COVID-19 Vaccine FAQ

COVID-19 Vaccine FAQ

With the first COVID-19 vaccines now being administered to health care workers in Tennessee, Le Bonheur Division Chief of Pediatric Infectious Diseases Dr. Sandy Arnold answers frequently asked questions we’ve received about the vaccines themselves and what this latest development in the fight against the novel coronavirus pandemic means for families.

Q: Is there a COVID-19 vaccine available for children?

The preliminary results from the Pfizer-BioNTech vaccine study used to issue the Emergency Use Authorization included children aged 16 years and older. There were only 156 16-and 17-year-olds included in the study, which means there is limited data in this age group. The Moderna vaccine did not enroll anyone younger than 18 years old. These vaccines will be available for children at a later date.

There will be studies in children to determine the optimal dose of vaccine (to minimize the side effects like arm pain and fever/malaise) and maximize availability of doses (the less you have to use to vaccinate, the more doses available overall). The Pfizer study is still enrolling down to age 12 currently.

Pfizer-BioNTech is planning to have combined Phase 1, 2 and 3 studies for children 5 to 18 years of age underway next summer. Le Bonheur/UTHSC hope to be a site for that study.

Moderna is planning to first study 12-17 year olds and will likely have studies in younger children. It is not clear why these companies have waited to initiate studies in children and many advocacy groups, like the American Academy of Pediatrics, have spoken out about this delay. That said, the reasons for vaccinating children would be more about protecting others, since severe infection due to COVID-19 in children is rare. Given limited vaccine supply, children likely would not be vaccinated until later in 2021.

Q: What is the difference between the two available vaccines?

These first two COVID-19 vaccines (there are many others still in the pipeline that are quite different) are both mRNA vaccines. This is a new vaccine platform and there are no other vaccines of this kind currently in use.

COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece protein called the spike protein. The spike protein is found on the surface of the virus that causes COVID-19 and is what the virus uses to gain access to our cells and cause infection. However, on its own, it cannot cause COVID-19.

COVID-19 mRNA vaccines are given in the upper arm muscle. Once the instructions (mRNA) are inside the immune cells, the cells use them to make the protein piece. Even though the mRNA is a form of genetic material, like DNA, it is not DNA. It cannot get into the part of the cell where the DNA lives (the nucleus) and cannot become a part of the DNA. After the protein piece is made, the cell breaks down the instructions and gets rid of them.

Next, the cell displays the protein piece on its surface. Our immune systems recognize that the protein doesn’t belong there and begin building an immune response and making antibodies, like what happens in natural infection against COVID-19.

At the end of the process, our bodies have learned how to protect against future infection. The benefit of mRNA vaccines, like all vaccines, is those vaccinated are protected without ever having to risk the serious consequences of getting sick with COVID-19.

The main differences between the two vaccines currently available are the storage requirements and the duration of time between doses (21 days for Pfizer-BioNTech and 28 days for Moderna). Both vaccines generated a similar level of protection in the study participants.

Q:  Are there any side-effects?

Both vaccines commonly cause pain at the injection site. After the second dose, there may be more pain and also some systemic effects like fever, fatigue and muscle aches. These side effects are short-lived -- around 1-2 days on average. These are very similar to the side effects of other routine vaccines.

Q: Why two shots?

Early studies showed that two doses were needed to produce strong and long-lasting responses. This is not unusual with vaccines, especially if you have never been infected with the virus.  For example, for influenza (flu) vaccines, if you are under nine-years-old when you get your first flu shot, you need to get two doses, one month apart. If you are over age nine, it is assumed you have been infected with the flu before and that you will boost your immunity sufficiently with a single shot. 

Q: How can we tell that the vaccine is working?

There is no way to actually see that it is working. Outcome data shows that the vast majority of people will not get sick when exposed to virus after receiving two doses.  

Q: Are these vaccines safe for immune-compromised people?

These two vaccines are definitely safe for people who are immunocompromised (people whose immune systems are not strong enough to fight off infection) because the vaccine does not contain live virus. Only live virus vaccines are unsafe in those with compromised immune systems. The issue is whether immunocompromised individuals can respond well to any vaccine and have a good immune response that protects them from the disease.

The studies did not include people with immunocompromising conditions or on immunocompromising drugs, except for stable HIV infection, so we don’t yet know how well these individuals will respond. However, some response is better than none and so immunocompromised people should be vaccinated. We will have to wait until a lot of people are vaccinated before immunocompromised individuals can relax their precautions, like everyone else.

 Q: Will people have to continue to wear masks?

Yes, people will have to continue to wear masks for a while. The two authorized vaccines have not been studied to determine if the vaccines completely prevent infection or if they simply prevent symptomatic infection. This means we don’t know whether vaccinated people can become infected and spread the virus even though they themselves do not become sick. More information will come when more people are vaccinated and will help answer that question.

Q: How long before we see a significant difference in everyday life?

We probably need to see a substantial portion, maybe 40 or 50 percent, of people vaccinated before we see reductions in spread of virus without other interventions (increased adherence to mask wearing and social distancing). Some experts have said that for substantial virus suppression we might need 75 percent of people vaccinated.

In short, no one really knows what proportion of the population needs to be vaccinated to achieve herd immunity (when enough of the population is immune to prevent spread of the virus) and what herd immunity will actually look like. And we are not just talking about vaccinations for people in the United States. We will need to have a large proportion of the world’s population be vaccinated as travel is common. Since we do not know whether vaccinated people can still spread virus, it is very difficult to determine how many people will need to be vaccinated to get to the point where our lives start to look more normal. That said, getting everyone vaccinated is the only way we are going to get back to normal.

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