Thread by @hjillianh

SARS-CoV-2 Infections Among Children in the Biospecimens from Respiratory Virus-Exposed Kids (BRAVE Kids) Study | medRxiv medrxiv.org/content/10.110…

A prospective cohort study evaluating #SARSCoV2 exposure in a community sample of 382 kids, including epidemiological and clinical characteristics, detailed symptom descriptions, and viral load analysis of nasopharyngeal swabs

About the cohort:
1. Kids ages 0-<21
2. All had a documented close contact with someone who had confirmed SARS-CoV-2 from 2 days before symptoms started to 7 days after (or positive test for asymptomatic contacts)-most were in the same household
3. 81% Hispanic

Comorbidities included obesity and asthma.

For families who consented, we conducted home visits and collected blood, a nasopharyngeal swab, and a fecal sample (we only talk about the NP swabs here). If we couldn’t conduct a home visit, we dropped off a self collection kit: mid-turbinate nasal swab and fecal sample

At enrollment, All families completed a phone interview to gather info on medical history, exposures, sociodemographics, and any symptoms

We also conducted a follow-up phone interview 7 days after enrollment to assess symptoms. If any of the enrolled kids in a household had symptoms, we followed up at 14 and 28 days after enrollment

We chart reviewed everyone too, and recorded results of any clinical respiratory virus testing

Risk factors for infection after close exposures:
Hispanic ethnicity and having a close infected contact who was your sibling. A significant portion of the kids with infected siblings didn’t have infected adult contacts - maybe suggests sib-to-sub transmission?

Protective factor: having asthma! 9% of the kids in the cohort had provider-diagnosed asthma (about what you would expect for the local population), so we’re working with small numbers, but this strikes me as weird

Symptoms: 30% of the kids were asymptomatic, and the most common symptoms were what we’ve seen in adults-fever, cough, etc

Compared to kids 0-5 and 14-21, kids ages 6-13 had the fewest symptoms, shortest symptom duration, and were more likely to be asymptomatic (39%!)

Now for the viral load data with caveats: viral copy number doesn’t equal amount of infectious virus (although maybe they correlate?). You can also have sampling issues when you swab - some investigators really get a nice swipe, but sometimes your participant is uncooperative

We did not find any differences in viral load between different age groups, types of symptoms, or in symptomatic vs asymptomatic kids

We did see a strong downward trend in virus levels based on when the sample was collected with respect to symptom onset: the highest viral copy numbers were found in the 3 days before and 3 days after symptom onset. Then it drops pretty quickly.

So what does this all mean?

1. We can’t really make conclusions about how kids transmit the virus, since we couldn’t determine the order of transmission. We found kids to enroll by looking at all the testing data each day and calling up households that had someone whose was positive.

Symptom onset timing and asymptomatic cases make it difficult to tell who brought the virus into a household

Because we identified kids based on positive tests, our sample@of kids reflects changes in testing strategy over time - I need @IbukunMD to comment there, as she is the @Duke_Childrens guru in this area

While some kids had clinical testing and a research dawn performed, some kids only had a single sample-this could lead to some missed positives

We show that kids under 5 don’t develop lost of taste or smell, and have lower levels of flu-like symptoms, but that could be because little kids can’t really report those

See cautions above about viral load data

What I think this means: we should think really carefully about screening strategies in schools and congregate childcare settings. It’s harder to spot kids ages 6-13 who may be infected

I also really want to figure out what’s going on in kids with asthma and to take a closer look at kids who are Hispanic. I think a lot of the differences we’re seeing may lie in systemic racism and the disproportionate impacts of this pandemic on people of color

We also really need a definitive study on child viral transmission. We’ve got ideas, but need time and money. Good #epidemiology studies are really hard

There were a bunch of amazing people who worked on and supported this study: @SalliePermar @AlexRotta @Duke_Childrens @DukeCHDI @AnnReedMD @TheDHVI @DukeMedSchool @snaggie1 and many others

Also my husband @chrisecramer who has been listening to me moan about this study since March and who picked up the slack at home when I was off picking up poop samples

Many, many thanks to Matt Kelly (who isn’t on Twitter) for being an amazing PI for this study.

One last thing- the @DukeMedSchool students are amazing. We could not have done this study without them! I’m selfishly hoping they all decide to go into pediatrics. Keep an eye out for them when they all go up for the match in the next year or two!