Where we stand on vaccinating kids, pregnant women and people who’ve already been infected

Some studies under way will wrap up before the school year starts.

(Trent Nelson | The Salt Lake Tribune) Chelsie Stain serves lunch to children at Imagination Time Childcare and Preschool in Marriott-Slaterville on Tuesday, May 12, 2020.

It’s exciting we’re getting people vaccinated at the rates we are — more than 150,000 doses were administered in Utah last week, and that number is only expected to rise. On April 1, all Utah adults are eligible to sign up, but for some the decision is not as easy.

Kids, pregnant women, and those who have had COVID-19 may present different challenges. I want to explain why that is, and what the science says about the vaccination options for these groups.

Vaccines for kids

Teenagers 16 and up can receive the Pfizer vaccine, but not Moderna or Johnson & Johnson. For those younger than 16, we’re still waiting on clinical trials.

As with everything COVID-19 and children, it’s important to not think of kids as one group, but as several different age categories. In many ways, teenagers who have gone through puberty seem to have outcomes similar to — though better than — other young adults, while kids younger than that seem to have additional protective capacities that make symptomatic infection more unlikely.

So for months now, these companies have been testing their coronavirus vaccines in teenagers. Moderna’s “TeenCove” study, initiated in December, seeks to study the impact of the vaccine in about 3,000 12-18 year olds. Pfizer’s vaccine was initially tested in those 16 and up, and the company fully enrolled a study on 12-15 year olds in January.

Biologists have high confidence the vaccine will operate essentially the same in these teenagers as they do with older people, but of course, we need to study it to make sure. The results of these studies are slated to be released “mid-year 2021.″ It appears the researchers are trying to get conclusions in advance of the 2021-22 school year, so June or July is a relatively safe bet.

And now, we’re studying the vaccine in younger kids, too. Moderna announced a Phase 2/3 study Tuesday to test its vaccine in two different age groups: six months to two years old, and two years to 12 years old. Researchers will test the vaccine on 6,750 kids, and experiment with different dose sizes to see which is most effective. On the younger set, they’ll give quarter, half, and full-size doses, and on the older set, they’ll try both half and full doses. Pfizer has not yet started a similar study, but say it plans to this month.

When will we get the results on those trials? “Just looking at the timelines, it’s probably more likely the end of 2021 to early 2022 for younger kids, but maybe it’ll go a little faster than that,” Robert Frenck, director of the Vaccine Research Center at Cincinnati Children’s Hospital and a principal investigator for Pfizer’s research, told Bloomberg.

The Johnson & Johnson vaccine is interesting when it comes to children, not only for it’s one-dose simplicity, but also because it uses an older vaccine technology. That means vaccines of its type have already been used on young children, including for Ebola and RSV. While Johnson & Johnson hasn’t started a study on those under 12 yet, it plans to.

Vaccines for pregnant women

The Centers for Disease Control and Prevention isn’t outright recommending that pregnant mothers get vaccinated, but it isn’t saying they shouldn’t either. These federal officials say it’s a “personal choice.” That’s because the vaccines weren’t originally tested on pregnant women, but all of the signs so far have been positive.

The vaccination trials for Pfizer, Moderna, and Johnson & Johnson generally excluded pregnant women, but a few slipping through — women who didn’t know they were pregnant, or became pregnant after the trial began. A total of 18 pregnant women were “incidentally” vaccinated as part of these trials, and none experienced adverse effects.

More recently, the CDC has been tracking 30,000 pregnant women who chose to be vaccinated, including 1,800 who agreed to provide detailed descriptions of their outcomes. As Harvard Medical School reports, “So far, pregnant people appear to have the same vaccine side effects as nonpregnant individuals. No miscarriages, stillbirths, or preterm births linked with the vaccines have been reported.”

More invasive testing has also done in pregnant animals with the coronavirus vaccines. Again, no red flags were raised.

In particular, it doesn’t appear the vaccine itself — either the mRNA particles in the Pfizer/Moderna vaccines or the modified virus of Johnson & Johnson’s vaccine — end up reaching the placenta. Those are swept away by the body relatively quickly.

What does seem to happen, though, is that after the body develops antibodies in response to the vaccine, those antibodies are shared with the baby. A Massachusetts General Hospital study that tested 10 newborns’ umbilical cord blood after their mothers were vaccinated found antibodies in all 10. A similar study in Israel found the same thing, but with 20 women/newborn pairs.

This isn’t a huge surprise, it’s what happens with most vaccines. But it is basically the best-case scenario: newborns have been actually relatively high-risk with regards to COVID-19, and it appears vaccinating the mother can give those babies antibodies without exposing them to the vaccine injection itself.

Meanwhile, Pfizer does have a trial underway with 4,000 expecting mothers, with the first participants being dosed about a month ago. After that trial finishes in a few months, I expect the CDC will give the full go-ahead.

Vaccines for those previously infected with COVID-19

Right now in Utah, those who have been infected with COVID-19 within the past 90 days are being asked to wait to get vaccinated. The rationale is simple: you already have the antibodies and they’re currently strong, so save the dose for someone else.

That being said, Utah’s decree is a suggestion — if you really want to get vaccinated despite having been infected in the past 90 days, you can. It’s kind of a selfish move, but sure.

Interestingly, studies show those who have already been infected tend to have a stronger immune response to the first dose than those who haven’t already had COVID-19.

And in fact, there are now multiple studies that show that just one dose should be sufficient for full protection for those who have already had the disease. Those studies show 100x to 1000x multiplication in antibody levels after the first dose, but no real change in antibodies after getting the second dose.

That makes sense. For COVID-19 “naive” individuals — people who haven’t been infected — the first dose teaches the body about the virus, and the second teaches the body the virus is an ongoing threat. For those who have already been infected, that first dose acts as that lesson. A second dose is just overkill: “Welp, here’s this virus for the third time this year.”

So those who have already had the coronavirus should definitely get vaccinated eventually, but maybe not multiple times. Still, current CDC and Utah protocol is to give these people both doses, though scientists who worked on the above studies have petitioned the CDC to change that. It takes a lot for the CDC to change its mind, which is reasonable, though reasonable, but some other countries have already dropped it to one shot.

If I had been previously infected, my approach would be “wait and see.” If I had tested positive in the past 90 days, I’d wait for my dose so someone at higher risk could get it. If it had been longer than that, I’d get my first dose ASAP, then use the ensuing 21-28 days to watch the CDC’s page for changes in their protocol.

Andy Larsen is a data columnist. He is also one of The Salt Lake Tribune’s Utah Jazz beat writers. You can reach him at alarsen@sltrib.com.