The global havoc wreaked by the coronavirus pandemic has led to an unprecedented push for a vaccine to slow the spread (and hopefully end the threat). Currently, there are about 150 efforts taking place around the world, with about a dozen already undergoing clinical trials in humans. By the end of 2020, it’s believed there will be another 50 or so drugs undergoing testing. Which one(s) will ultimately prove successful depends largely on technology.
Pros & Cons of Different Vaccine Types
Since nobody knows which technologies will work best, scientists are developing a multitude of potential vaccines in order to improve their chances of finding a successful cure. Vaccines work by triggering an immune system response against a specific pathogen, thereby protecting the individual should that pathogen appear in the body. The genetic sequence of the virus responsible for COVID-19 was identified early on by the Chinese, spurring immediate efforts to develop a vaccine that would target the distinctive “spike protein” on the virus.
Typically, it takes researchers 15-20 years to develop a vaccine. Because COVID-19 has affected the health and economies of individuals and countries across the globe, scientists are hoping to have a vaccine in place in a mere 12-18 months. This Herculean effort is largely dependent upon new and emerging technologies, each with their pros and cons. Complicating matters is the fact that there are so many unknowns with the coronavirus; it seems we are learning something new about it every day.
Some of the leading contenders, and their strengths and weaknesses, include:
- Whole virus vaccine: Live-attenuated. This type of vaccine has a long and proven track record of safety and efficacy and has been used to fight measles, mumps, and rubella (MMR) for decades. Even the small percentage of people who end up infected anyway experience less-severe symptoms. However, in theory, these vaccines can cause the disease they were developed to prevent. Finding the proper balance often takes years.
- Whole virus vaccine: Killed. The killed version of a whole virus can’t cause the disease it protects against; polio and rabies vaccines are examples. However, certain vaccines that utilize killed forms of virus have made people susceptible to harsh and unusual immune system responses.
- Protein-based vaccine. These vaccines are safe, effective, and easy to manufacture. Examples include shingles, hepatitis B, and human papillomavirus vaccines. But they must be paired with an immune stimulant, setting up the potential for unpleasant side effects. They are also effective for shorter durations than other vaccines.
- Viral vector vaccines. These vaccines initiate a strong immune system response, increasing their effectiveness. However, they can cause other, milder illnesses, and are unable to reproduce once inside a person’s cells, which means they require a large number of viral particles—some of which the immune system has already built up an immunity toward, meaning it will attack the beneficial virus particles. The Ebola vaccine is one example of this type.
- Nucleic acid vaccines. One of the newest vaccine types works by delivering strands of genetic material to the immune system to aid in its fight. Nucleic acid vaccines can be developed quickly, but because they are in their infancy, have never been tested on large numbers of people before, raising questions about their safety and effectiveness. It’s likely that additional doses and frequent boosters would be required to maintain immunity. Large-scale production may be an uphill battle, as well.