Many of us have experienced the death of a loved one and the grief that inevitably accompanies it. Such loss is widely considered to be the most stressful event we will ever encounter in our lives. I have been thinking about this lately because in just a few months it will be five years since my wife died from brain cancer.

Since March 2020, more than 600,000 Americans have died from COVID-19, with more dying each day. It has been estimated that each person who died from COVID-19 leaves nine people bereaved. That means that in the U.S. alone, at least 5 million people are having to find their own way through the grief that follows.

Grief is often thought of as just a psychological process. But it is much more than that. The death of a loved one has a profound effect on our bodies in addition to our minds.

People who are grieving the loss of a spouse or other loved one have a higher risk of dying from any cause in the six months following the death of their family member. This is higher than other well-known risk factors such as smoking. In the first 24 hours following the death of a significant other, the surviving life partner is 20 times more likely to have a heart attack. This risk gradually declines over the next three to six months. At the one-year mark after experiencing a loss, the risk of dying is still 25% higher than for those who have not suffered a loss.

These statistics may sound scary and morbid, but they emphasize the fact that the loss of a loved one can have negative effects on a person’s health. The reasons for this are still not fully understood. However, one of the earliest studies to examine the biological effects of grief showed that spouses’ immune systems did not function properly for up to six weeks after their partner died.

Chronic stress such as bereavement may lead to a depressed immune system and increased inflammation. One study found that people who experienced more severe symptoms of grief had more inflammation than those with less severe symptoms. The combination of an impaired immune system and increased inflammation has been linked to autoimmune disorders, cancer and, in some cases, blood clots that can increase the risk of heart attack or stroke. The stress of grieving has also been shown to affect parts of the nervous system that regulate heart rate and blood pressure, which also contributes to the development of heart disease.

Psychological stress can make us build fewer antibodies in response to vaccinations. This could be particularly important to remember as the focus remains on vaccinating people as a way to end the COVID-19 pandemic.

While we hope that the worst of the COVID-19 pandemic may be over in the U.S., there is no doubt that we are still at the beginning of dealing with its many long-term effects.