As the weather becomes hotter during the summer months, more people travel and congregate in indoor spaces to escape the heat. As a result, the summer months can be a time when viruses circulate more easily and people fall ill. Summer also comes with more heat-related illnesses and injuries. Take a look at trends in summer illnesses in 2023.
In the summer of 2023, there has been an upward trend in the number of cases of upper-respiratory illnesses caused by COVID-19, enteroviruses, and human metapneumovirus, as well as heat-related illnesses exacerbated by climate change.
Since late June of 2023, there has been a moderate increase in COVID-19 cases, according to data from pharmacy-based testing and health system-based testing (4). Although this trend has been relatively low compared to previous spikes, cases have risen by 30-40% since June, accompanied by a rise in hospitalizations (4). COVID cases trended trending upward in the South, Northeast, West, and Midwest regions of the United States (5). This rise in cases during the summer can be attributed to an increase in travel and a rise in indoor activities driven by heat, as well as waning immunity to the virus. Most 4Americans have not received a COVID-19 booster in many months, and immunity from both infection and vaccination usually lasts three to six months at most (5). As a result, people who were infected by Covid-19 or received a booster last winter became more susceptible to the virus. A new booster vaccine for the XBB.1.5 variant will be released in the fall of 2023, potentially helping to improve overall immunity (5).
Data from the CDC also indicates that other viruses spread at a faster rate this year compared to the summer of 2022. In particular, viruses that cause flu-like symptoms or gastrointestinal symptoms, including adenovirus, norovirus, and rotavirus, have seen an increase in the number of cases since spring (4). Human metapneumovirus or HMPV spiked this year in March 2023, with 11% of PCR lab tests indicating a positive result for the virus (3). Prior to the pandemic, the highest number of positive results for HMPV had been significantly lower at 7% (3). Furthermore, the number of pediatric hospitalizations due to rhinovirus and other enterovirus illnesses rose last year, with similar patterns expected for late summer in 2023 (6). Rhinoviruses and other enteroviruses usually peak in late summer and early fall and can cause severe respiratory illness in children and the elderly (6).
Additionally, record high rates of heat-related illnesses and deaths have been recorded throughout the country in summer 2023. In the Northeast, upper Midwest, and Rocky Mountain regions, hospitals recorded the highest rates of heat-related illnesses in five years this April (2). Similarly, heat-related illnesses spiked in the Southern region of the United States in June, when the rate of emergency visits for heat-related illnesses reached the highest number in five years (2). The number of heat-related illnesses and deaths rises each summer due to ongoing climate change. Young children, the elderly, people who are pregnant, and people with respiratory conditions are particularly vulnerable to heat stroke during these times.
References
- Goodman, Brenda and Deidre McPhillips. “Your recent cold could be Covid-19, as the nation goes into a late summer wave.” CNN Health, 28 July 2023, www.cnn.com/2023/07/28/health/summer-cold-covid-19/index.html
- Huang, Pien et al. “This CDC data shows where rates of heat-related illness are highest.” NPR, Shots Health News, 26 July 2023, https://www.npr.org/sections/health-shots/2023/07/26/1190085775/this-cdc-data-shows-where-rates-of-heat-related-illness-are-highest
- “Human Metapneumovirus (HMPV) National Trends.” Center for Disease Control and Prevention, The National Respiratory and Enteric Virus Surveillance System (NREVSS), 22 Aug 2023, https://www.cdc.gov/surveillance/nrevss/hmpv/natl-trend.html
- Murez, Cara. “As a Summer Surge of COVID Takes Hold, Don’t Mistake It for a Cold.” US News and World Report, HealthDay, 31 July 2023, https://www.usnews.com/news/health-news/articles/2023-07-31/as-a-summer-surge-of-covid-takes-hold-dont-mistake-it-for-a-cold
- Prater, Erin. “Has COVID-19 become a summer illness? Cases and hospitalizations are on the rise again.” Fortune, 28 July 2023, https://fortune.com/well/2023/07/28/does-covid-spike-summer-rise-cases-hospitalizations-us/
- “Severe Respiratory Illnesses Associated with Rhinoviruses and/or Enteroviruses Including EV-D68—Multistate, 2022.” Center for Disease Control and Prevention, Emergency Preparedness and Response, 9 Sept 2022, https://emergency.cdc.gov/han/2022/han00474.asp