is not the end of our pandemic journey. Regulatory bodies conduct ongoing surveillance to monitor efficacy and safety of a vaccine as it is distributed among the wider population. It is yet to be determined how long immunity will last with the new vaccines. Previous experience with this type of virus suggests that immunity may wane with time and yearly or biennial immunization may be necessary. Due to the immense scale of the vaccination program that needs to be implemented, as well as the associated practical and logistical considerations, it is clear that public health measures to mitigate viral spread will remain a priority for some time. Mass production, distribution and administration to a majority of the population will take time, once a vaccine has been approved. Long-term observations will ensure that the vaccine functions as expected. While it may not be time to discard our masks and hand sanitizer just yet, it does appear that some help is on the way.

 

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