With the broadest vaccination campaign in history underway to prevent further spread of COVID-19, guidance for who should be vaccinated has focused first on adults, starting with healthcare and other essential workers, the elderly and those with medical conditions.
The focus on adults raises some questions: Why are children last in line to receive the vaccine? And what is the role of children in achieving herd immunity?
There are good reasons to pursue the immunization of children. Chief among them is the suffering the disease has caused: as of mid-February, more than 3 million U.S. children had tested positive and nearly 250 died of COVID-19, posing a greater threat to children than influenza in a typical year.
Furthermore, children may hold the key to herd immunity, the point at which most of a population is immune to an infectious disease, thereby protecting those who are not immune. Experts estimate that at least 70% of the U.S. population would need to be vaccinated or recover from COVID-19 to achieve herd immunity.
If we don't vaccinate children 18 and under, who account for 22% of the U.S. population, about 90% of adults would need to receive COVID-19 shots. Such a scenario is improbable because vaccine supply is still limited and because 4 in 10 Americans say they are unlikely to be vaccinated.
Should the vaccines prove both safe and effective in children, and enough parents consent to have their children vaccinated, another good reason to vaccinate them is that a high level of immunity in one age group that plays a role in transmission can create herd immunity in other age groups. For example, vaccines against the flu and respiratory diseases such as pneumonia are less effective in older adults than in children, so immunizing children can help prevent the spread of those diseases and protect older adults.
In fact, children and adolescents must be vaccinated to get the pandemic under control. Once a high percentage of the population is vaccinated or has had COVID-19, the disease may be no more disruptive than annual influenza seasons. Similarly, multisystem inflammatory syndrome in children (MIS-C), an excessive immune response in those infected with COVID-19, would likely become an even more rare diagnosis.
History shows that vaccinating children prevented the spread of many infectious diseases where they played a significant role in transmission. For example, routine vaccination of teens and children proved effective in eradicating smallpox worldwide and in controlling diseases such as polio, mumps, and measles.
Except for a very few serious allergic reactions, approved COVID-19 vaccines given to hundreds of thousands of adults appear safe. Nonetheless, the vaccines may work differently in children, because their immune systems differ from adults; children may need smaller doses, for example. Even after vaccines have been approved for children, their safety will need to be monitored closely.
Researchers typically study vaccine safety first in adults, then gradually lower the age of research participants.
Pfizer's COVID vaccine has been authorized for ages 16 years and up, and Moderna's targets those 18 and older. Both have begun clinical trials for children 12 and older. Although the timing is difficult to predict, 12-year-olds could be eligible for immunization by late spring or summer. Vaccination trials for children 6 months to 11 years old could start by spring or summer and, if all goes well, the vaccine could be available for those ages in late 2021.
Johnson & Johnson's vaccine was recently approved for people 18 and older, and the company just announced plans to test its coronavirus vaccine in infants and even in newborns, as well as in pregnant women.
Over time, children are more likely to be vaccinated than adults for three reasons: in general, their risk of contracting diseases is higher than it is in adulthood; children see physicians more regularly; and all 50 states require vaccinations for most public-school students. Once deemed safe, prioritizing COVID-19 vaccinations for children would allow us to protect them more quickly, not to mention others they might infect.
This fact alone suggests that including a coronavirus vaccine among routine childhood inoculations should be part of an effective strategy to achieve herd immunity for COVID-19 in the U.S. and around the globe.