It’s time to stock up on tissues, bingeable TV options and Covid-19 tests. Yes, many signs are pointing to a Covid-19 summer surge – although one that’s far less intense than what emerged the past few summers.
Experts say they do not expect that cases will be severe or that the uptick will be prolonged, and there are early signs from wastewater data that this wavelet may already be leveling out.
But data posted this week by the US Centers for Disease Control and Prevention shows that many Covid-19 indicators, including hospital admissions, emergency department visits and test positivity, are once again on the rise.
Independent commercial laboratories are also noting the increase.
“When we look at our data, we have noticed that since late June to the beginning of July and probably through now, there has been a mild uptick in cases and these are based on samples sourced from pharmacy-based testing and also from health system-based testing,” said Shishi Luo, associate director of bioinformatics at Helix, a gene sequencing company which has been assisting the CDC with tracking the gene changes of SARS-CoV-2, the virus that causes Covid-19.
Based on the mix of samples Helix receives, Luo says, it has seen a 30% to 40% increase in cases since June. But because cases were already at such a low level when they started to rise, Luo says that even with this upturn, we are still in pretty low-level territory compared with some previous spikes.
“I do see some early signs that we are heading into another wave. Of course, we don’t know what lies ahead. So it may yet peter out,” said Caitlin Rivers, an assistant professor in the Department of Environmental Health and Engineering at the John Hopkins Bloomberg School of Public Health.
Rivers notes that the tea leaves are particularly hard to read this time around because laboratory testing and other data collection have been dramatically scaled back since the US ended its public health emergency for Covid-19 in May. She notes that the last time we had so little information on how the virus was spreading was in 2020.
“It doesn’t seem to be driven by a new variant, which I find encouraging,” Rivers said.
Viral levels plateau in wastewater
As testing data has become more limited, wastewater surveillance can offer a more consistent view of transmission trends over time. Data from Biobot Analytics, a biotechnology firm that has partnered with the CDC, shows that the concentration of coronavirus particles in sewage samples is about a third of what it was at this time last year.
And the amount of virus found in wastewater is growing at a much slower pace than it was a few weeks ago, suggesting a plateau in transmission, said Newsha Ghaeli, president and co-founder of Biobot.
“I wouldn’t say that in every instance a plateau has immediately led to a downturn. But we do typically see decreases once we hit a plateau,” she said, and that has been the trend in prior summers.
Covid-19 isn’t the only possible cold culprit this summer, either. CDC data suggests that a number of other pathogens that can cause flu-like symptoms or stomach bugs – including adenovirus, norovirus and rotavirus – are circulating at much higher levels this summer than they were last year.
The CDC is also tracking a slew of co-circulating Covid-19 variants, and all of them seem to be second- or third-generation offshoots of the recombinant variant XBB, each one carrying slight genetic tweaks that make them slightly fitter and more contagious.
But these gradual tweaks to the virus have been expected. There hasn’t been the kind of out-of-the-blue evolutionary leap that produced the Omicron wave, though many experts think there’s a decent possibility that we could see another game-changing variant like that one within the next couple of years.
Human behavior drives the increase
Instead, this increase seems to be driven by human behavior. More people are traveling this summer, sending them outside their normal social circles, which helps viruses find new hosts when vacationers return home with unintended souvenirs.
Then there’s the record-breaking heat, which is probably sending more people to congregate indoors for prolonged periods in search of air conditioning.
Finally, immunity has waned. US vaccination numbers suggest that it has been a while since most Americans have had a Covid-19 booster, and with cases apparently so low, antibody protection from previous infections has probably waned, too.
“Waning immunity clearly is going to play a role in all of this, and we’ve seen this over and over again, is the further out you get, even while there still is some protection against death and serious illness, waning immunity could be important in terms of the number of people who get sufficiently ill to require hospitalization,” said Michael Osterholm, an infectious disease expert who runs the Center for Infectious Disease Research and Policy at the University of Minnesota.
This is the fourth summer that Covid-19 cases have risen in the United States, and Rivers says she’s pretty convinced that this may just be what living with the virus looks like from now on.
“I’m feeling like summer and winter will be what we expect going forward,” she said.
Advice for managing a summer wave
Rivers said she’s not wearing a mask out in public because cases are still so low, but if the numbers tick up, she would.
“But if I’m traveling on an airplane or I’m getting on the metro, I would definitely want my mask on,” she said.
Rapid testing continues to be a good idea, too. Experts say that testing when you feel unwell or before you go to a crowded indoor event can help protect those who may be most vulnerable in your life, the elderly and immunocompromised.
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If you’re one of the many Americans who still haven’t gotten a bivalent booster, it might feel tempting to get one now.
Osterholm thinks it might be a good idea to wait until the new boosters targeting the XBB variant come out in September.
“I want to get the new booster,” he said. “I think the evidence is that the protection of the previous bivalent booster has been reduced over time. So that if you get it now, though, that’ll hold you back timewise from getting the new booster that hopefully will be out in the next 60 to 80 days.
“I could get infected in that time period. But I really think that that vaccine is going to be a much better vaccine in terms of long-term protection, so I want to get it as soon as it comes out,” Osterholm said.