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Editor’s note: This story is part of our MC faculty and staff series in which professors and/or staff members discuss relevant topics within their areas of expertise. Dr. Glen C. McGugan is a microbiology professor at MC and Dr. Rebecca Thomas is biology chair at the Rockville Campus.

With so much misinformation about COVID-19 and vaccination making the rounds, we thought it would be appropriate to ask two of our experts to share what the scientific evidence suggests.

Why should I get vaccinated?

It is still not known exactly why COVID-19 causes such severe disease in some people, so it is impossible to predict if someone will have a mild or serious case if they become infected.

This question is perfectly reasonable if you have not yet been vaccinated against COVID-19. There are many different reasons why someone may not be vaccinated. For some, vaccination is not possible due to young age or certain health conditions. For others, getting the vaccine may not be high priority while juggling life’s many other responsibilities. Still others may have unanswered questions about the vaccine leading to increased caution or even distrust. Sadly, misinformation surrounding vaccine safety and efficacy has been spread widely, largely unchecked, on social media and is contributing to hesitancy about COVID-19 vaccination.

So, why should someone be vaccinated? If you’re asking that question, you may be wondering whether you even need the vaccine.

Myth: I Don’t Need the Vaccine

Common misconception: “I’m otherwise healthy with no underlying health conditions, and I’m not that worried about getting COVID-19. I never get the flu vaccine and rarely need to take medicine, so why should I get vaccinated against COVID-19?”

Even otherwise healthy people may become severely ill and require hospitalization

People infected with the virus that causes COVID-19 may experience a range of symptoms, from very mild (or even asymptomatic) to severe disease leading to organ damage and even death. While you are more likely to develop severe disease and require hospitalization if you are older and/or have one or more underlying health conditions, there are numerous cases of young and healthy people becoming severely ill. It is still not known exactly why COVID-19 causes such severe disease in some people, so it is impossible to predict if you will have a mild or serious case if you become infected.

Misinformation surrounding vaccine safety and efficacy has been spread widely, largely unchecked, on social media and is contributing to hesitancy about COVID-19 vaccination.

Post-acute sequelae of COVID-19 (PASC), Long COVID, Post-COVID Conditions

While COVID-19 is commonly seen as a disease primarily affecting the upper respiratory tract and lungs, it can also cause damage to many organs throughout the body. Around the world, many people who have had COVID-19 are developing a wide range of persistent symptoms lasting many weeks to months. These include fatigue, tiredness, brain fog, headaches, muscle aches, and shortness of breath. This is even seen in patients following mild infections. This is an active area of research, so it is not yet well understood who is most susceptible to it. However, it has become increasingly clear that PASC is not limited to those with previous underlying health conditions or those who have been hospitalized with COVID-19. While it is an ongoing area of research, recent studies suggest that people who are fully vaccinated are substantially less likely to develop long COVID symptoms should they become infected.

Getting vaccinated protects you and others around you

A recent CDC study demonstrated that communities with high vaccination rates had lower rates of infection in schools as compared to schools in communities with low rates of vaccination.

Each person who gets vaccinated brings us one step closer to finally ending this pandemic. Vaccination offers strong protection against COVID-19. Even after the highly contagious Delta variant became the most common variant in the United States, a CDC study suggested that fully vaccinated people had five times reduced risk of infection compared with unvaccinated people and more than 10-times reduced risk of becoming hospitalized. This adds to a growing body of evidence suggesting that people who are vaccinated are less likely to develop symptoms and have a substantially reduced risk of severe illness and death from COVID-19 compared with unvaccinated people.

While you may not be in a high-risk group, there are many people in your community whose best protection is to be surrounded by vaccinated folks. Examples include very young children for whom vaccines are not yet authorized—the FDA Advisory Committee voted in favor of authorizing the Pfizer/BioNTech vaccine for the 5 to 11-year old kids and FDA scientists and the director are set to weigh in soon but younger kids will need to wait longer—and individuals with certain health conditions, including the severely immunocompromised, who may not be able to mount a strong immune response even if they are vaccinated. Data from the CDC suggest that communities with high vaccination rates have lower rates of infection in schools as compared to schools in communities with low rates of vaccination. Another study demonstrated that emergency room visits and hospital admissions among persons aged 0-17 years were higher in states with lower vaccination coverage compared to states with higher vaccination coverage. From late June 2021 to mid-August 2021, there was a 10-fold increase in COVID-19 hospitalization in children 0 to 4 years old (who are not yet eligible for the vaccine) and 10 times higher hospitalization in unvaccinated adolescents (12 to 17 years) compared with fully vaccinated adolescents.

Common misconception: “I’ve already had COVID-19, so why do I need to be vaccinated?”

Natural infection may not confer strong or lasting protection

Natural infection can provide protection against future infection, but the strength of that protection can vary widely across individuals—and it is unknown how long that protection lasts. A recent study found that not all people recovering from COVID-19 developed virus specific antibodies, important immune system compounds that can fight future infections. However, evidence is emerging that people may get better protection by being fully vaccinated, even if they’ve been previously infected with COVID-19. According to one study suggested that those who had COVID-19, but remain unvaccinated, are more than twice as likely as fully vaccinated people to get COVID-19 again. Still other studies have demonstrated that vaccination after having COVID-19 provides a huge boost in protection.

Vaccines are rigorously tested for safety, which is impossible to do for natural infection. Since there is no way to predict exactly how a natural infection may affect you, vaccination is a much safer option for building robust immunity.

Myth: I Don’t Trust the Vaccines

Common misconception: “The vaccines are experimental, and they were developed too quickly.”

Vaccine development historically has been a multi-year process, so the rapid development of the currently available vaccines has made some wonder if there were any corners cut in the process. How were they developed so quickly?

Years of Previous Research

For COVID-19, the federal government provided unprecedented funding to vaccine developers, which allowed acceleration of the timeline. Even so, no safety corners were cut in the process.

While SARS-CoV-2 is a new virus, scientists had been studying other coronaviruses for many years, including those causing SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Because of this research, a great deal of important information was already known,  including knowledge about good targets for vaccine development. Researchers have also been working on and developing mRNA vaccines for over 10 years, including some for use in cancer therapy. The mRNA vaccine platform allows for more rapid development and manufacturing compared with other types of vaccines. After the SARS-CoV-2 genetic sequence was available, parts of this sequence were plugged into the preexisting mRNA technology, and it took just a few days to make the mRNA vaccine candidates for testing.

Safety First

The testing phase of vaccine development often takes many years due to its tremendous cost. For COVID-19, the federal government provided unprecedented funding to vaccine developers, which allowed acceleration of the timeline. Even so, no safety corners were cut in the process. Before any clinical trial begins, a data and safety monitoring board approves the study protocol. The companies must follow a strict process for potential vaccine approval including applying to the FDA (Investigational New Drug), conducting clinical trials, inspection of the manufacturing facility and presentation to FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC). Members of this committee are experts from around the country with a range of vaccine related expertise. Importantly, these scientists and physicians are not FDA employees and the discussion is open to be viewed by the public. The FDA then carefully reviews data from each clinical trial phase and considers the recommendations from the VRBPAC before approval. Following the rigorous approval process, the FDA continues to oversee production to ensure continuing safety and any potential side effects continue to be monitored by the FDA and the CDC.

See also this interactive tool comparing a typical and accelerated timeline for vaccine research and development.

Common misconception: “The vaccines may change my DNA and even make me infertile”

mRNA vaccines cannot change your DNA

Based on decades of experience with other vaccines, any potential serious side effects occur early – from a few minutes to about six weeks after vaccination. Based on this, the FDA required each of the available COVID-19 vaccines to be studied for at least two months following the final dose prior to authorization.

Pfizer/BioNTech and Moderna vaccines use an mRNA vaccine platform. Messenger RNA (mRNA) is a normal biological molecule found in your cells. Your cells use mRNA as a blueprint to build proteins inside your cells. For a vaccine (and even a virus) to interact with or change your DNA, at least two things must occur. First, since your DNA is enclosed in a membrane-bound nucleus, the mRNA must be able to get inside your nucleus and be converted into DNA. This requires an enzyme known as reverse transcriptase. Some viruses, such as HIV, have this enzyme. However, the mRNA vaccines do not. Secondly, even if the mRNA were to be made into DNA, it still must be able to be integrated into your cellular DNA. This requires a second enzyme known as integrase, which the mRNA vaccines also do not contain. Fortunately, it is not biologically possible for the mRNA vaccines to alter your DNA.

COVID-19 vaccines do not cause fertility problems

There is currently no evidence showing that any vaccine, including COVID-19 vaccines, cause fertility problems in men or women. Pregnant women are often excluded from initial clinical trials as an extra precaution. However, even with the clinical trials for the mRNA vaccines, some became pregnant after having received the vaccine. Further, with hundreds of millions of vaccine doses now administered, there are numerous examples of successful pregnancy after vaccination. The American Society of Reproductive Medicine, American College of Obstetricians and Gynecologists, and the Society for Maternal-Fetal Medicine have all issued statements that they find no evidence of infertility linked to vaccinations.

Importantly, the CDC issued an urgent health advisory when emerging data suggested that pregnant people with symptomatic COVID-19 have a 70% increased risk of death.

There have also been studies in men including one demonstrating that healthy men who received an mRNA COVID-19 vaccine had no significant change in sperm characteristics (semen volume, sperm concentration and motility and total sperm count) following vaccination, suggesting no effect on fertility.

Common misconception: “The vaccines may cause long-term harmful effects that we might not know for years”

We’ve all heard stories of medications being pulled from the market for side effects that showed up years later. So, how are experts so confident in the long-term safety of the COVID-19 vaccines? How can we be sure that scientists will not discover rare problems caused by these vaccines in the years ahead?

Medicines vs. vaccines

First, there are important differences to consider between medicines and vaccines. Medicines may be taken daily for several days or even several years and may cause side effects that are only obvious as levels of the drug build up in a person’s body over time. However, vaccines are administered only once or a handful of times throughout a person’s life. They are designed to deliver cargo and are then quickly eliminated from the body. As a result, serious side effects that could cause long-term health problems are extremely unlikely for any vaccination, including COVID-19 vaccines.

Vaccine side effects occur early

The level of virus decreases faster in vaccinated people suggesting that they are likely infectious for a much shorter period as compared to unvaccinated.

Based on decades of experience with other vaccines, any potential serious side effects occur early – from a few minutes to about six weeks after vaccination. Based on this, the FDA required each of the available COVID-19 vaccines to be studied for at least two months following the final dose prior to authorization. Potential side effects reported during the clinical trials mostly consisted of arm pain, fatigue and headaches that occurred the first couple of days after vaccination and then resolved quickly. Vaccine safety has been continuously monitored and the vaccines have been administered to hundreds of millions of people. A few serious side effects have been found, but these have all been extremely rare, occurred within the first few minutes to few weeks following vaccination, and are treatable. No long-term side effects have been detected.

While all vaccines and medications carry some level of risk for potential side effects, the benefit of COVID-19 vaccines far outweighs known and potential side effects, which have been temporary and mostly mild.

Common misconception: “The vaccines are not working. I’ve heard of many people still getting infected even after they were vaccinated—and vaccinated people are just as likely to transmit the infection as unvaccinated. So, why should I get vaccinated?”

The vaccines remain effective at preventing infection and even incredibly effective at preventing severe disease, hospitalization, and death.

So, how is it that some vaccinated people are having “breakthrough” infections?

Early on, vaccines more effective against infection

First, it’s important to note that while these vaccines are extraordinarily effective, no vaccine is 100% effective. During the clinical trials for these vaccines, researchers measured the efficacy of the vaccine at preventing symptomatic disease, hospitalization, and death rather than routinely testing for any infection at all. However, in the first few months after the vaccines were authorized and rolled out more broadly, it became clear that they were also incredibly effective at preventing infection as documented by PCR testing.

So, what changed?

The human immune system

To answer this, it’s useful to know a bit about how the human immune system functions. When we receive a COVID-19 vaccine, specialized cells of our immune system are exposed to the spike protein from the virus that causes COVID-19, recognize it as something foreign, and are primed into action to produce loads of antibodies and specialized cells capable of attacking virus-infected cells. (Note: during this phase, the immune system ramps into action just as if we had an actual infection, which is why some people can have mild symptoms like arm pain, headache, and fever – see section above on vaccine side effects). The spike protein is used by the virus to enter our cells, so antibodies that can bind this protein can block the virus from being able to infect our cells (neutralizing antibodies). These antibodies flood our system after vaccination (and natural infection), but the circulating levels decay over time. This is completely normal, though. Why? Imagine if our bodies kept this extraordinary level of antibodies flooding our system for every infection we’ve ever had throughout our lives? Our blood would be like sludge from all the extra protein! Thankfully, our bodies have a backup plan through special types of memory cells that remain to ramp into action should we be faced with the actual virus.

The levels of circulating neutralizing antibodies tend to decrease over time following vaccination. If we are exposed to someone who has COVID-19, this means there may not be enough to block all viruses from entering our cells. However, we are still highly protected against severe disease, hospitalization, and death even if we become infected after vaccination.

The mRNA vaccine platform allows for more rapid development and manufacturing compared with other types of vaccines.

Delta variant

The vaccine clinical trials and studies shortly after vaccine rollout were done in the presence of the original strain of the virus. Since then, several viral variants have emerged, including those far more contagious and capable of causing more severe disease. Since July 2021, the Delta variant has been predominant, now accounting for greater than 99% of circulating variants in the country. The Delta variant is highly contagious – more than twice as contagious as previous variants, and far more contagious than the original strain of the virus. In communities where there are high rates of viral transmission, even vaccinated people are more likely to encounter the highly contagious Delta variant and become infected.

Fully vaccinated can spread the virus, but for a shorter time

With breakthrough infections from previous variants of the virus, lower amounts of viral material were found in samples taken from fully vaccinated people. For the Delta variant, similar levels of viral material have been found in samples from unvaccinated people and vaccinated with breakthrough infections. However, as with previous variants, the level of virus decreases faster in vaccinated people suggesting that they are likely infectious for a much shorter period as compared to unvaccinated.

Common misconception: “I heard ivermectin is effective and safer than the vaccines. So, I’d prefer to take it if I get infected.”

The FDA has not authorized or approved ivermectin for use in preventing or treating COVID-19 in humans or animals. Ivermectin is approved for human use to treat infections caused by some parasitic worms and head lice and skin conditions like rosacea.

Ivermectin is an FDA-approved antiparasitic drug that is used to treat diseases including onchocerciasis, helminthiases, and scabies. While it is widely used and generally well tolerated, it is not approved by the FDA for the treatment of any viral infections. Importantly, animal formulations of the drug can be extremely toxic in humans and should not be taken. The results of several trials and retrospective cohort studies have been reported. Some studies show no benefits or even worsening of the disease after use of ivermectin, while others showed some benefit. However, these studies had incomplete information and significant limitations. The NIH COVID-19 Treatment Guidelines Panel, the Infectious Disease Society of America, the American Medical Association, and other such panels have all concluded that there is insufficient evidence to recommend the use of ivermectin for the treatment or prevention of COVID-19.

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