Vaccines have been heralded as a key measure to slow the COVID-19 pandemic and bring it to an end. Every day, millions of American adults receive one of the licensed vaccines that have been shown to be very effective in preventing serious illnesses that could otherwise lead to hospitalizations and death. In the United States, most people over 65 have now been fully immunized, protecting the most vulnerable of our population.
As an infectious disease specialist, my answers to the questions below are based on what we know so far about infection and vaccines in children and adolescents. We will need to continue to fill in the gaps as research is done and our understanding evolves.
What do we know about how COVID-19 affects children and adolescents?
Most COVID-19 infections in children are mild or do not cause obvious symptoms. However, a small percentage of infected children
- develop a serious inflammatory disease called MIS-C within two to six weeks of being infected with COVID-19. This can happen even in children who have mild symptoms or no symptoms.
- become seriously ill and require hospitalization or intensive care.
More than 400 children have died from COVID-19 infection. That’s more than the number of child deaths during the deadliest flu season in the past two decades.
Vaccinating children to avoid these results is one of the most important reasons for vaccine studies in children. In addition, childhood immunization will be key to achieving a population-wide level of immunity – herd immunity – sufficient to slow the emergence of dangerous variants and end the pandemic.
What do we know so far about COVID-19 vaccines in adolescents?
- The Pfizer / BioNTech vaccine is approved for people 16 years of age and older.
- Moderna and Johnson & Johnson vaccines are approved for people 18 years of age and older.
- These approvals were based on data from participants of these ages in randomized, placebo-controlled trials that demonstrated the safety and efficacy of these vaccines. Efficacy measures the effectiveness of a vaccine under the controlled circumstances of a study. Efficacy is the effectiveness of a vaccine outside of a study, when community members receive it.
As states expand their eligibility for COVID-19 vaccines, teens 16 and older can receive the appropriate vaccine through the same sources that adults have had access to so far. The available vaccination sites may vary depending on the state and location where you receive health care. See the map available on VaccineFinder or your national board of health.
Vaccine research done to date or underway includes the following:
- Pfizer / BioNTech has completed a trial in 12-15 year olds. This trial used the same dose and vaccine schedule as used in adults: two doses given three weeks apart. The company announced in a press release that the vaccine was safe and well tolerated, elicited strong antibody responses, and was 100% effective in preventing mild to severe infections in this age group. The FDA is reviewing the data and will consider allowing this vaccine for use in this age group. If all goes well, we can expect this vaccine to be available for 12 to 15 year olds in the coming months.
- Moderna completed the recruitment of 12 to 17 year olds in a similar trial using the same dose and regimen as in adults: two doses given four weeks apart. Data from this trial are expected in the coming months.
- Johnson & Johnson has started a trial of its vaccine for a small number of young people between the ages of 16 and 17. If the vaccine is found to be safe and effective in this age group, the trial will continue with 12 to 15 year olds.
What about COVID-19 vaccine trials for young children?
- Pfizer / BioNTech and Moderna have both started trials in children 6 months to 11 years old.
- These trials will each start by testing doses that are smaller than those given to older children, adolescents and adults. This allows researchers to determine which dose is well tolerated and still gives strong antibody results in young children.
- Once the dose is set, more children in these age groups will be enrolled in placebo-controlled trials to assess the effectiveness of these vaccines.
All of these steps will take some time so that they can be done without cutting corners when it comes to safety. The first vaccines will likely be available for young children in late 2021, or perhaps early 2022.
What is not yet known about COVID-19 vaccines in children and adolescents?
- The duration of vaccine-induced immunity against COVID-19 infection in children will need to be monitored over time. The results of these studies will help experts decide whether children will need COVID-19 vaccine boosters in the future.
- Researchers also need to study whether COVID-19 vaccines can be combined with other vaccines that children receive regularly. For now, the CDC recommends not giving any further vaccines within 14 days of a COVID-19 vaccine. This is true for people of all ages.
- Researchers will need to assess the impact of these vaccines on protecting children against infection with COVID-19 variants. But biologically, there would be no reason to expect differences in variant vaccine coverage in adults compared to children.
Post COVID-19 Vaccines for Children and Adolescents: What We Do – and Don’t Know – first appeared on Harvard Health Blog.
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