Why herd immunity could also be unattainable with out vaccinating youngsters in opposition to COVID-19

Why herd immunity may be impossible without vaccinating children against COVID-19

Rodney E. Rohde, Texas State University

A significant figure: 20% of the US population is under 16 years of ageUS Census Bureau, CC BY-ND

It may be summer before children under 16 can be vaccinated against COVID-19 in the United States. This is a problem in achieving herd immunity quickly.

Children make up a significant portion of the population – approximately 65 million are under the age of 16, which makes up 20% of the people in the United States. While children seem less at risk of serious illness or death, they can still spread the virus. Many young children who contribute to the transmission are still unclear.

Some simple calculations show why America has a problem with vaccination numbers.

America's problem with vaccination numbers

Initially, it looked like herd immunity could be achieved when 60-70% of the population was immune. Herd immunity means that enough of the population has either been vaccinated or obtained immunity through natural infection to stop the virus from spreading.

However, research and expert opinion show that this number is likely much higher – in the 70 to 90% range due to the emerging highly transmissible virus variants.

Children under the age of 16 who cannot receive the vaccine can immunize 80% of the US population. A tiny percentage of these adults should not be vaccinated because of severe allergies to any ingredient in the vaccines or other serious health problems.

But not all remaining adults plan on getting the vaccine. A large percentage – 32% in a recent national survey – say they are either likely or definitely not to be vaccinated. In another survey, almost half said they only get the vaccine when they need to, or that they want to wait and see and see how it works for others.

Without comprehensive vaccination of children to reduce COVID-19 transmission, herd immunity simply won't happen.

What about natural immunity?

You may be wondering: what about all the people who have already been infected?

To date, around 28 million COVID-19 cases have been confirmed in the US. Because large numbers of infected people never show symptoms, the CDC estimates that 83 million people in the United States were actually infected last year – about a quarter of the population.

However, for now, researchers don't know how long natural immunity will last. The Centers for Disease Control and Prevention recommend that people with COVID-19 should continue to be vaccinated.

The vaccination efforts will continue to affect the pandemic even if herd immunity lasts longer. As former CDC director Tom Frieden told me, "Even without children being vaccinated, vaccinating adults will greatly reduce deaths and could reduce the spread."

When can children be vaccinated?

One of the main questions parents have to ask is when children can get the vaccine. The short answer: we don't know yet.

First, the national vaccination process is still going on, starting with the medical staff and the most vulnerable adults. Approximately 1.5 million people receive the vaccine every day, and each needs two doses.

Second, the two federally approved vaccines are only approved for adults and older teens – Moderna 18+ and Pfizer 16+.

Drug manufacturers have to conduct extensive tests on thousands of subjects to show that their vaccines are safe and effective. While the FDA has expedited COVID-19 vaccine trials for adults, the process will likely take longer for children due to factors like safety data. Depending on the vaccine technology, this data can take up to six months for children compared to two months for adults.

Description of the differences between mRNA and traditional vaccinesVaccines help the immune system recognize viruses, typically by injecting a weakened virus or virus proteins. Instead, Pfizer and Moderna vaccines use mRNA, the molecular instructions for building virus proteins. @ VI4research, CC BY-NC-SA

Moderna also struggled initially to find enough volunteers for its youth trials. By mid-January, the company had only enrolled about a third of the 3,000 volunteers it needed. Pfizer's clinical trial for adolescents has completed recruitment but has not released any publicly published data.

For younger children, Moderna's CEO reported in January that the company would likely soon begin clinical trials between the ages of 1 and 11. Pfizer has not released details for this age group.

A third vaccine could also be in the mix soon. FDA advisors are expected to discuss Johnson & Johnson's application on February 26th.

Frieden said it was likely that youth vaccines could be approved by the summer. This would add children aged 12 to 15 to the list of eligible vaccinations – another 5% of the US population.

Dr. Anthony Fauci, the President's chief medical officer for COVID-19, recently suggested a similar timeframe. Vaccination trials in younger children will begin in the "next few months," Fauci said, and "when we get to late spring and summer we will have children who can be vaccinated."

This article has been updated with new numbers in the vaccine distribution table.

Rodney E. Rohde, Professor of Clinical Laboratory Science, Texas State University

This article is republished by The Conversation under a Creative Commons license. Read the original article.


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