Can We Really Develop a Safe, Effective Coronavirus Vaccine?

We don’t know for sure, but if we can, it probably won’t be easy, cheap or fast

In the event of any infectious disease outbreak, our minds turn to vaccines and they do so for good reason. They can safe in most cases, relatively expensive and have worked pretty well for diseases including smallpox, polio, yellow fever, and, most recently, Ebola.

Scientists suggest the Coronavirus has already mutated into 30+ strains.  Drug and vaccine development, while urgent, need to take the impact of these accumulating mutations into account to avoid potential pitfalls.  Researchers said the findings show the true diversity of the viral strains is still largely underappreciated.

Also, many scientists think this might make it difficult for a vaccine that’s created in a year from now.  It might not be the vaccine that’s effective because it won’t be targeting the right molecule, and it’s targeting could change a little bit.

The CDC used to cite that the flu vaccine was 70-90% effective from 2004-2016. I was quite surprised to see this chart below when I looked at the CDC web site showing 10-60% effectiveness. Clinical Infectious Disease Flu Vaccine
Real-time tracking of pathogen evolution. Nextstrain is an open-source project to harness the scientific and public health potential of pathogen genome data. We provide a continually-updated view of publicly available data alongside powerful analytic and visualization tools for use by the community. Our goal is to aid epidemiological understanding and improve outbreak response.

Will a vaccine come as easily for the novel coronavirus? The answer is maybe yes, maybe not. The “maybe yes” comes from the observation that in animal studies, coronaviruses stimulate strong immune responses, which seem capable of knocking out the virus. Recovery from COVID-19 may be in large part due to effective immune response. The “maybe not” comes from evidence just as strong, at least with earlier SARS and MERS viruses, that natural immunity to these viruses is short-lived. In fact, some animals can be reinfected with the very same strain that caused infection in the first place.

This raises more crucial questions with equally ambiguous answers. If a vaccine does prove to be effective, would it be effective for long?  How long will it take to develop a vaccine in the first place?  Will herd immunity be more effective?  Did Sweden get it right with regards to public policy?

Here is an Example of How the Flu Virus Can Change: “Drift” and “Shift” from CDC.  Influenza viruses are constantly changing. They can change in two different ways and thus why flu vaccines are not always effective.

One way influenza viruses change is called “antigenic drift.”  The small changes that occur from antigenic drift usually produce viruses that are closely related to one another, which can be illustrated by their location close together on a phylogenetic tree. Influenza viruses that are closely related to each other usually have similar antigenic properties. This means that antibodies your immune system creates against one influenza virus will likely recognize and respond to antigenically similar influenza viruses (this is called “cross-protection”).

However, the small changes associated with antigenic drift can accumulate over time and result in viruses that are antigenically different (further away on the phylogenetic tree). It is also possible for a single (or small) change in a particularly important location on the HA to result in antigenic drift. When antigenic drift occurs, the body’s immune system may not recognize and prevent sickness caused by the newer influenza viruses. As a result, a person becomes susceptible to flu infection again, as antigenic drift has changed the virus enough that a person’s existing antibodies won’t recognize and neutralize the newer influenza viruses.

Antigenic drift is the main reason why people can get the flu more than one time, and it’s also a primary reason why the flu vaccine composition must be reviewed and updated each year (as needed) to keep up with evolving influenza viruses.

The other type of change is called “antigenic shift.” Antigenic shift is an abrupt, major change in an influenza A virus, resulting in new HA and/or new HA and NA proteins in influenza viruses that infect humans. Shift can result in a new influenza A subtype in humans. One way shift can happen is when an influenza virus from an animal population gains the ability to infect humans. Such animal-origin viruses can contain an HA or HA/NA combination that is so different from the same subtype in humans that most people do not have immunity to the new (e.g., novel) virus. Such a “shift” occurred in the spring of 2009, when an H1N1 virus with genes from North American Swine, Eurasian Swine, humans and birds emerged to infect people and quickly spread, causing a pandemic. When shift happens, most people have little or no immunity against the new virus.

While influenza viruses change all the time due to antigenic drift, antigenic shift happens less frequently. Influenza pandemics occur very rarely; there have been four pandemics in the past 100 years. For more information, see pandemic flu. Type A viruses undergo both antigenic drift and shift and are the only influenza viruses known to cause pandemics, while influenza type B viruses change only by the more gradual process of antigenic drift.

The history of vaccines also shows that Government policies based around mandating vaccines are political

You might also enjoy this article: Why We Need a Placebo Covid-19 Vaccine

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