How many vaccines are in the pipeline and how many are being tested in people?
Right now, more than 100 COVID-19 vaccine candidates are in different stages of development. Of those, over 40 are being clinically evaluated, meaning they are being tested in people. This reflects an extraordinary, global mobilization of resources.
What’s involved in testing a vaccine and how is the process being sped up?
It starts with testing in the laboratory and tests in animals before we move into clinical trials that involve people. With clinical trials, we start with Phase 1 studies. They involve a small number of people and help determine the vaccine’s safety and immune response. Normally that takes a year to 1½ years. In Phase 2 testing, the vaccine is given to a slightly larger pool of patients to continue to see if it is safe and well tolerated and to determine the best dosing schedule, and if the immune system is having the desired responses. Normally, that can last up to two years. In Phase 3 trials, we test the vaccine in thousands of volunteers for safety and to see if it is effective and protects them from infection or from severe cases of COVID-19 illness so that they’re less sick and less likely to transmit it to others. At this point, four vaccines are in Phase 3 trials in the United States.
None of the required steps are being skipped, but many are being done on a parallel timeline instead of one after the other. So instead of taking a few years, the studies can be completed in months. But the vaccines are still going through the very careful phases of testing and monitoring to make sure they’re safe, and many groups, including the Food and Drug Administration (FDA) and independent safety monitoring groups of experts, oversee the safety of each study in progress. Some companies have already begun to manufacture the vaccines, so they will be prepared to make more doses if the trials show they are safe and effective.
How would a COVID-19 vaccine work?
The fundamental concept is to teach the body’s immune system to recognize and fight off the virus when and if the body comes into contact with it. So when the body is exposed to the virus later, it mobilizes parts of the immune system — T cells and antibodies — to prevent infection or reduce the severity of the disease. Most COVID-19 vaccines contain copies of pieces of the virus that are made in the laboratory and delivered to the body to teach it to recognize the virus. Then the body can mount an immune response and be ready to attack when the real thing comes along.
What should we take away from recent news about Pfizer’s vaccine?
The announcement that the Pfizer vaccine was found to be more than 90% effective in preventing COVID-19 in participants without evidence of prior SARS-CoV-2 infection is very exciting and energizing news.
It’s important to keep in mind that these data are based on an early interim analysis by an independent group of experts. This early analysis, based on 94 individuals in the study (out of about 44,000) who developed COVID-19, compared how many cases occurred in the vaccine group and how many occurred in the placebo group. To make sure that these results hold up and to follow participants for safety, the clinical trial will continue to the final analysis. But 90% is a very good result and definitely higher than what we see from influenza vaccines, which are 40% to 60% effective.
It’s also important to remember that the vaccine is not FDA-approved yet. After the company submits an application for Emergency Use Authorization, the FDA will carefully review the safety and effectiveness data. But it is possible, if everything goes as planned, that this vaccine could have emergency authorization for certain high-risk populations before the end of the year. It will take some more time to make it available for the general public.
We will likely need more than one safe and effective vaccine, since there is substantial need and we must make sure we have enough options to protect different age groups and diverse populations. An important consideration is how vaccines are stored and distributed; the Pfizer vaccine has to be kept at very cold temperatures. And that’s another reason it will be important to have more than one option for different settings.
Which vaccines are being tested at NewYork-Presbyterian?
The vaccine being tested at NewYork-Presbyterian/Weill Cornell Medical Center is an RNA-based vaccine developed by the company Moderna and the National Institutes of Health. At NewYork-Presbyterian/Columbia University Irving Medical Center, we are doing a study to test the AstraZeneca/University of Oxford vaccine. It uses a weakened chimpanzee version of a common cold virus called adenovirus as a “carrier” to introduce a copy of a key protein of the SARS-CoV-2 spike protein so that when the body later encounters the SARS-CoV-2 virus, it remembers and attacks it.
Both campuses began testing the vaccines in people late this summer. ln the AstraZeneca trial, a voluntary pause was triggered in the United States to investigate a safety event that occurred in England. The study recently restarted after the FDA and an independent Data and Safety Monitoring Board completed a thorough review of all the safety data from trials using this vaccine and concluded it was safe to resume the study. Study pauses are not uncommon; they are a normal part of the clinical trial process and show that the careful oversight process is working. We will likely test other COVID-19 vaccines in the future.