“Shared expectations lead to predictability.”
(Editor’s note: with Covid-19 becoming more acceptable by the public, starting this week, the weekly FAQ column will be limited to only 3 topics.)
566. A negative COVID test has never been so meaningless.
Q: If I take a Covid test and it shows “negative,” is it safe for me to visit friends?
A: On June 10, Katherine J. Wu, published an article in The Atlantic that explained that Covid tests are not and never have been perfect, but since around the rise of Omicron, the problem of delayed positivity has gained some prominence. Recently, many people have logged strings of negatives—three, four, even five or more days in a row—early in their COVID course of showing symptoms. No one can yet say how common these early negatives are, or who’s most at risk. But if Covid-19 is rewriting the early-infection playbook, “that makes it really scary,” says Susan Butler-Wu, a clinical microbiologist at USC’s Keck School of Medicine. “You can not test, get a negative, and actually know you’re negative.” Misleading negatives could hasten the spread of the virus. They could delay treatments premised on a positive test result. They also buck the current COVID dogma: Test as soon as you feel sick. The few days at the start of symptoms are supposed to be when the virus is most detectable and transmissible.
Experts aren’t sure why delayed positives are happening. In practice, “it’s really hard to separate if all of this is a property of the virus, or a property of the immune system, or both,” says Roby Bhattacharyya, an infectious-disease physician at Massachusetts General Hospital. More research is now being undertaken.
All of this means that our guidelines and perceptions of the virus may soon need to adjust—likely not for the last time. Butler-Wu, the USC clinical microbiologist, recently advised a friend who had received more than half a dozen negative test results—antigen and PCR—that her respiratory illness probably wasn’t COVID. The friend ended up visiting Butler-Wu, only to test positive shortly thereafter. “That really shook me,” Butler-Wu told me. “It flew in the face of everything I knew from before.”
567. Young children can become vaccinated as early as next week – except in Florida?
Q: Is it true that my 3-year-old son can receive a Covid-19 vaccine by June 24?
A: Finally. On June 15, the New York Times reported that the vaccines from Pfizer and Moderna had been reviewed by the CDC advisory group and approved for younger children. If all goes well, doses for children could be given out as early as next week. The approvals were for Pfizer’s three-shot vaccine for children 6 months through 4 years old, and Moderna’s two-shot vaccine for children 6 months through 5 years old. The advisers voted 21 to 0 to authorize both shots. The F.D.A. has said that clinical trial data from the companies shows that each vaccine meets the criteria for safety and effectiveness in the age group. All states have already ordered supplies of the respective vaccines in the correct dosages for children – except Florida. The Governor of that state stated he was convinced that the federal approvals were not done accurately leaving many questions in his mind about the safety and effectiveness of the vaccines. Local healthcare workers, however, can order supplies directly through the federal program. Many children in Florida may be delayed in receiving vaccinations because of the extra steps that will be required.
568. Children with certain allergies are protected from developing Covid-19.
Q: I read somewhere that kids with food allergies are protected from getting Covid. True?
A: Philip Kiefer, a staff writer at Popular Science, recently published an article that stated, “For reasons that aren’t yet clear, kids with food allergies were much less likely to catch COVID in a new study.” Children with allergies are significantly less likely to catch COVID-19, according to a long-term, National Institutes of Health-funded study published earlier this month. “Historically, those with asthma and allergic disease are susceptible to poor outcomes due to viral infections,” says Max Seibold, a pediatrician at the National Jewish Health Hospital in Denver who led the research. People with allergic disorders share a specific type of inflammation, called Type 2 inflammation. The immune system primarily uses another type of inflammation, Type 1, to fight off viral infections. But for people with allergic disorders, a viral infection can trigger both inflammatory alarm bells. “They have this sort of flamed-out state of their airway with two types of inflammation going on at once,” Seibold says, which can lead to serious illness.
Beginning in the spring of 2020, the team of researchers from multiple US institutes recruited children and teenagers from 12 different US cities. Every two weeks between May 2020 and February 2021, 5,600 participants were tested for COVID, with additional testing of those who became ill. This way, the study authors tracked not only symptomatic or serious COVID cases—which remain rare in children—but asymptomatic ones, too. From that data, they calculated the risk of overall infection and risk of serious illness.
Over the course of the study, allergic diseases affected COVID risk—but not in the way researchers might expect. Children with food allergies were 50 percent less likely to catch COVID, and household transmission was much lower when someone had an allergy. Atopic dermatitis didn’t affect risk. Nor did asthma—unless it was specifically asthma triggered by allergic reactions.
Right now, the team is studying participants’ cells by RNA sequencing. That might show if the participants known to be at low COVID risk actually had the high inflammation predicted in other studies. Cezmi Akdis, editor of the journal Allergy and the director of the Swiss Institute of Allergy and Asthma Research, wrote: “Although the publications are controversial, I think that existing allergy prevents severe COVID development.”
