Understanding the Science Behind the COVID-19 Vaccine

A Dartmouth-Hitchcock expert panel discusses the science behind the COVID-19 vaccines.

The COVID-19 pandemic continues to wreak havoc on health care systems and staff nationwide as it hospitalizes unvaccinated individuals almost exclusively. While many have lingering concerns about the vaccine, data proves that it is both effective and safe.

A new United Kingdom study shows vaccination reduces the risk of developing long-term symptoms by more than 50 percent, reduces hospitalization risk by more than 60 percent and makes it twice as likely to be asymptomatic in cases of breakthrough infection, according to Jose R. Mercado, MD, associate hospital epidemiologist, Dartmouth-Hitchcock Medical Center (DHMC). “When it comes to safety, a recent study that looked at the Vaccine Adverse Event Reporting System (VAERS) showed that out of about nine million participants, only 0.1 percent develop adverse effects. And 90 percent of that 0.1 percent only really had non-serious side effects, such as dizziness and headache,” he says.

Mercado shared this data during a recent virtual question-and-answer session—the second of its kind—that detailed the science behind the vaccines. He was joined by fellow DHMC experts Philip Adamo, MD, MPH, section chief, Occupational and Environmental Medicine, Michael Harhen, administrative director, Pathology & Laboratory Services and Marilyn Hill, PharmD, MHA, manager, Ambulatory Pharmacy.

Addressing legitimate concerns

Questions continue to circulate about the U.S. Food and Drug Administration’s (FDA) emergency use authorization. Emergency use is designed for public health crises and does not mean a product has been rushed to market—but that administrative barriers have been removed to help the community-at-large, Mercado explains.

“The [DHMC] laboratory is driven by science and we're held to strict regulations. Even the commercial methods of the testing that we're using—[to] diagnose and two antibody tests that measure the immune response of a vaccine–were emergency use authorization as well,” Harhen shares. “So we're not just talking about the vaccine: even the diagnostics had emergency use authorization.”

Hill says there is no distinction between the Pfizer vaccine authorized for emergency use and the now fully approved one.

COVID-19 vaccines 101

The COVID-19 vaccines use messenger RNA (mRNA) that spike a protein the body then builds immunity against. They have no preservatives, and have all gone through the appropriate clinical trials. Contracting COVID-19—which can cause myocarditis, clots, heart attacks and stroke—is much more dangerous than the mild side effects from the vaccine.

While deaths reported after vaccination are noted by the Centers for Disease Control and Prevention (CDC) at a rate of 0.0020 percent, there are likely underlying, chronic conditions related to them. “The raw reporting itself is not where we should be concerned at this point,” Hill explains.

Vaccines also provide at least six to eight months of immunity, which does not lower to zero immune response after that time period; it wanes. This is much more reliable than natural immunity from having COVID-19.

“Eighteen months out, we are still seeing a surge, and we've tried to see whether we can have a vaccinated population versus an unvaccinated population. We haven't prevented hospitalizations, and we still have people who are at an increased risk of severe disease and death,” Mercado says. “Our best tool in ending this pandemic and moving forward to an endemic state where COVID-19 leads to just mild to asymptomatic infections is really up to us.”

To learn more about COVID-19 vaccination, talk with your health care provider and visit the CDC and FDA websites for data.