A Blog by Jonathan Low

 

Apr 24, 2021

How Vaccines Are Turning Covid Into A Young Person's Disease

Older people are getting vaccinated in the US and many other countries at a good rate, though there are pockets of vaccine refusers in rural and conservative areas who object on ideological grounds. 

But the bigger threat to global herd immunity may be young people who, either by dint of vaccine access order or the belief that it doesn't affect them, will now become the primary source of Covid spread. Vaccinations for high schoolers and young adults may now become the most urgent priority. JL

Sarah Zhang reports in The Atlantic, image by Kevin Whitlock, indieonline.com:

Vaccination is already changing the landscape of COVID-19 risk by age. In the U.S., hospital admissions have fallen for adults over 70 who were prioritized for vaccines, but they have remained steady - or have even risen slightly - in younger groups. Over the summer, the number of cases may drop as vaccination dampens transmission while cases among the unvaccinated rise. The unvaccinated group will be disproportionately children. Kids are 8,700 times less likely to die of COVID-19 compared with those older than 85. (But) by dint of vaccine order, COVID-19 will start looking like a disease of the young.

Like many parents, Jason Newland, a pediatrician at Washington University in St. Louis and a dad to three teens ages 19, 17, and 15, now lives in a mixed-vaccination household. His 19-year-old got vaccinated with Johnson & Johnson’s shot two weeks ago and the 17-year-old with Pfizer’s, which is available to teens as young as 16.

The 15-year-old is still waiting for her shot, though—a bit impatiently now. “She’s like, ‘Dude, look at me here,’” Newland told me. “‘Why don’t you just tell them I’m 16?’” But because certain pharmaceutical companies set certain age cutoffs for their clinical trial, she alone in her family can’t get a COVID-19 shot. She’s the only one who remains vulnerable. She’s the only one who has to quarantine from all her friends if she gets exposed. In America, adults are racing headlong into a post-vaccination summer while kids are being left in vaccine limbo. Pfizer’s shot is likely to be authorized for ages 12 to 15 in several weeks’ time, but younger kids may have to wait until the fall or even early 2022 as clinical trials run their course. This “age de-escalation” strategy is typical for clinical trials, but it means this confusing period of vaccinated adults and unvaccinated kids will not be over soon. And the pandemic will start to look quite different.

How different? Vaccination is already changing the landscape of COVID-19 risk by age. In the U.S., hospital admissions have fallen dramatically for adults over 70 who were prioritized for vaccines, but they have remained steady—or have even risen slightly—in younger groups that became eligible more recently. This trend is likely to continue as vaccines reach younger and younger adults. Over the summer, the absolute number of cases may drop as mass vaccination dampens transmission while the relative share of cases among the unvaccinated rises, simply because they are the ones still susceptible. The unvaccinated group will, of course, be disproportionately children. By dint of our vaccine order, COVID-19 will start looking like a disease of the young.

This means vaccines are working, but it also means many Americans are flipping how they think about COVID-19 risk. Adults who spent the past year worrying about their elderly parents are now worrying about their kids instead. The risks are not equivalent, of course: Kids are 8,700 times less likely to die of COVID-19 compared with those older than 85. But “even if the risk is not particularly high, you’re still going to be extra protective of your kids,” says Sandra Albrecht, an epidemiologist at Columbia. “It’s just human nature.”

In coming months, parents may find themselves going back to normal while their kids still have to wear masks indoors. “It’s a very strange relationship to feel protected when your kids are still not,” Jennifer Nuzzo, an epidemiologist at Johns Hopkins, told me. But some 30 million households have children still too young to be vaccinated; in these families, parents and caretakers, especially of the youngest children, will have to keep navigating this incongruous world.


The biggest risk factor to consider for unvaccinated kids, experts told me, is simply how much COVID-19 is spreading in the community. The U.S. is currently vaccinating at a good clip, and even partial herd immunity will slow transmission of the coronavirus. Seasonal effects may drive case numbers even lower in the summer. “If there’s very little virus circulating, that’s a pretty low-risk situation,” says Sean O’Leary, a pediatrician at Children’s Hospital Colorado.

Experts have pegged the threshold where general restrictions can relax at 5,000 to 10,000 cases per day—the point at which risk of COVID-19 is roughly comparable to risk of the flu. (For context, the seven-day average of daily COVID-19 cases in the U.S. reached a low point of 20,000 last summer and peaked at 250,000 during the winter surge; that number has since plateaued at 70,000.) Not everyone will feel comfortable with the same level of risk though. Even before the pandemic, O’Leary points out, parents with children who have high-risk medical conditions were very careful about, say, traveling during flu season. COVID-19 might be another reason for these families to be vigilant.

But already, momentum in the country is shifting toward reopening. States are ending their mask mandates and COVID-19 restrictions. How low cases go in the U.S. later this year will depend on the speed at which we inoculate harder-to-reach populations, as well as continued vigilance among the still-unvaccinated. Letting up after a year of social distancing is tempting, but as my colleague Katherine Wu writes, our vaccine cheat days add up.

Variants may also influence case levels, but it’s not entirely clear how much. Early on, scientists in the U.K. thought the B.1.1.7 strain might be disproportionately more contagious among children than among adults, but the pattern has not held up. That may be because the variant was first detected after schools in the U.K. opened in the fall, explains Oliver Ratmann, a statistician at Imperial College London who has modeled the implications of the variant for kids. Then schools closed and mobility patterns changed over the holidays, which complicated the preliminary trends. The earlier pattern of B.1.1.7 in kids might just have reflected who had a chance to spread the virus at the time, especially because  U.K. schools took fewer precautions, such as mask wearing, compared with many in the U.S. The evidence on whether this variant causes more severe illness is also mixed.

What is clear, though, is that B.1.1.7 is more transmissible than the original virus among all age groups. In some places, that could tip the balance toward rising cases, but other factors are clearly at play too. For example, Michigan has a lot of B.1.1.7 cases and is experiencing a terrible COVID-19 surge, but Florida, which also has high numbers of B.1.1.7, is not. “The variants don’t help, but they’re not fully to blame,” Nuzzo said. The same precautions that worked before—including good ventilation, masking, and social distancing—still work against B.1.1.7.

All of these concerns could come to a head in schools, which are one of the main places where unvaccinated people—e.g., kids—will congregate. As the U.S. is already seeing, school outbreaks do happen, but they can be contained with precautions in place. This means younger kids, who likely won’t get vaccinated before the fall, may have to continue to wear masks indoors. But the benefits of in-person schooling are significant enough, experts told me, that schools should open even if kids can’t get shots yet.

The trickier question is what kids can do outside of school when it comes to playdates, sports, and extracurricular activities. In Michigan, officials have suggested that high-school athletics and the socializing around sports—rather than classes themselves—are driving the uptick in cases among teens. Parents and kids will have to decide together which risks are worth taking. Newland told me his 15-year-old daughter sees her core group of friends and plays sports. But she’s decided to keep taking virtual classes, even though her risk of contracting COVID-19 at school is low, because exposure to any cases at school could trigger a quarantine that keeps her from playing sports, which is important to her. That’s the tradeoff they’ve decided to make, but they’d of course prefer not having to make it. As Newland said, “I feel much better about my other daughter, who got vaccinated at 17.”


At least 15-year-olds have an end in sight; they are likely to be eligible for Pfizer’s vaccine soon. Parents of younger kids may have to keep making these split decisions a lot longer. In their strange world, a dinner party with their adult friends is fine, but a birthday party for their 5-year-old could still spread the virus. When I asked several experts about a hypothetical party for unvaccinated preschoolers in the fall, they told me they would continue to think about ways to reduce risk, such as keeping the gathering small and outdoors. These assessments are hard to make in advance: We don’t know exactly what the situation will look like and how much the virus will still be circulating. Perhaps COVID-19 will have faded enough that people won’t be spending every waking minute thinking about the virus anymore. Perhaps not.

To make these decisions more difficult, the situation probably won’t be the same everywhere in America. Already, rural residents report less interest in getting the shots than people living in cities and suburbs. Whether because of vaccine hesitancy or unequal access, “I think there’s going to be a huge amount of variation geographically,” says Whitney Robinson, an epidemiologist at UNC Gillings School of Global Public Health. The virus may continue to circulate in pockets of the country where not enough eligible adults are vaccinated. These adults plus still-ineligible kids could add up to a pretty large pool of susceptible people.

Ultimately, the risk to unvaccinated kids later this year depends on the actions we take now. The faster we vaccinate and the better we suppress cases through other measures, the safer the situation will be for anyone who remains uninoculated in the fall. Then, finally, parents can stop telling kids to do things that they themselves are not doing—which, as former kids I think can agree, is literally the worst.



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