COVID shot

New strains of the COVID virus are now widespread in Arizona, which could account for a worrisome increase in cases among children, according to health officials.

Hundreds of cases caused by one of the more infectious variants have been detected in Gila and Navajo counties.

“They’re not testing every sample, so we have a lot more than we realize — and a lot more infections among children,” said Navajo County Public Health Director Janell Linn this week.

Prior to January, 5% of the new infections were among children. But as overall cases declined, the share of new cases in children increased. In January, children accounted for 13% of cases, rising to 17% in February, 26% in April and 23% in March.

Fortunately, school is now out and the federal government has approved use of the safe and highly effective Pfizer vaccine in teens aged 12 to 18. Approval of the Moderna vaccine in kids is expected shortly. Epidemiologists say tests could be complete to allow the use of both those vaccines in children 6-12 in the fall.

The worrisome rise in infections among children comes as the mass vaccination campaign slows — especially in states like Arizona. The big drop in daily cases thanks to the number of vaccinated so far and the state’s decision to drop most restrictions has convinced many people to not get the shot, although we remain far from the protection of herd immunity.

The faltering of the vaccination efforts and the rise of the variants come as scientists have begun to unravel the mystery about why some strains spread much more quickly — and why children until now have been less likely to get infected or become seriously ill.

The new research provides a dark lining to the otherwise encouraging decline in infections — both nationally and in Apache and Navajo counties.

Nationally, 62% of adults have had at least one shot and the number of new cases has dropped by 45% in the past two weeks as a running daily average.

Arizona’s lagging behind when it comes to vaccinations — with just 37% of the population fully vaccinated and 47% have had at least one dose. As a consequence, the daily number of new cases in Arizona has dropped by an average of just 27% in the past two weeks. Arizona’s still reporting about 400 new cases daily — a rate of about 7 per 100,000.

In Gila County, some 42% are fully vaccinated and new cases have declined by 46% to 4 per 100,000.

So if it weren’t for the spread of the more infectious and potentially more deadly variants — Arizona could feel more confident.

But the variants that have devastated India, South America and Africa have apparently evolved new ways to evade the immune system — potentially endangering children in the process.

The “Alpha” variant that caused a third wave of new cases and school lockdowns in England has likely become the dominant variant in Arizona, according to limited genetic testing of new cases statewide.

Alpha has 23 mutations. Initially, researchers focused on the eight mutations in the spike protein that enables the virus to smuggle itself into cells in the body — which it then turns into deadly viral factories.

However, additional research has focused on other mutations that enable Alpha to thwart the early warning system of the immune system, according to a report posted online by researchers from the Yale School of Medicine — but not yet published in a peer-reviewed scientific journal.

The variant has a gene that produces proteins that apparently delay the production of interferon — the immune system’s most important alarm. Alpha floods the area with a protein that blocks the interferon alarm, which makes it all but invisible to the immune system for about 12 hours.

Once the immune system gets the alarm sounding again, the virus has built up its numbers. This kicks the immune system into overdrive — with coughing, fevers and other responses that actually hasten the spread of the virus to others.

The researchers found a similar mechanism in the Beta variant first identified in South Africa and the Delta variant first identified in India. Those variants also initially depress the production of interferon. However, they use a different mechanism than Alpha, the researchers concluded.

Perhaps that’s why infection rates among children are rising.

Researchers have long puzzled over why the immune systems of children seem to make them less likely to get infected and develop serious disease when exposed to the COVID virus. Some evidence suggests children rely more heavily on interferon for their immune response than adults. So while the new variants like Alpha are 50% to 70% more infectious for everyone — they might also at least partially neutralize the resistance to infection among children.

“We have it on the radar that we could experience spikes in the fall” if people don’t get vaccinated, Linn said.

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