I confess I was writing a summary of my articles on SARS-CoV-2 and it has not been going well, but in the meantime my colleagues Kelly Kandra and Elias Olsen and I have made a video. (It is a little stiff, but we will get better at it.) When this infection started, only one scientific paper about it had been published, and that was in The Lancet, the British medical journal. And the SARS-Cov-2 sequence had arrived at the NIH on January 10, 2020. The stories of the first scientists who discovered the disease and sequenced the virus are heroic because they were doing science in an authoritarian society, and that can be scary. The intense effort continued in labs and hospitals around the world. There are now tens of thousands of papers and we know a lot about the biology of the coronaviruses and how to confront them.
Most important, we have several vaccines and more specialized ones on the way. There have been few adverse effects, but people wisely have questions. One is about side effects, which to date have been minimal. Second shots of the Moderna and Pfizer vaccines sometimes cause a day of slight fever. So do other vaccines; it’s a small price to pay.
What about efficacy? No person, not even old people, who got properly vaccinated died of COVID-19. The clinical trials were thorough and convincing. They involved 30,000 people in the Phase 3 trials. In fairness, clinical trials cannot pick up an event that occurs once in a million vaccinated people.
Are these vaccines safe if they were made so quickly? Yes. With older vaccines we did not know why or how the virus was weakened. Scientists had to infect cells or animals with the measles, mumps, and rubella viruses over and over until they found a mutant that could provoke an immune response without hurting an animal or person. That takes years. Before we could determine the sequence of a virus, we did not really know what in the virus has been changed to make it harmless. The new mRNA technologies avoid that problem and save a lot of time.
For example, poliovirus has about 6,000 letters in its genome and we did not know how many had been changed in the weakened but still live Sabin vaccine. When only one or two of the 6,000 letters in the genetic instructions are changed, the virus can occasionally mutate back to a dangerous form. When Prof. Vincent Racaniello, my colleague at Columbia, sequenced the genomes of the dangerous virus and the weakened virus, he found only a few changes. A virus with many changes will never revert to a dangerous form.
With mRNA technology, scientists know the sequence and have deleted all of the genes except the one that codes for the Spike protein. The mRNA that is injected cannot make virus; it can only make Spike protein, which still excites the immune system to form antibodies and T cells that inactivate the SARS-CoV-2 virus. The existing vaccines deal with all current variants (mutations) of the Spike protein. Virologists are keeping close watch for new variants: in May 2021, the sequences of a million different SARS-CoV-2 viruses had been sent to a special database as part of a project to stay ahead of dangerous changes in the virus.
Many new vaccines will be made using this mRNA technology, including ones for Zika, Ebola, Respiratory Syncytial Virus, and many others. Let me add that there are additional new and promising ways to make vaccines.
Let us know if the video is useful, and the scientific subjects people want to read about, assuming COVID-19 cases continue to decline. My thanks to Elias Olsen and Kelly Kandra.
I will write a longer article or teach a course, and there will be more videos, but for the moment, like many people, we are going to see our grandchildren.
To watch the video, click here.
Rich Kessin is Emeritus Professor of Pathology and Cell Biology at the Columbia University Irving Medical Center. He writes frequently for The Edge, and his previous articles and letters can be found here.
