Is RSV Being Misdiagnosed as COVID-19?

In many parts of the United States, COVID-19 is affecting children more now than at any time this pandemic. 94,000 children were diagnosed with COVID-19 last week alone. The Delta variant appears to be causing more severe illness per the experience of multiple pediatricians, e.g.:

As Dr. Seth D. Kaplan, president of the Texas Pediatric Society, said,

We’re seeing a significantly greater number of children who are being hospitalized with COVID-19. Some are requiring ICU care, more than we’ve seen with previous surges, and that’s related to the increased transmissibility of delta. This is just a more aggressive variant. It’s sickening more children, and requiring more to be hospitalized.

While the rate of negative outcomes for children is still very low fortunately, the overall harms can add up to non-trivial numbers when this many children get infected. At least I feel that way. According to the CDC, an average of 239 children are being admitted to the hospital every day, the highest level of the pandemic so far.

Over 200 children were diagnosed with MISC-C in July, and children with MIS-C are really sick, most needing treatment in the ICU. According to the American Academy of Pediatrics, 22 children died of COVID-19 from 7/22/21 to 8/05/21.

Faced with these numbers, a suggestion emerged that perhaps COVID-19 really isn’t that bad, as children are being overdiagnosed with the virus. I first encountered this idea from Dr. Tracy Beth Høeg, a sports medicine doctor with a PhD in Epidemiology and Public Health. Dr. Høeg wondered on Twitter if the increases in COVID-19 diagnoses were perhaps due to misdiagnosis of RSV:

The observation that prompted Dr. Høeg’s query was, “the 0-4 year olds driving up COVID hospitalization rates recently. 5-17 year olds have decreased/remained stable.” As she explained, a hospitalization due to RSV could be mis-labelled COVID-19 if they have a positive COVID test:

This notion garnered attention from a cadre of contrarian doctors who have largely denied that COVID-19 can cause severe illness in young people. Dr. Høeg also said, “Please teach me. Tell me if I am wrong. I don’t have all the answers”. I don’t have all the answers either, but I will try to clarify the issue.

Respiratory syncytial virus (RSV) is a very common respiratory illness that can present with a runny nose, fever, wheezing, and a cough. It can spread to the lower respiratory tract, causing pneumonia or bronchiolitis. It can be quite severe, even deadly, in infants younger than 6 months or children under 2 years with chronic heart and lung conditions. According to the CDC, which tracks the virus, each year in the US RSV causes “approximately 58,000 hospitalizations with 100-500 deaths among children younger than 5 years old”.

Though it is usually a winter virus, it was basically absent the past winter due to pandemic restrictions. It is increasing now as people emerge from pandemic isolation, and many hospitals are seeing large volumes of children with RSV. Both RSV and COVID-19 are serious diseases, and a few children have both viruses.

So, are large numbers of children with RSV being misdiagnosed as having COVID-19? Do you really need to ask? As pediatrician Dr. Jennifer Chen noted, the two are unlikely to be confused unless you are trying to confuse:

Let’s explore why this is so.

The source for Dr. Høeg’s data about COVID-19 hospitalization rates is a federal database called COVID-NET. According to the CDC, “COVID-NET is limited to COVID-19-associated hospitalizations captured in the COVID-NET surveillance area.” In other words, a child has to have a positive test for SARS-CoV-2 to be included in the database, though some children who have been hospitalized for other reasons and happen to test positive have been counted.

COVID-NET covers only about 10% of the country. As such, the absolute numbers of pediatric hospitalizations reported by COVID-NET are quite small. The doubling of the hospitalization rate for children ages 0-4 years from week 28 to 29 was an increase of only 11 cases, and the 22% drop from week 29 to 30 was a decrease of only 5 cases (ages 0-4 are in yellow, ages 5-17 are in blue in the graph below). There were many other weeks earlier in the pandemic where younger children had a higher hospitalization rate than older children, even though RSV was not circulating at that time.

Moreover, the last data point from when Dr. Dr. Høeg made her comment shows hospitalizations decreasing for children ages 0-4 and increasing for children ages 5-17. As older children are not hospitalized for RSV, this is the exact opposite of what one would expect if RSV was being inappropriately diagnosed as COVID-19. Of course, the hospitalization rate for children older than 12-years will be somewhat blunted by the fact that millions of them are vaccinated, though the overall vaccination rate remains depressing low.

As the graph of COVID-19 hospitalization rates shows, there are some broad trends throughout the year, but the numbers jump around erratically from week to week. Trying to find a meaningful pattern based on a few weeks data of a small number of cases is a bit like finding faces in clouds – it reveals something interesting about the person who discovers the “pattern” and nothing at all about the virus.

Pediatricians on social media were justifiably furious at the suggestion that they could not distinguish between these two viruses:

Pediatricians were very confident they could tell the viruses apart on clinical ground alone, in addition to the separate tests that exist for these diseases. RSV is diagnosed with a rapid antigen or PCR test, which is more likely to be used in the hospital setting. COVID-19 is, of course, diagnosed with a PCR test, and false positive tests are extremely rare.

For a child to be mistakenly diagnosed with COVID-19 when they actually have RSV, it would have to mean that their pediatrician is unable to distinguish these diseases clinically, the COVID-19 test would have to be a false positive, and the RSV test would have be to a false negative. Basically, as noted by Dr. Rebekah Diamond, the only way large numbers of children with RSV could be misdiagnosed with COVID-19 is if pediatricians and labs throughout the country were abysmally incompetent:

Notably, the doctors who now question whether COVID-19 is being misdiagnosed as RSV only consider that COVID-19 is being overdiagnosed, not the reverse. Early this summer when COVID-19 rates were falling and RSV rates were increasing, these doctors didn’t wonder whether COVID-19 was being misdiagnosed as RSV. This is quite revealing.

We should be honest about why someone would suggest that RSV is being misdiagnosed as COVID-19. It is clearly just another attempt to minimize COVID-19 by casting doubt on the fundamental numbers that we rely on to make judgments about the pandemic. It is also an attack on the basic competency of frontline pediatricians and laboratory pathologists caring for the sickest children with COVID-19. What they are really saying boils down to: Don’t believe the numbers you read or what the frontline pediatricians are saying. COVID-19 isn’t really so bad for kids after all.

But if you chose to believe the numbers provided by the American Academy of Pediatrics and the reports of frontline pediatricians, as I do, COVID-19 is actually pretty bad for a lot of children right now. This reality can’t be wished away. As Alex Haley said, “Either you deal with what is the reality, or you can be sure that the reality is going to deal with you”.

Of course, when there is evidence the numbers are problematic, it is important and necessary to point this out. As I have written previously, incidental COVID-19 diagnoses have led to the overcounting of pediatric hospitalizations and even potentially the overcounting of pediatric deaths. However, there are also reasons these metrics can be undercounted. Those who seek to convey complete and accurate information will acknowledge both sources of error. In contrast, those who wish to advance a narrative that COVID-19 isn’t that bad for children will instead only acknowledge the overcounting of COVID-19.

Doctors who claimed that COVID-19 was essentially harmless to children or that the vaccine was too risky, are now being confronted with overwhelming evidence that the virus is quite dangerous to a substantial number of them. While COVID-19 was always a danger to some children, it seems to be especially the case with the Delta variant. Children old enough to be vaccinated have died from the virus.

Sadly, few COVID-contrarian doctors are willing to adjust their prior beliefs, even as pediatric hospitals are full of really sick children and some children are dying. Having built their brand with editorials, news interviews, and Twitter hot takes, these doctors are now unwilling to even acknowledge the veracity of the grim statistics that opened this article. Uncomfortable facts become unmentionable facts.

Doctors who wish to avoid reality by suggesting that COVID-19 is being misdiagnosed are obligated to prevent compelling evidence this is the case. They do a grave disservice to children when they make absurd insinuations based on random data fluctuations of a very small number of patients. Much more is at stake here than attention-generating social media hot takes from COVID-contrarians.

Sadly, the myth that children with COVID-19 actually have RSV may already be influencing both public opinion and policy decisions. In Florida, where 32 children were hospitalized every day with COVID-19 the last week of July, Governor Ron Desantis clearly articulated what the contrarians clearly implied. He said,

COVID, I view as a very minor risk… When you see pediatric admissions, some of the may be COVID positive, or suspected COVID, it may ultimately turn out that RSV is what they end up being treated for.

There are real-world consequences when doctors with large, public platforms spread misinformation about COVID-19. This is true even if they claim to be very humbly “just asking questions“.