Peter L. Salk, M.D., is president of the Jonas Salk Legacy Foundation, a professor in the department of infectious diseases and microbiology at the University of Pittsburgh Graduate School of Public Health, and the eldest son of Jonas Salk.
Now that the first vaccines capable of protecting against the development of severe COVID-19 disease caused by the SARS-CoV-2 virus have begun to roll out in Canada and other countries, there is a palpable sense that relief from the pandemic may be in sight. The onslaught of this viral illness, that came with little warning, has left a path of misery and unsettledness in its wake. Those who have not been affected directly by death and disability among family and loved ones are likely to have suffered an economic toll. And nearly all of us are mourning a freedom lost in the face of the societal restrictions that have become necessary in order to tamp down the rate of spread of this unsparing illness.
Humanity has faced moments like this in the past, but in earlier times there were few defences that could be erected to protect the citizenry. For example, outbreaks of bubonic plague in Europe in the 14th century reduced the population on that continent by a third or more, and the disease returned in wave after wave. One of the great blessings of our present era is the advent of vaccines capable of preventing a wide range of infectious diseases. Those of us in my age range carry a memory of one of the most dramatic experiences of a vaccine changing the tenor of the times.
Poliomyelitis, a paralytic disease affecting primarily children, had become an epidemic illness as a result of improved sanitation that deprived children of early exposure to the virus while still protected by antibodies passed on to them by their mothers, both prior to birth via the placenta, and afterward via the mothers’ milk. As a consequence of improved hygiene, children ended up being exposed to polioviruses later in life after the protective antibodies obtained from their mothers had disappeared.
The viral illness that ensued could kill nerve cells that controlled muscles in various parts of the body, such as the arms, legs or torso – in the latter case preventing an individual from breathing without external respiratory support provided by an “iron lung,” in which a person might need to reside for days, weeks or years, if they indeed survived the paralysis that followed the initial infection.
Parents lived in fear of the summer epidemics of polio that struck without warning, and that had increased in severity over the decades. The worst year in the United States was in 1952, with nearly 58,000 cases and more than 3,000 deaths, while the worst year in Canada followed in 1953, when there were approximately 9,000 cases and 500 deaths.
My father, Jonas Salk, moved our family to Pittsburgh in 1947, following the successful work he had undertaken with Thomas Francis, Jr. and his team at the University of Michigan in creating the first vaccine against influenza – another devastating epidemic illness. Along with his research team at the University of Pittsburgh, he soon found himself at the forefront of research toward the development of a polio vaccine, supported by the March of Dimes. In 1952, a first set of studies of an experimental vaccine preparation, consisting of inactivated viruses, was initiated at a rehabilitation institute outside of Pittsburgh in children who had already had polio. Results of these studies suggested that a vaccine of this type might well prevent the disease. He injected us, his own family, the following year – and after additional trials in around 7,500 Pittsburgh schoolchildren in early 1954, a massive field trial took place in the U.S., Canada and Finland, with more than 1.8 million children taking part in the U.S. portion of the trial.
Nearly a year after its inception, the results of the field trial were announced on April 12, 1955 – the 10th anniversary of the death of U.S. president Franklin Roosevelt, who himself was believed to have been paralyzed by the disease. When the public learned that the vaccine had proven safe, effective and potent, jubilation reigned. The pall of fear had been lifted: Once the vaccine was put to use, it would soon never be necessary to fear the ravages of polio again.
Canada had played a crucial role in facilitating the development, testing and production of the vaccine. The ability to grow the poliovirus in the laboratory in order to prepare the vaccine efficiently was significantly aided by the use of a special growth medium developed at the University of Toronto’s Connaught Medical Research Laboratories. A Connaught scientist also developed an efficient method for growing the virus on a large scale. As a result, all of the poliovirus used in preparing inactivated poliovirus vaccine for testing in the 1954-55 field trial was grown at Connaught and shipped to two pharmaceutical firms in the U.S. for inactivation and bottling.
Altogether, it had taken seven years between the initial work on polio in my father’s lab and the realization of a vaccine, and another six years before a second polio vaccine, based on the oral administration of live but weakened polioviruses, was introduced.
The world of vaccines is entirely different today, some 65 years later. Within less than a year of the appearance of SARS-CoV-2, two vaccines have been introduced using RNA sequences from the virus (the part of the virus’s genetic material that codes for the so-called “spike” protein on the surface of the virus) to stimulate a protective immune response in vaccine recipients. This technology is entirely new, and did not exist in the polio days. It allows much more rapid development, production and testing of vaccines that use that method. A third vaccine is about to be introduced in Britain, using harmless common cold viruses as carriers of similar genetic sequences – also a much more rapid method of producing a new vaccine. A similar such vaccine has already been introduced in Russia, and candidate vaccines produced in China using either that technique or the old-fashioned “killed virus” technique are poised to be introduced. Many other vaccines using one or another analogous methods, or using purified virus proteins together with adjuvants (chemicals that help stimulate stronger immune responses), are in the pipeline.
Despite the promise of all of these vaccines, many people are still hesitant to take advantage of them as they become available. Some have been concerned about the speed with which the vaccine projects have been undertaken, worrying about whether corners have been cut with respect to safety. Others, particularly racialized communities in both Canada and the U.S., carry suspicions about the government and medical institutions, based on past experiences, that may render them leery of lining up to take something new. Yet others are opposed to vaccines in general, based on fears that they are inherently dangerous and can cause maladies in otherwise healthy individuals.
It’s important to recognize that vaccines have, in the past, at times caused either unexpected – or perhaps even expected – problems, that have led to careful re-evaluation and either modifications or discontinuation of their use. One example is the second (“live”) polio vaccine, which infrequently causes polio in vaccine recipients or their close contacts owing to the appearance of mutations in the weakened viruses that cause them to regain their virulence. Such mutations can allow the vaccine-derived viruses to spread and cause outbreaks of paralysis identical to those seen with naturally occurring polioviruses. This vaccine is no longer used in either Canada or the U.S. because of this drawback, although it is still used in many countries for which it has been the most practical choice. However, it is also important to understand that many of the fears surrounding vaccines are based on perceived problems that don’t stand up to scrutiny – for example, the idea that vaccines are responsible for causing autism. Used carefully and correctly, vaccines have changed the way we live our lives, free from the scourges of many diseases that used to plague us. The same could be true with respect to the COVID-19 pandemic we are contending with today.
As we move forward in our efforts to bring the present pandemic to an end, we must keep in mind not only our own needs for immunizing the populations of our respective countries, sheltered here in the wealthy areas of the northern part of the Western Hemisphere, but also the needs faced by less affluent countries throughout the world. If we think only of ourselves, garnering supplies of what at present are scarce vaccines just coming out of production (Canada, for example, has purchase options for supplies of COVID-19 vaccines sufficient to vaccinate the country’s population five times over), other less affluent countries may be left to fend for themselves, unable to procure enough vaccine to immunize their populations fully until another four years have passed. It’s not only in the interest of these other parts of the world that vaccines should be available globally; it’s in the interests of affluent countries such as ours as well, to which this virus can spread again should our own guard be let down.
My father died 25 years ago. Were he still here, he would be amazed to see what has happened in terms of our ability to mobilize our technological capacities and, ideally as well, our economic capabilities and the generous side of our natures. We have it within us to stop a modern plague that is affecting the entire world. We should all feel proud of how far we have come in our ability to shape our world in a positive way, and do what we can to help bring this current pandemic to an end.
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