Should parents be worried about vaccine effectiveness for 5- to 11-year-olds? An expert weighs in

Vaccinated children ages 5 to 11 were about 46% less likely to need medical treatment for Covid-19 from an urgent care clinic or emergency department, compared with unvaccinated children, a previous CDC study found. That study also revealed vaccination appears to protect against severe disease: Out of almost 1,700 total admissions, there were 59 unvaccinated children in this age group admitted to the hospital with Covid-19, compared with just two who were vaccinated.

Why is this happening? How worried should parents and caregivers be? Do the new data mean they should keep masks on their kids in school and avoid indoor extracurriculars? What are implications for kids with underlying medical conditions? And what's the update for kids under 5?

To guide us through these questions, I spoke with CNN Medical Analyst Dr. Leana Wen, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She is also author of "Lifelines: A Doctor's Journey in the Fight for Public Health" and the mother of two young children.

CNN: Why do you think the Covid-19 vaccine may be less effective in younger children than older children?

Dr. Leana Wen: First, I want to urge everyone to keep these data in perspective. The vaccines in younger children still appear to protect against severe illness, and that's the most important reason we get vaccinated: to prevent hospitalization and death.

Scientists don't know as to why the vaccine shows less effectiveness in younger kids compared with older kids and adults. The most likely explanation is that it's related to dose. The dose of the Pfizer vaccine given to 12-year-olds and above is 30 micrograms, compared with 10 micrograms for those ages 5 to 11. The higher the dose, the higher the possible side effects -- that's why a lower dose was chosen for the younger group. It's possible that this lower dose resulted in less effectiveness.

There are some other explanations of the data. It's possible that by the time of the Omicron infection, so many young children had been exposed to Covid-19 that the effect of vaccination was reduced. It's also worth noting that effectiveness against symptomatic infection also wanes in adults, and that's why the CDC recommends the booster dose for all those 12 and older. Still, we can see that vaccination is still protective in this younger age group against severe illness.

CNN: How worried should parents and caregivers be? Should they rethink their decisions to remove masks and allow their kids to participate in extracurricular activities and indoor playdates?

Wen: The decreased protection is against symptomatic illness. It's certainly disappointing, but I don't think this alone should make them second-guess their decisions about removing masks and resuming extracurricular activities.

The main reason is that the level of Covid-19 is much lower in most parts of the United States compared with even a few weeks ago. In the state of Maryland, where I live, the seven-day average of daily cases was around 15,000 per 100,000 people during the peak of Omicron in January. It's now just over 2,000 per 100,000, according to the CDC. That means the risk of contracting Covid-19 is reduced more than sevenfold now compared with two months ago.

Vaccines continue to provide some protection against symptomatic disease, but most importantly, it shields against severe illness. As a result, I don't think parents should have to rethink their decisions. If members of their household are vaccinated and boosted if eligible, and if they live in areas that are classified as either "low" or "medium" Covid-19 community level by CDC's new tracker, I think it's reasonable for families to allow their children to resume all pre-pandemic activities. That includes going to school without a mask and participating in extracurriculars and indoor playdates.

CNN: What are implications for kids with underlying medical conditions, or children who live with adults who have them?

Wen: It's important to discuss the specific risks with your medical provider. Some people have certain medical conditions that clearly predispose them to severe illness if they contract Covid-19. Being moderately or severely immunocompromised, for example — if the child or someone in the family has cancer and is on chemotherapy, is an organ transplant recipient on immunosuppressants, or other similar conditions. There are also other conditions that make it more likely for the individual to end up in the hospital: those with advanced age or who also have multiple chronic medical problems like diabetes, obesity and lung disease, for instance.

There are other medical conditions that need to be treated but that don't necessarily result in severe illness due to Covid-19. A child who has asthma would be in this category, for example. Speak with your medical provider to understand what your child's and other family members' risk of severe illness is due to Covid-19. If someone in the household faces a substantial risk for severe illness despite vaccination, you should all take additional precautions — such as continuing to wear a high-quality mask (N95, KN95, or KF94) when in indoor crowded settings.

CNN: What's the latest for when vaccines will be available to children younger than 5?

Wen: For children under 5, Pfizer is testing a smaller dose (3 micrograms, compared with 10 micrograms for those 5 to 11), as a three-dose vaccine. Those results are expected in April.

Moderna's data are also expected in the next month or so. Its vaccine dose is higher (25 micrograms) for children 2 to 5 years old, and it's being tested as a two-dose series.

Families with young children need to make the best decisions for themselves about the level of risk they are willing to take while awaiting the vaccine. Some may still wish to take additional precautions, especially if they live in areas with high Covid-19 community levels. Others may decide that the level of Covid-19 in their area is low enough, and the value of resuming pre-pandemic activities high enough, that they will resume indoor playdates and other activities they have been missing.

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