Weighing the Risks and Benefits of COVID-19 Vaccination

Dartmouth-Hitchcock experts address questions about COVID-19 vaccination.

Vaccines remain the safest way—and the most effective way—to beat this virus. COVID-19 is a preventable disease at this point.

Jose R. Mercado, MD

As the COVID-19 pandemic continues, the Delta variant is mostly affecting unvaccinated people. Jose R. Mercado, MD, associate hospital epidemiologist, Dartmouth-Hitchcock Medical Center (DHMC), explains the Delta variant is about 50 percent more transmissible than the alpha variant of COVID-19. “Unvaccinated people are five times more likely to be infected and 29 times more likely to be hospitalized from COVID-19,” he says. “Outside of the acute infection, there's a 10 to 30 percent chance of any infected individual developing long-term symptoms.”

Despite high community spread of COVID-19, many have concerns about being vaccinated. These range from the U.S. Food and Drug Administration’s (FDA) emergency authorization process and vaccine safety, to their effectiveness and related side effects. A panel of DHMC experts, including Mercado, recently addressed these topics during a virtual question-and-answer event.

Understanding the vaccines

The FDA’s emergency authorization process is used to provide therapeutics during a public health emergency. DHMC Ambulatory Pharmacy Manager Marilyn Hill, PharmD, MHA, says each of the three vaccines—Pfizer, Moderna and Johnson & Johnson—were required to have at least two months of data from Phase III trials, the last trial phase before drugs are marketed. The Pfizer vaccine, which is now fully approved, has nearly two years of safety data behind it.

The panel, including Philip Adamo, MD, MPH, section chief, Occupational and Environmental Medicine, DHMC and Michael Harhen, administrative director, Pathology & Laboratory Services, DHMC, agrees that no corners were cut on COVID-19 vaccine development, and that vaccines are proven public health accomplishments for their disease-stopping and life-saving results.

The COVID-19 messenger RNA (mRNA) vaccines do not change DNA, but create immune responses. “mRNA is a very unstable molecule. We know that it can't be outside the freezer for a really long time. It can't be exposed to light,” Hill explains. “So when compared to the force of nature that is your body, you really won't expect to see any response besides what you see in the two weeks after you get that dose…it's going to be excreted from your system pretty quickly.”

Myocarditis, heart muscle inflammation, has been linked to some mRNA vaccinations. Mercado says there have been 40.6 cases per million of second doses of mRNA COVID-19 vaccines administered to males age 12-29 years. Someone who contracts COVID-19 is 16 times more likely to get myocarditis than a vaccinated person. 

The side effects of each COVID-19 vaccine are posted on the FDA website and are quite mild and short-lived: fatigue, headache and muscle aches are the most common.

Does it work?

Some who have already had COVID-19 wonder whether vaccination is necessary. Mercado says that natural infection immunity exists, but is less predictable and stable. It only lasts three to six months, while COVID-19 vaccination provides six to eight months of immunity. COVID-19 infection can occur in vaccinated people, but they are typically asymptomatic or have mild symptoms that don’t require hospitalization.

“Vaccines remain the safest way—and the most effective way—to beat this virus. COVID-19 is a preventable disease at this point,” Mercado shares. “If we don't get to where we're stopping the spread of infection, unfortunately it does mean we may continue to see variants and follow mitigations such as mask mandates.”