This article, about COVID Vaccines, was written and contributed by Mark Wallace, MD, Infectious Disease specialist | Skagit Regional Health | January 7, 2020
Development of SARS-2/COVID Vaccines
COVID has profoundly altered our lives. Efforts to slow the pandemic with masking and social distancing have been helpful, but cannot end it. Only the achievement of herd immunity, when 70 to 90 percent of the population is immune due to resolved infection or immunization, can bring the pandemic under control. Herd immunity through infections would likely cause another half to one million deaths. Fortunately, the past several months have seen the development of multiple types of SARS-2/COVID vaccines, two of which have already been approved in the U.S., and it is likely that several more will become available in early 2021.
COVID Vaccines in Human Trials
Most traditional vaccines are either inactivated (killed) or attenuated (weakened) versions of the infecting microbe. Vaccine development, utilizing recent advances in cellular biology, immunology, virology and manufacturing, has provided new types of vaccines that can be quickly tested and deployed. Sixty-four COVID vaccines are now in human trials and 19 are in the last stages of testing.
Two messenger RNA (mRNA) vaccines
Two messenger RNA (mRNA) vaccines (made by Moderna and Pfizer) have already been approved by the Food and Drug Administration (FDA) for emergency use. These mRNA vaccines bring genetic directions to the cytoplasm (not the nucleus) of cells and direct production of the SARS-2 spike protein. Within days of injection, the mRNA is destroyed while the spike proteins produced in our cells stimulate the immune system to produce a protective response.
Vaccines Under Development
Viral vector vaccines (several under development) are similar in that they use a different modified virus which cannot replicate in the human body to deliver genetic code to our cells, once again causing spike protein production that stimulates a protective immune response. The most well-known of these vaccines is the Astra Zeneca vaccine just approved in the U.K. It is important to note that neither the mRNA nor viral vector vaccines change or alter the human genetic code. Given that only the spike protein is produced, the virus cannot reconstitute or replicate in our body.
Many other types of vaccines are in late development. Protein subunit vaccines use lab-produced spike protein (again, just a part of the virus) which is injected to produce the immune response. Two are close to reporting final trial results and could quickly become key weapons in vaccine efforts. Traditional inactivated virus vaccines are being produced in China and one was approved there recently. Other vaccines, including an attenuated vaccine and various DNA vaccines are under development.
COVID Vaccines Tested in Huge Trials
Vaccines are tested in huge trials (30,000-60,000 patients) to gauge efficacy and safety. Efficacy means simply that the vaccine prevents the disease and is easy to determine. In both the mRNA vaccines in use in the U.S. today, the study subjects who received the two doses of the active vaccine had a 94 percent reduction in clinical COVID cases as compared to placebo recipients. The Russian adenovirus vaccine (Sputnik 5) has reported a 90 percent efficacy, and the Chinese (SinoPharma) inactivated vaccine is reportedly 79 percent protective. The vaccines can be safely given to those who have recovered from COVID, but vaccination should be delayed 90 days after resolution of the illness.
Safety is harder than efficacy to determine, as large numbers of vaccine recipients need to be followed over time. So far, all 19 vaccines in advanced trials appear quite safe. The two mRNA vaccines currently available have caused rare (about 1 in 100,000 injections) severe but nonfatal allergic reactions as the most notable adverse event. Many people have had less severe reactions such as a day of arm soreness, headache, fatigue or fever. It is also possible that additional, very rare side effects (~1 per million) will turn up as vaccine rollout continues. This should surprise no one, as all approved vaccines have risks.
Much Remains to be Learned
Much remains to be learned as the vaccines continue into widespread use. Are they as useful and safe in children, pregnancy and immunosuppressed people? So far, the evidence says yes, but more data are needed. Will they produce sterilizing immunity, meaning you can’t acquire or transmit virus after vaccination? Will viral evolution defeat the vaccines in the near future or will protection be long-lived?
Resembling Normal in 2021
John Huston Finley, a professor and university president in New York, said: “Maturity is the capacity to endure uncertainty.” While we cannot yet answer all coronavirus questions, we do know that the early vaccines available to us are reasonably safe and (surprisingly) effective at preventing disease. For people of all age groups, the risk of COVID far outweighs the risks of vaccination. As mature citizens and consumers of health care, we need to step up and take the vaccines offered to us to protect ourselves, our friends, family and society as a whole. Only through the embrace of these rapidly developed, but carefully tested, vaccines can we return to anything resembling normal in 2021.
Mark Wallace, MD | Infectious Disease Specialist
A Skagit County native, Mark Wallace, MD is an infectious disease specialist who possesses extensive training and experience in tropical medicine, including field work in the Middle East, Africa and South America. He was a clinical professor at three medical schools and published more than 200 articles in peer-reviewed literature.