Covid-19 cases are climbing again this summer, with the Centers for Disease Control and Prevention’s (CDC) forecasting model indicating that infections are growing in most states. Although national wastewater data shows low virus levels, some states, including Texas, Utah, and Nevada, have very high concentrations. Emergency department visits linked to Covid are also increasing. Researchers had anticipated this uptick, as Covid cases have risen every summer since the pandemic began. However, this current wave appears to be milder than the one observed around the same time last year.
The “Nimbus” Variant
As of the CDC’s last update in June, the dominant variant in the United States is NB.1.8.1., nicknamed “Nimbus,” accounting for about 43% of cases. According to infectious disease epidemiologist Dr. Aubree Gordon, this variant doesn’t seem to cause more severe illness than other recent strains. However, it does have a few additional mutations that may make it more transmissible and better at evading the immune system’s defenses. Dr. Ziyad Al-Aly, a senior clinical epidemiologist, describes the current situation as a “late summer upswing” rather than a full-on surge, noting that “the numbers are very clearly going up.”
Why Summer Spikes Occur
Scientists have identified several reasons for the predictable summer spread of the virus:
- Indoor Gatherings and Poor Ventilation: While people spend more time outdoors in warm weather, the heat also drives them inside to air-conditioned spaces with closed windows. Poor ventilation in these indoor environments, combined with the fact that the virus survives longer in colder environments, makes it easier for Covid to spread.
- Summer Travel and Crowds: Increased travel during the summer, particularly around holidays like the Fourth of July, creates a “ripe breeding ground” for the virus. Crowded places like airports, trains, and even outdoor events like music festivals can facilitate transmission as people inhale respiratory droplets from infected individuals.
- Waning Immunity: Covid, like many respiratory viruses, also tends to surge in the winter. The immunity from a winter infection or vaccination typically lasts four to six months. By summer, this immunity can wane, making people susceptible to getting sick again.
What to Do: Test and Be Aware
Since Covid strikes more often in the summer than other respiratory viruses with similar symptoms, Dr. Al-Aly advises people who feel sick to take a Covid test. He also emphasizes the importance of getting vaccinated, though the availability of updated vaccines this year is currently unclear. While the rising case numbers aren’t a “panic situation,” he recommends that people “be aware that numbers are now higher than they were a couple months ago.”
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Source: The New York Times
