Although the federal public health emergency ended in 2023, COVID-19 continues to evolve and affect health worldwide. The virus remains part of our daily lives and still poses risks, especially for people vulnerable to severe illness. Vaccination remains a key tool for protecting individuals and communities, much like with influenza.
In the following Q&A, experts Marian Jarlenski, PhD, professor and vice chair for practice in health policy and management, and Donald S. Burke, MD, dean emeritus, address common questions about why continued vaccination matters, how boosters work, and what the latest evidence says about safety and effectiveness, including during pregnancy and breastfeeding.
What ongoing risks make continued COVID vaccination important, even years into the pandemic?
Jarlenski: We are all relieved to be past the COVID emergencies that closed schools and businesses in 2020. But even though that phase is over, COVID remains with us as an endemic respiratory virus. Like flu, it will continue to mutate and pose risks for severe infection and death.
We often think about healthcare decisions as personal choices. But vaccines work differently, because my vaccination status affects the risk for those around me. The more people vaccinated, the slower a virus spreads, and the better protected vulnerable people are. When coverage is high—above 95%—diseases can even disappear, as happened with polio in the U.S.
That’s why routine annual vaccination for viruses like COVID and flu is recommended to protect communities.
How does waning immunity and the emergence of new variants shape the need for updated boosters?
Burke: After vaccination, protective antibodies peak within weeks but then wane, so by six months, protection against infection is low. Annual boosters keep antibody levels high. New variants can sometimes evade protection, so ideally boosters are updated to match circulating strains.
What evidence shows that vaccination continues to reduce severe outcomes, even for people who have had prior infection?
Burke: Several studies in top medical journals show that people with prior infection who are also vaccinated—what’s called “hybrid immunity”—have stronger protection than those with infection alone.
What monitoring systems are in place to track the safety of vaccines?
Burke: The U.S. has several complementary systems. VAERS (Vaccine Adverse Event Reporting System) is a large passive system where anyone can report a possible safety issue. Other systems actively track health outcomes, such as CDC’s Vaccine Safety Datalink, which uses electronic health records, and FDA’s collaboration with Medicare, which links vaccination data with health claims.
Is COVID-19 vaccination safe during pregnancy?
Jarlenski: Yes. Large studies—including one analyzing data from more than 17 million pregnant women—show that COVID-19 vaccination is safe in pregnancy.
Does timing of vaccination during pregnancy affect safety or effectiveness?
Jarlenski: Vaccination early in pregnancy is generally recommended. The good news is that it can be given at the same time as other routine vaccines in pregnancy, such as flu, which makes it convenient during prenatal visits.
How effective are vaccines in protecting pregnant individuals from severe illness?
Jarlenski: Pregnant individuals face higher risks of severe COVID due to normal physiologic changes, like added stress on the respiratory system. Vaccination has been shown to prevent severe disease and hospitalization, which is why it’s strongly recommended during pregnancy.
Do vaccinated pregnant people pass antibodies to their babies?
Jarlenski: An important benefit is that antibodies from vaccination are transferred before birth, which can protect the newborn. Studies show this protection is stronger with vaccination than with infection alone. Vaccination during pregnancy helps shield newborns during their first months of life. Because maternal antibodies protect infants, vaccination during pregnancy lowers the risk of hospitalization from COVID-19 in newborns.
Is breastfeeding safe after vaccination and do antibodies in breast milk protect infants?
Jarlenski: COVID-19 vaccination is both safe and beneficial for those who are breastfeeding. Research shows that maternal antibodies from vaccination are passed through breast milk and help protect infants from severe infection. The vaccine’s mRNA itself does not pass into breast milk, only the antibodies that the parent’s immune system makes after vaccination. Those antibodies can help protect the infant.
Pitt employees and their family members (ages 12 and older) who wish to receive a COVID-19 vaccination should schedule an appointment at the Pitt Vaccination & Health Connection Hub. The 2025–26 Pfizer and Moderna adult vaccines are available now, and pediatric doses have been pre-ordered for future availability.
-Clare Collins