Coronavirus mailbag: Responding to your COVID-19 vaccine concerns

Vaccine, pregnancy

(Unai Huizi Photography, Shutterstock)

Editor's note: These answers are based on interviews and information current as of the time of publication.

SALT LAKE CITY — We asked unvaccinated readers to tell us why they haven't been vaccinated, and 3,807 people responded. We analyzed the multiple-choice questions and reported the trends, but we also received over 1,000 write-in responses with individual questions and concerns that formed common threads.

Over 27% of respondents (1,036 people) who answered our question "why haven't you been vaccinated for COVID-19?" wrote individual responses explaining their personal decisions.

Here are some of the common concerns people had, as well as some of the most recent scientific explanations about the topics.


Are natural antibodies stronger than the vaccine or comparable to it?

One of the most common reasons people opt out of receiving the vaccine is the belief that natural antibodies after being infected with COVID-19 are superior or comparable to the vaccinations.

A study from the National Cancer Institute suggests that natural COVID-19 antibodies do provide moderate protection against the virus and reduce the likelihood and severity of reinfection, but it's not as strong as the vaccinations.

Similarly, a study from Stanford University found that people with asymptomatic and mild cases of COVID-19 have lower levels of antibodies than people with severe cases, and that all antibodies wane after 90 days. The Centers for Disease Control and Prevention says that some people who had COVID-19 never test positive for antibodies.

By contrast, early findings from the New England Journal of Medicine comparing those who have received the Moderna vaccine and those who have recovered from COVID-19 showed that vaccinated people had higher levels of antibody protection. Another study from the New England Journal of Medicine found that immunity provided by vaccination lasts for a minimum of six months.

When vaccines were limited, health officials suggested those who already had COVID-19 wait 90 days before being vaccinated. Now with increased vaccine supply, the 90-day wait period only applies to those who were treated with monoclonal antibodies or convalescent plasma, the CDC says.

How do we know the COVID-19 vaccines didn't cut corners?

One of the most common write-in responses we received was from people who felt they wanted more time to pass in order for them to know that the vaccines are safe. Some wanted full FDA approval; some wanted longitudinal studies; and some felt that the vaccine was rushed.

In order to receive FDA emergency approval, vaccines must pass phase one, phase two and phase three trials with predetermined success levels. Normally, this process takes years, and mass manufacturing takes at least an additional six months.

Phase one trials include inoculating a small number of healthy people to test their immune responses. Phase two studies include more people across various ages, demographics, and health statuses who receive various vaccine doses. Phase three includes thousands of people from various backgrounds who represent the population the vaccine is meant for.

Due to the severe nature of the pandemic, the federal government created Operation Warp Speed, which partnered with trusted vaccine manufacturers and limited research to the vaccine technology that was most likely to produce safe and effective vaccines. As the New England Journal of Medicine New England Journal of Medicine explains, the U.S. government purchased hundreds of millions of COVID-19 vaccines at the same time the trials were conducted so that once vaccine safety and efficacy were confirmed, shots could begin without months of manufacturing and raw materials delays.

The Pfizer-BioNTech, Moderna and Johnson & Johnson vaccines all completed and passed their phase one, two, and three trials before they applied for FDA emergency approval.

What's the difference between emergency approval and full FDA approval?

Pfizer-BioNTech and Moderna have both applied for full FDA approval, which usually takes a year. FDA Commissioner Dr. Robert Califf told CNBC that in addition to the ongoing review of health data, the full approval process includes negotiations between the government and vaccine companies about product labeling, manufacturing and marketing. Emergency use authorization doesn't permit advertising for products, but full authorization does, he said.

According to the director of the World Health Organization, the vaccines are "highly likely" to receive full approval and the process may conclude as early as the second half of this year.

If the vaccine has only existed for one year, how do we know it won't have long-term negative effects?

While the COVID-19 vaccine has only existed for a year, vaccine research dates back over at least 80 years. Historically, severe side effects from vaccines are extremely rare and usually show up by the first two weeks, University of Michigan Health Care explains. At most, the side effects show up within the first two months.

There's no historical precedent for a vaccine that gives people long-term side effects that appear months or years after the jab.

The Pfizer-BioNTech and Moderna vaccines are mRNA vaccines, meaning that they use the body's mRNA to provide the immune system a message (hence "messenger RNA") about how to fight COVID-19. While the COVID-19 vaccine is the first mRNA vaccine, the CDC says that scientists have studied and worked with this technology for decades, including with Zika, rabies and flu vaccines.

The J&J vaccine is an adenovector vaccine, which uses a modified version of a different virus to teach the body how to fight COVID-19. The virus cannot replicate or cause illness, and adenovector vaccines have been used since the 1970s for Zika, influenza and HIV.

While the virus is new, the vaccine technology is not.

What do we know about COVID-19 and its vaccine for pregnant people?

The most common write-in response we received from people who would otherwise be vaccinated was from pregnant people who were concerned about the safety of the vaccine for them.

According to the CDC, pregnant people are at increased risk of severe illness or death compared to nonpregnant people if they test positive for COVID-19. The virus also increases the chances of preterm labor.

There's limited but growing data about how vaccines affect pregnant people.

Trials conducted on the vaccines did not include pregnant people, though some trial recipients inadvertently became pregnant and received the vaccine, Harvard Health says. The CDC is tracking over 30,000 willing vaccine recipients who were pregnant at the time they were vaccinated, and over 1,800 have provided detailed notes of their vaccine side effects and pregnancy outcomes. So far, side effects have been the same among pregnant and nonpregnant people, and no miscarriages, stillbirths, or preterm births linked to the vaccine have been reported.


All of the approved vaccines have also been tested on animals before and during pregnancy, and no safety concerns in mothers or babies have been found, the CDC says.

Vaccines, in general, are safe and many are recommended for pregnant people. Additional trials among pregnant people who receive the COVID-19 vaccine are underway.

COVID-19 vaccinations are available for pregnant people who choose to get vaccinated, and the CDC says that a conversation with a doctor prior to vaccination may be helpful but not required. If you are pregnant and have chosen to be vaccinated, consider enrolling in the CDC's voluntary v-safe registry, which helps substantiate the safety or side effects of the vaccine.

There's also little data among people who are breastfeeding or seeking to become pregnant, but the CDC says that there is no evidence that any vaccines affect fertility and, based upon how vaccines work in the body, risks are highly unlikely.

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