Marie George, M.D. | Health matters: Answers to questions about a COVID-19 vaccine

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Editor's note: In this column, infectious disease specialist Marie George, M.D., of Southwestern Vermont Medical Center Infectious Disease, dives in to the complex and fascinating field of vaccine development and how it affects the potential for a COVID-19 vaccine.

Q: How many COVID-19 vaccines are in development now, and how are they similar or different from one another?

A: There are 135 different COVID-19 vaccines in development at companies, universities, institutions, research labs, and partner groups around the world. There are four major ways to develop a vaccine, and every method is in use.

- Genetic vaccines, which use the virus's own RNA or DNA

- Viral vector vaccines, which use a different virus to get COVID-19 genes into cells

- Protein-based vaccines, which use the proteins found on the outside of the virus

- Weakened virus vaccines. This type of vaccine has been very successful for developing resistance to many other diseases and is considered the safest form of vaccines.

The most exciting difference between the vaccines is a potential breakthrough in vaccine delivery. Traditionally, all vaccines have been liquids injected deep in the skin, but one contender from the University of Pittsburgh uses a finger-tip-sized patch, including 400 tiny needles made of sugar and applied to the skin like a Band-Aid, to deliver the protein-type vaccine.

In all cases, the vaccines are meant to either recruit cells to kill the virus or make antibodies against the virus. Some vaccines also include adjuvants, or ingredients that help strengthen the immune response among those who receive the vaccine.

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Q: What are the steps to getting a vaccine developed and produced?

A: Once the vaccine is designed and initial doses produced, the first step is preclinical testing, when the vaccine is tested in animals, ideally primates. If a vaccine stimulates a response and is found to be safe, it moves on to Phase I.

During Phase I the vaccine is tested in a small number of humans to determine if it's safe.

Phase II involves more humans to see if the vaccine creates a measurable immune response. Scientists continue to evaluate safety throughout the entire process.

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Phase III, the clinical phase, is last. This stage aims to measure the vaccine's effectiveness, whether it actually protects vaccinated people who are exposed. A vaccine can be effective in two ways: either it keeps a person from becoming infected at all or it lessens the risk of developing serious illness.

Q: How long does the development process usually take?

A: Typically, each phase takes months to years. The average time to complete them all is 4 to 5 years. In the case of COVID-19, scientists have been encouraged to combine phases to complete development faster. The most promising projects have even been given additional government resources and reduced regulatory pressure to generate the vaccine "at warp speed." As a result, infectious disease experts expect the vaccine for COVID-19 to take a lot less time. It is still too early to predict the release of a COVID-19 vaccine.

Q: What are the risks and challenges of developing a vaccine quickly?

A: Under typical circumstances, scientists would evaluate the vaccine's effectiveness in large groups with people of all ages and with different medical conditions over an extended time. In this case, though, they are measuring antibodies and ensuring that the antibodies neutralize the contagion. This is called an "immune correlate." Once identified, they are make educated assumptions, like whether the number of antibodies produced will be sufficient against the threat and how long the protection will last. While we would always prefer to have all the time we needed, scientists are performing a risk-benefit analysis. Because the benefit of having a vaccine is so high and the risks relatively low, they have decided it's worth speeding up the process.

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Q: Do you expect one clear winner? Is there a chance that no effective vaccine will emerge?

A: There is a very high likelihood that several of the vaccines in development will work to prevent disease and come into use. Over a few years, one may emerge as most effective, and companies may shift from making the less effective versions to the more effective one. And there is a small chance that no vaccine will emerge as safe and effective. But given how large the effort is and the different technologies being employed, infectious disease specialists are hopeful and optimistic.

Research for vaccines can fail—like those for SARS a few years ago, for instance. In that case, it was because the disease diminished on its own, the need for the vaccine decreased, and funding was cut. COVID-19 is not going anywhere. The interest, funding, technology, and partnerships are in place. It seems likely that at least one vaccine will be found.

Q: What is your prediction regarding when a vaccine will be available at all and when one will be available locally?

A: That's a hard one. It depends on how easy the approved vaccine is to make. What's remarkable in this case is that some companies are already producing millions of doses of vaccine, even before regulatory approval. They are the types that are relatively easy and inexpensive to make. The companies are betting that the vaccine they are making will be proven safe and effective. Once approved, they will have a head start on manufacturing and distribution.

Vaccines will be made available first to areas with high levels of infection. Vermont and the surrounding areas have relatively low levels of infection, so it may be a while. Those who are most susceptible, older people, for example, will also be prioritized.

Q: How would you imagine an effective vaccine would change our behavior in society?

A: Whether a vaccine will allow us to "return to normal" depends on how effective it is, how long it lasts, and its availability. Also, it might provide only partial immunity. Our mitigation efforts — handwashing, masking when near those outside our household, and keeping 6 feet from others — are our best defense right now and are likely to remain so for a long while into the future.


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