Stressed people are hit hardest by COVID-19, the flu - study

This is the first study to show how specific parts of the brain control the body’s cellular immune response while under acute stress and fighting an infection.

 A man clutches his head as he suffers from a headache and stress (Illustrative) (photo credit: MAXPIXEL)
A man clutches his head as he suffers from a headache and stress (Illustrative)
(photo credit: MAXPIXEL)

The last two years have been incredibly stressful — from a pandemic that has killed some 15 million people according to World Health Organization estimates, to fear of nuclear war and increased mass shootings. A new study says the added stress could be another preexisting condition that makes infections like COVID-19 worse.

How does acute stress affect the ability to fight?

The peer-reviewed research, conducted at Mount Sinai School of Medicine in New York and published in Nature, found that in mice, acute stress can be detrimental to fighting off infection, especially COVID-19, and increases the likelihood of dying. 

The study, which is the first to display how specific parts of the brain control the body’s cellular immune response while under acute stress and fighting an infection, looked at groups of relaxed and stressed mice and analyzed their immune systems. According to the research, within minutes, mice experiencing acute stress showed significant changes in their immune system when compared to the relaxed mouse group. 

 Health care worker takes swab samples from Israelis at a covid-19 drive through testing complex in Modi'in, February 1, 2022. (credit: YOSSI ALONI/FLASH90) Health care worker takes swab samples from Israelis at a covid-19 drive through testing complex in Modi'in, February 1, 2022. (credit: YOSSI ALONI/FLASH90)

Researchers went on to analyze how mice in the relaxed and stressed models compared when infected with influenza and COVID-19. They noticed that mice in the relaxed group did better when compared to the stressed group – they fought infection better and recovered from the virus more easily. Mice in the stressed group were sicker, had less immunity, and had a higher rate of death. 

The significance of the findings

The investigators expressed hope that the findings will lead to interventions to not just live a healthier and less stressful lifestyle, but also to help the body better fight infection and improve outcomes, in addition to encouraging doctors to look further into the mental state of their patients. 

Filip Swirski, PhD, director of the Cardiovascular Research Institute at the Icahn School of Medicine at Mount Sinai and author of the study, said the findings show just how significant the impact of stress is on the immune system. 

“This work tells us that stress has a major impact on our immune system and its ability to fight infections. It raises many questions about how socioeconomic factors, lifestyle, and environments we inhabit control how our bodies can defend themselves against infection," he said. 

"Moving forward, we will need to better understand the long-term effects of stress. It will be particularly important to explore how we can build resilience to stress and whether resilience can diminish stress’s negative effects on our immune systems.”

The long-lasting effects of stress

An Israeli study conducted in 2021 found that stress and anxiety has increased as a result of the pandemic, with the crisis leaving psychological and emotional scars that could have long-lasting and wide-ranging effects.

A small team of researchers from the Weizmann Institute of Science developed a questionnaire dedicated to the mental and emotional effects of COVID-19, which they distributed over six weeks, between the end of the first wave in Israel and the beginning of the second – late April to early June 2020.

Nearly 5,000 Israelis answered the digital survey, which used clinically validated instruments to assess anxiety- and depression-related emotional distress, symptoms and coping strategies. It also evaluated how changes in the pandemic’s dynamics affected emotional well-being.

The results showed increased stress levels among most respondents, with women, young adults and people who became unemployed as a result of the crisis being the hardest hit. 

Maayan Jaffe-Hoffman contributed to this report.