Virologist discusses SARS-CoV-2 vaccine development, challenges for scientific community

Dr. Constantinos Kyriakis, assistant professor in the College of Veterinary Medicine’s Department of Pathobiology, discusses the role of vaccines in protecting against COVID-19 and helping prevent the spread of the novel coronavirus, as well as the unique challenges scientists are facing in developing safe, effective vaccine candidates. His research, primarily focused on ­zoonotic influenza viruses and novel vaccine technologies for more than a decade, will soon involve a minimally invasive study of a variety of COVID-19 vaccine candidates’ ability to trigger an immune response in swine when used alone or in combination with adjuvants.

Will social distancing, quarantine and isolation alone help control and eradicate SARS-CoV-2?

When applied at the right time, social distancing combined with quarantine and isolation of infected individuals are the most efficient non-pharmaceutical intervention tools that can slow down an epidemic and help the healthcare system cope with increased numbers of patients. This is what epidemiologists describe as “flattening the curve.” However, considering that SARS-CoV-2 might become an endemic seasonal pathogen like influenza, other tools, specifically vaccines and, to a lesser extent, antiviral drugs, will be required to reduce virus transmission, morbidity and mortality.

What is a vaccine and why is it important for this novel coronavirus pandemic?

A vaccine is a biological product delivered to humans or animals which provides immunity to a specific infectious disease. While there are several vaccine technologies, viral vaccines usually contain or generate parts of a given virus, known as antigens, that the immune system will recognize and then produce neutralizing antibodies against the target virus. Developing and deploying safe and effective vaccines against SARS-CoV-2 is of paramount importance. Mass vaccinations will help built what is known as “herd immunity,” the cornerstone of infectious disease control. This will not only protect individuals from the virus but the entire community and, importantly, high risk groups, including the elderly and people with preexisting health conditions.

How does development of a vaccine for SARS-CoV-2 differ from the development of other vaccines like the flu vaccine?

Unlike influenza vaccines, there are no licensed vaccines against any coronavirus in humans. In 2009, when the H1N1 influenza pandemic virus emerged, there were influenza vaccine platforms already established that had been in use for decades and that were proven very safe and effective. It was therefore relatively easy to produce and deliver vaccines against that influenza virus within a few months. With SARS-CoV-2 there are only limited data from experimental vaccines designed against SARS-CoV-1 and MERS-CoV, two related coronaviruses that emerged in 2002 and 2013, respectively, and caused limited epidemics. These experimental vaccines were tested in animal models and only one vaccine was tested in a phase I human clinical trial. Therefore, developing a safe and efficacious vaccine against SARS-CoV-2 is a major challenge for the scientific community. Testing vaccines in animal models is extremely important. Using reliable animal models allows us to identify target antigens, optimize the vaccine dose and formulation and, thus, move to human clinical trials with only the best vaccine candidates.

As universities and pharmaceutical companies work around the clock to find a vaccine for SARS-CoV-2, what is the likely timeframe for a vaccine to become available for the public?

As Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has been explaining in recent statements, a vaccine will not be available for at least twelve to 18 months. This is a realistic timeframe, as long as at least one of the current vaccine candidates is proven to be safe and effective. It is important to understand that the established licensing procedures are exhaustive and time consuming to ensure the vaccine that will be deployed is very safe and highly efficacious.

What is the process for vaccine approval? Is it possible to amend this process to lessen the time needed to develop a vaccine to stop the spread of SARS-CoV-2?

Typically, the development of a new vaccine from concept to approval consists of the following stages: (a) the exploratory stage during which the specific antigen and vaccine type are identified and developed; (b) the pre-clinical stage, in which the safety and efficacy of the product are tested in cell culture systems and in animal models; and (c) three clinical trial phases (I, II and III) during which the vaccine is tested in humans. In a phase I clinical trial, a small group of healthy individuals receive the vaccine and are monitored to confirm the safety of the product and determine if it elicits the appropriate immune responses. A phase II clinical trial is conducted using a larger number of participants, which includes individuals with increased risk of contracting the disease. During this phase, participants will be randomly selected to receive a placebo in place of the vaccine candidate. This critical step offers information about both the safety and, importantly, the efficacy of the vaccine. Finally, a phase III clinical trial is the most extensive step in this process. There are thousands of participants during this randomized and double-blinded study, with some participants receive a placebo instead of the vaccine. This is the longest, most critical stage that will offer extensive information about the safety and efficacy of the vaccine. Every phase of this procedure is extremely important, must be conducted carefully and in a timely fashion. Considering sufficient time is needed to produce the vaccine once these development and testing phases are complete, it is easy to understand why it will take so much time for a vaccine to become available. All of these steps take time and are critical to ensuring safety and effectiveness of the final product. It would not be wise to abbreviate the process.

About Dr. Constantinos Kyriakis

Dr. Constantinos Kyriakis, an assistant professor in the College of Veterinary Medicine’s Department of Pathobiology, holds both a doctor of veterinary medicine degree and doctorate in virology and vaccinology.