Pandemic-related immunity gap in kids explains surge of respiratory infections in children in China, says WHO

Reports this week that China is experiencing a surge in respiratory infections in young children triggered flashbacks of the start of the Covid-19 pandemic among infectious disease watchers. But a rapidly organized meeting Thursday between the World Health Organization and health officials in China assuaged much of that concern.

The evidence presented to the WHO team pointed to what’s sometimes called an immunity gap that was created by the pandemic. A dramatic reduction in circulation of other viruses and bacteria created a cohort of kids with few immunological defenses against bugs like influenza, RSV, and other cold-causing viruses, setting the stage for large outbreaks when those pathogens returned.

Maria Van Kerkhove, acting director of the WHO’s department of epidemic and pandemic preparedness and prevention, spoke to STAT on Friday about what the agency learned in the meeting, why this event set off such concern globally, and where things stand with Covid.

The conversation has been lightly edited for length and clarity.

WHO asked China for surveillance data but also for laboratory results. What kind of evidence did you get that what they’re seeing is what they told you they were seeing?

What they were giving us was an overview of current trends in acute respiratory illnesses across the country. And they were giving us some readouts from that surveillance system based on age. So, looking at the youngest age groups, looking at school-aged kids. They also gave us a readout on a new multiple pathogen surveillance system that started in mid-October looking at 13 pathogens — 10 viruses, three bacteria.

And we also utilize our Global Influenza Surveillance and Response System. Of course, we were checking the genetic sequences that were submitted to GISAID [a global sequence database] and looking at the variant circulation. There’s different ways that we cross-referenced some of that information.

And then we specifically asked about clustering: Are you seeing a clustering of undiagnosed pneumonias? And they said no. They gave us the percentages of what is due to influenza, rhinovirus, adenovirus, mycoplasma pneumoniae.

And you think the immunity gap explanation is plausible?

Yes, that immunity gap opening up and new detection methods to be able to capture the incidence of these types of pathogens around the country. This is not an indication of a novel pathogen. This is expected. This is what most countries dealt with a year or two ago.

We asked about comparisons prior to the pandemic. And the waves that they’re seeing now, the peak is not as high as what they saw in 2018-2019.

When you say the peak isn’t as high as before the pandemic, are you talking about specifically in this age group?

Yeah, in this age group.

We asked some key questions like, are there any patients that were not diagnosable? No, they were infected by known pathogens.

We asked if anything new was detected, any new variants, any new subtypes? And the answer was no. We asked if [they] have seen any unusual disease presentations for these pathogens. And they said no. And then they gave us an overview of the burden in the health care facilities, and their hospitals are not overwhelmed. There’s a lot of fever clinic visits, a lot of outpatient visits, but in terms of hospital beds, ICU, they’re not at capacity.

Why do you think this sort of blew up in the last few days?

It’s that combination. You hear “undiagnosed.” People think, well, that means they must have ruled everything else out, and therefore it’s probably new. You hear “clusters,” which means there’s some people linked in space and time. “Children” — which is always alarming — “with pneumonia,” which indicates a level of severity. And you hear “China.” So I think a lot of people were immediately drawn back to the beginning of the Covid pandemic and thought: Oh God. Not again.

For us, it was really important to be so quick in releasing the information so that we could show that yes, these are systems that are in place tracking these diseases and this is an overall increased wave, not discrete clusters. Basically, that signal that we were trying to verify was, in fact, not really a signal. It was just an indication of an overall transmission increase across the country.

I get why this triggered people. But the fact that the cases were only in children pointed away from a new pathogen, didn’t it? Because if it was something new, everybody would have been susceptible.

Right. This is not the same situation that we were in in December 2019 and January 2020.

Covid has really dropped down the news priority list, and people are so tired of it. But how do you feel about where we are with Covid right now?

We’re in a much better place. I think the population level immunity is holding up fairly well because of whatever vaccination took place, plus infection over time. The concern I have is in the complete unwillingness to talk about Covid and its risk at an individual level, and really among the most at-risk people.

We don’t have nearly enough attention on post-Covid condition. And the thing that drives me and keeps me up is because there’s so much fatigue to talk about Covid, we’ve become complacent. That oh, it’s just another one of these diseases that kills people, but we’re OK. And that’s not OK.

The biggest worry I have right now is the dismantling of systems. Completely. Completely. So everyone’s talking about the next future pandemic threat while we’re actually dealing with a virus that is simmering, that’s evolving, that’s changing. We have no surveillance on the virus in animals. We have a lot of people getting reinfected, which we don’t understand the long-term implications of, beyond post-Covid condition. The world has become complacent because it’s been so traumatic.

A lot of people are focused on climate change now, as if there’s no link between pandemic preparedness and climate change or infectious diseases. It’s a continuum.

I recently heard a panel about the pandemic during which one of the speakers said the world is experiencing collective global amnesia with rapid onset. It reminded me of reading Alfred W. Crosby’s book on the 1918 pandemic, “America’s Forgotten Pandemic.” I couldn’t understand how an event like that could have been forgotten. But we’re watching this happen with Covid in real time.

This is a collective trauma that we want to forget. Governments can’t.

The WHO’s ask of governments is not to do what you did for Covid two years ago. It’s to make sure the capacities that were increased are sustained for all of these other infectious threats that are there, that will change because of climate change, that will change because of war and displacement, that will change because of things like El Niño.

There is a constant threat that governments need to focus upon. But individuals don’t need to be living their lives in fear.