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HSOP infectious disease experts explain COVID-19 vaccines, safety, herd immunity

February 4, 2021

AUBURN, Alabama - More than a year into the worldwide COVID-19 pandemic, vaccines from various pharmaceutical companies are making their ways to hospitals, pharmacies, clinics, health departments and other points of care. With the arrival of the much-anticipated vaccines comes questions on what it is, what it does and how it affects people.

Marilyn Bulloch and Spencer Durham, infectious disease experts in Auburn University’s Harrison School of Pharmacy, are on the front lines of the vaccination effort. Based on their clinical experience dealing with the virus and the vaccine, the pair attempts to educate those they encounter and ease concerns about the process.

The two primary vaccines being distributed are from Moderna and Pfizer, with both using messenger RNA, or mRNA, technology. While most people may think mRNA is new, it is actually a tried and tested technology that has been in use for more than 30 years. It is not commonly used because of the costs involved and logistics in the need for sub-zero freezers. Vaccines that use mRNA are coded in a manner to instruct the body how to generate an immune response to a particular virus.

“The vaccines use mRNA coded with information from the SARS-CoV-2 virus to instruct the body how to respond,” said Bulloch. “It does not actually have the virus. It would be like sending an email with instructions on how to build something, and once it’s built, the email is deleted.”

The use of mRNA can be seen in combatting other viruses, such as Zika, as well as non-infectious diseases like cancer. In the case of vaccines that utilize mRNA technology, the mRNA tells the body how to make a specific part of a virus, and then the immune system learns to recognize that piece of the virus and then develop antibodies to it. For COVID-19 specifically, the mRNA portion utilized is part of the spike protein on the virus, which is what allows it to infect cells.

“One of the advantages of applying this technology to vaccines is that it allows us to create vaccines much more quickly than traditional ways,” said Durham. “Most vaccines require the viruses to be grown in the lab, and then the viruses are used to create the vaccines. This is a time-consuming process, and mRNA technology allows for it to be done much faster because it does not require the actual virus.”

Both current COVID vaccines require two doses. The Pfizer vaccine is given 21 days after the first dose, while the Moderna vaccine is given 28 days after the first dose. The vaccines require two doses because the first dose gives the immune system a chance to start learning how to make antibodies to the virus, while the second helps the immune system to create long-term antibodies. While the vaccines utilize similar technologies, people should not attempt to mix-and-match the vaccines.

“In clinical trials, both have been shown to be very safe and 95% effective in preventing COVID-19 infection, which is excellent efficacy for a vaccine,” said Durham.

As with any vaccine, the potential exists for side effects or some kind of negative reaction. While there have been some reports of allergic or other types of reactions, most have been resolved within a day, with the most common being a sore arm or headache.

“We have not yet determined if there are pre-existing conditions that complicate it, but we are being cautious with patients with a history or vaccine or medication allergies,” said Bulloch. “Regardless, everyone is monitored for 15 minutes after the shot to make sure they do not have anaphylaxis or any other reactions.”

Bringing the vaccine to market was a monumental task, considering the period of time. While some may see the quick approval of the vaccine as concerning, it is actually the product of collaborative work and coordination between the government and pharmaceutical companies to remove many of the barriers typically in place to bring a drug to market.

“The safety and efficacy studies of the vaccines were not compromised in any way. When we make decisions in medicine, we always look at the risk verses benefit,” said Durham. “One common worry I hear from people is that they are worried there might be long-term side effects from the vaccine. While we cannot say with 100% certainty that there will not be, all of the current evidence points to the vaccines being extremely safe.”

Based on data from the Food and Drug Administration, or FDA, Bulloch agrees and is confident in the lack of long-term effects from the vaccines.

“The mRNA technology is 30 years old, and the companies did a good job with their studies,” said Bulloch. “The companies did a two-month safety follow-up period. The FDA keeps a database of serious vaccine reactions, and it seems that with all of the other vaccines that people receive throughout their lives, when serious reactions have occurred, they have occurred within that first two-month time window.

“It would be reasonable to expect the same from the mRNA vaccines. This makes me feel good about the timeframe in which the vaccines were studied and the long-term effects at this point.”

With most people ready to get back to their normal way of life, Bulloch and Durham agree the path to that goal is through herd immunity of the virus, meaning a majority of the population is immune, and thus the virus cannot spread as efficiently. Typically, this can be achieved by allowing people to become infected or through vaccination. With the deadly and damaging effects of COVID, vaccination is the path to normalcy.

“This virus seems to cause more trouble in patients with certain characteristics like age, obesity, diabetes and heart disease, but I have seen young, healthy people succumb to the virus as well,” said Bulloch. “While most recover, that does not mean they are not left with long-term complications from COVID-19. Being able to prevent the virus is important, but preventing long-term complications is essential too.”

Vaccine distribution is being managed by state and local health departments, with the vaccine being offered largely free of charge. Phases of distribution are in place, depending on age, health and other risk factors. Those interested in obtaining a vaccine should contact their local health department for more information.

Frequently Asked Questions:

What are the vaccines, and how are they taken?
There are two vaccines currently on the market, one from Pfizer and the other from Moderna. They are similar vaccines that are both 95% effective in preventing COVID-19 infection. They are given in two doses, ranging from 21 days to 28 days apart. People should not mix-and-match the vaccines, as that may affect the effectiveness.

Why does the vaccine come in two doses?
Both the Pfizer and Moderna vaccines require two doses because the first dose gives the immune system a chance to start learning how to make antibodies to the virus, and the second helps the immune system create long-term antibodies.

Are the vaccines safe?
The Food and Drug Administration carefully reviews all safety data from clinical trials and authorizes emergency vaccine use only when the expected benefits outweigh potential risks. The mRNA technology used in the vaccine has been in practice for more than 30 years and is a proven therapy when it comes to treating viruses and other diseases.

What are the side effects?
The most common side effects are a sore arm and other mild symptoms, such as fever, tiredness or muscle aches. These side effects usually only last 24-48 hours. The side effects may be more common after the second dose compared to the first. Neither vaccine can give anyone COVID-19, and the side effects are a sign the immune system is working to make antibodies against the disease.

Why should I get the vaccine?
The best way to fight this pandemic and return to some level of normalcy is to achieve herd immunity. There are two basic ways to achieve herd immunity: by allowing people to become infected with the disease, or through vaccination. In the case of COVID-19, it is much too dangerous to allow people to become infected because there are significant complications, including death, associated with the disease. Therefore, vaccination is our best means of achieving herd immunity and getting back to normal.


About the Harrison School of Pharmacy

Auburn University’s Harrison School of Pharmacy is ranked among the top 25 percent of all pharmacy schools in the United States, according to U.S. News & World Report. Fully accredited by the Accreditation Council for Pharmacy Education (ACPE), the School offers doctoral degrees in pharmacy (Pharm.D.) and pharmaceutical sciences (Ph.D.) while also offering a master’s in pharmaceutical sciences. The School's commitment to world-class scholarship and interdisciplinary research speaks to Auburn's overarching Carnegie R1 designation that places Auburn among the top 100 doctoral research universities in the nation. For more information about the School, please call 334.844.8348 or visit http://pharmacy.auburn.edu.

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Last Updated: April 09, 2021