COVID keeps roaring back in the summer

Travel, air-conditioned environments and waning immunity from shots may be factors

- RONG-GONG LIN II

PHARMACIST Deep Patel prepares Brandon Guerrero's vaccine at CVS in 2024.

By many measures, the coronavirus is a thing of the past.

Masks have been stored away. Social distancing is just a vague memory. Interest in vaccines is waning. COVID, for many, feels like an inevitable annoyance, like the flu.

Then, each summer, we get a rude reminder.

The season of travel and fun continues to bring a spike in COVID-19 activity, far less profound than during the height of the pandemic but enough for people to notice and worry.

This summer's jump is being fueled by the subvariant XFG, nicknamed “Stratus.”

“As we learn more about COVID, we are seeing that it has two surges a year: the late fall/early winter and in the summer, so we expect this trend of increased cases in the summer to continue,” said Dr. Elizabeth Hudson, the regional chief of infectious disease at Kaiser Permanente Southern California.

Why summer?

There are a number of factors that could explain why COVID activity seems to ramp up along with the temperature, according to the Los Angeles County Department of Public Health:

• Summertime travel and increased social mixing because of social events.

• Spending time indoors to beat the heat: Respiratory viruses tend to spread more easily in environments with low humidity and cool temperatures. Air-conditioned spaces might not have adequate ventilation.

• Waning immunity from vaccination and previous infections.

• Mutations: As the virus spreads, it acquires mutations that allow it to evade our existing immunity. Eventually, a version of the virus collects enough mutations that it has a slight edge over other viruses, and if other factors line up, it can sweep through a population.

What do the numbers show?