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Two COVID-19 vaccines are now being used in the United States, fueling hope that the global pandemic will soon shift to a better-controlled phase. Here, Stanford Children’s Health pediatric infectious disease expert Roshni Mathew, MD, explains what the news means for immunization of children and pregnant women and debunks myths about the vaccines.

Q. Can the vaccines give you COVID-19?

Dr. Mathew: No. None of the COVID-19 vaccines in development or in use in the U.S. are live vaccines. The vaccines cause the body to recognize the virus protein so the immune system can develop a response to it. 

Q. Could the COVID-19 vaccine make you more susceptible to other illnesses or dampen the function of your immune system?

Dr. Mathew: COVID-19 vaccines allow the immune system to recognize the SARS-CoV-2 virus and mount a response to it. The vaccine does not cause one to be more susceptible to other illnesses. Our immune system is capable of recognizing and protecting us from many different pathogens simultaneously.

Q. Will the COVID-19 vaccine be made mandatory?

Dr. Mathew: As of late January, two COVID-19 vaccines have received an emergency use authorization from the Food and Drug Administration (FDA), which allows their use in a limited fashion as directed by the FDA and the Centers of Disease Control and Prevention (CDC). In these situations, use of the product cannot be made mandatory. There could, however, be local and institutional vaccination requirements, such as for employees in health care or other front-line jobs.

Q. How was it possible to make an effective vaccine in such a short time?

Dr. Mathew: Developing a new vaccine typically takes several years; the mumps vaccine, which took four years to develop, was the fastest until now. In case of COVID-19 vaccines, several steps that typically occur in sequence happened in parallel. In addition, several pharmaceutical and academic establishments worked toward developing a vaccine independently. The safety and efficacy safeguards, however, are all still in place, as for any other vaccine. The COVID-19 vaccines now in use have met the required safety and efficacy thresholds.

Q. Will the COVID-19 vaccines stop the pandemic?

Dr. Mathew: Vaccination is one strategy to reduce burden of COVID-19 disease. Since the vaccines are not 100% efficacious, other measures to reduce transmission — such as social distancing, frequent handwashing, and wearing masks in public — will need to continue until a substantial number of people are vaccinated. The vaccine trials showed that the vaccines protect very well against symptomatic COVID-19 disease. We don’t yet know if they also prevent asymptomatic infection or viral transmission. The CDC will continue to closely monitor the response to vaccination and infection rates as more people are vaccinated to provide advice on when we can safely move away from other control measures.

Q. When will children be able to receive COVID-19 vaccines, and what research is still needed before that can happen?

Dr. Mathew: Some of the vaccine trials are including children older than 12 years in the US. Outside these trials, children are not currently receiving vaccines. However, as we get more information from the trials, the FDA and CDC will weigh in on when children can safely receive the vaccines.  

Q. Are pregnant women at higher risk for COVID-19 illness, and what are the plans for vaccinating them?

Dr. Mathew: Although there is more to learn, studies so far raise concerns that pregnant women are at increased risk for severe illness from COVID-19. Although pregnant women were not enrolled in the trials, there were women participating who became pregnant during the course of the trial, and so some information will be available on them in the future. The CDC and the American College of Obstetricians and Gynecologists recommend that vaccines not be withheld from pregnant and lactating women. Pregnant women eligible for vaccination who have questions should discuss the risks and benefits with their obstetrician.

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