Summer Temperatures Are Rising — And So Are Covid-19 Cases

A trio of new variants — KP.3, KP.2 and LB.1 — is fueling a nationwide surge in Covid-19 cases, with the Centers for Disease Control and Prevention reporting an increase in the rates of test positivity (up 1.2%), emergency department visits (14.7%), hospitalizations (25%) and death (16.7%) in the most recent week. This has many asking, “Why are we experiencing a summer surge and what can I do to stay safe?”

Why Are Covid-19 Cases Increasing?

Between December 2023 and May 2024, the JN.1 variant — a descendant of the Omicron strain — was the predominant cause of Covid-19 cases in the nation. However, over the past two months, three new subvariants (referred to by some as FLiRT) have emerged from JN.1 and now account for over 70% of cases. These subvariants — KP.3, KP.2 and LB.1 — possess several mutations in the gene encoding for the spike protein, which is targeted by antibodies generated by Covid-19 vaccines.

These mutations allow KP.3, KP.2 and LB.1 to more effectively evade the immune system, and potentially spread more efficiently. For those who received their last vaccination in 2023 or experienced a natural infection more than 6 months ago, it’s less likely that their immune system will ward off infection by one of the new variants. This gap in specific immunity against KP.3, KP.2 and LB.1 is helping drive the summer surge in Covid-19 cases.

Are The New Covid-19 Subvariants Causing More Severe Disease?

Fortunately, there is no evidence to suggest that infection with KP.3, KP.2 and LB.1 is associated with worse symptoms. Most infected individuals experience similar symptoms caused by past Covid-19 variants, including a sore throat, fever, cough, body aches and fatigue.

However, as the number of infections rise, so does the possibility that highly susceptible individuals — such as the elderly and immunocompromised — may contract the virus and develop severe disease. These individuals may experience difficulty breathing, which may require hospitalization.

Three Steps To Help Keep You Safe the Remainder of 2024

Despite the summer surge in Covid-19 cases, there are steps you can take to keep yourself and those around you safe. First, if you’re feeling ill, stay home and take a Covid-19 antigen test. If it’s positive, you likely have Covid-19 and should stay away from others until your symptoms have resolved. If the home antigen test is negative, consider getting a lab-based test for Covid-19. The good news is that home antigen tests, as well as lab-based tests, should continue to detect the new subvariants.

Second, if you’re hosting a summer gathering, try to have it outdoors. The virus is less likely to spread in outdoor, well-ventilated spaces. And if high temperatures force the party indoors, consider asking your guests to take a Covid-19 antigen test prior to arriving.

Finally, get an updated vaccine this fall. The Food and Drug Administration recently advised vaccine manufacturers to target the JN.1 lineage, and if possible the KP.2 subvariant, in the upcoming vaccine formulation. These new vaccines should be available this fall, and will generate a more specific antibody response against recently circulating strains. Vaccination remains the best tool we have to prevent infection, and most importantly, severe disease.