Is There a Link Between a Low White Blood Cell Count and COVID?

Having a low white blood cell (WBC) count, also known as leukopenia, means that your body is not making enough of these immune system cells that help fight off infections. A number of conditions and certain medications can cause a low white blood cell count.

White blood cells defend your body against foreign pathogens. Therefore, having a low WBC count puts you at a higher risk of contracting infections, which recent research has shown includes coronavirus disease 2019 (COVID-19). In this article, we'll discuss the link between the two and how white blood cells are affected by COVID.

What Are White Blood Cells?

White blood cells are a type of immune cell. They are created in the bone marrow, the spongy part of your bones, and can be found in blood and in tissues that support the immune system, which are known as lymph tissues. There are several types of white blood cells, and each plays a role in fighting infection and disease in the body:

• Granulocytes, including neutrophils, eosinophils, and basophils, which are released during allergic reactions and asthma
• Monocytes, which help fight off infections and facilitate healing
• Lymphocytes, including T-cells and B cells, while help control immune responses

Your WBC count is measured with a blood test called a complete blood count (CBC). If your WBC count is higher than normal, this could indicate an infection or inflammation. A low WBC count signals a problem with your immune system. This is a common problem in people living with cancer or taking medications that suppress the immune system.

Typical reference ranges for a WBC count are:

• Low: Less than 4,500 WBCs per microliter
• Normal: 4,500 to 11,000 WBCs per microliter
• High: More than 11,000 WBCs per microliter

The Connection Between White Blood Cell Count and COVID-19

A high WBC count, also called leukocytosis, is usually a sign that the body is fighting an infection, and the same is true in COVID-19. Research has shown that people who test positive for COVID-19 but have no symptoms typically have a high WBC count, particularly lymphocytes.

Lymphocytes circulate throughout your body, and create antibodies, proteins released to fight pathogens, to help your immune system fight infections. B cells focus on attacking invading viruses and bacteria, while T-cells destroy the body's own cells that have been damaged by things like viruses or cancer.

The high level of lymphocytes observed in asymptomatic people with COVID-19 makes sense. It means that their immune systems are doing a good job of keeping the coronavirus in check by creating antibodies and destroying damaged cells.

Studies have shown more severe illness and death in people with COVID-19 who had a high WBC count. A number of other studies have found that lower WBC counts or elevated WBC counts with decreased levels of lymphocytes in particular were associated with more severe illness and death in COVID-19.

This can be because the levels of some types of WBCs like neutrophils are higher as the body fights off the virus, while levels of lymphocytes remain low.

Symptoms of COVID-19

The symptoms of COVID-19 and a low WBC count are quite different. COVID-19 symptoms can include:

• Fever
• Chills
• Cough
• Shortness of breath
• Difficulty breathing
• Fatigue
• Muscle aches
• Headaches
• Loss of taste or smell
• Sore throat
• Congestion or runny nose
• Nausea or vomiting
• Diarrhea

There are no actual symptoms of a low white blood cell count, but people who have a low WBC count can develop various symptoms due to infections that their bodies are not able to fight off. People with the following conditions typically have low WBC counts:

• Autoimmune diseases, such as rheumatoid arthritis
• Cancer treatment like radiation
• Infections like HIV and hepatitis
• Antipsychotic medications
• Agranulocytosis, which is when your body doesn't make enough neutrophils
• Neutropenia, which is when your body has a low level of neutrophils

More specifically, though, people who have low levels of lymphocytes have a condition called lymphocytopenia or lymphopenia. It occurs when your body doesn't make enough of these blood cells. It can also be acquired, such as in people with AIDS.

Symptoms of diseases that can cause a low white blood cell count like HIV, cancer treatment, and uncontrolled diabetes can include:

• Frequent or repeat infections
• Infections that won't resolve
• Unusual or rare infections
• Fevers
• Bladder infections
• Mouth sores
• Skin infections
• Sinus infections or stuffy nose

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Diagnosis and Treatment of COVID-19

A diagnosis of COVID-19 is confirmed with two tests:

• A viral test indicates if you have a current infection.
• An antibody test can show if you had a past infection.

The Centers for Disease Control and Prevention (CDC) recommends that anyone with symptoms of COVID-19 or who has been directly exposed to someone who is positive for COVID be tested for the virus.

There is only one medication approved by the Food and Drug Administration to treat COVID-19 at the moment: Veklury (remdesivir). However, it is reserved for the treatment of hospitalized people over the age of 12. There are multiple other medications that have Emergency Use Authorization, such as Actemra (tocilizumab).

Generally, hospitalized patients with COVID-19 are treated with remdesivir or dexamethasone or similar corticosteroids if they require supplemental oxygen. You may also be treated with blood thinners to control blood clotting.

People who are dealing with the virus at home should monitor their symptoms and stay in touch with their doctors if they are concerned. You should head to the emergency department or call 911 if you have trouble breathing or your symptoms suddenly become worse.

Overall, you will want to:

• Use over-the-counter medications like Tylenol (acetaminophen) to manage fever and other symptoms.
• Drink plenty of fluids.
• Get rest.
• Wear a mask if you have to be around others.
• Wash your hands frequently.
• Avoid sharing utensils or personal items with others.
• Clean shared surfaces frequently.

Ways to Prevent COVID-19 or Infections

There may not be many ways to prevent having a low blood count. Typically, a low WBC count is the result of an infection or a condition, or of a medication that you need.

You can, however, take steps to protect yourself against COVID-19, and you should be extra vigilant with these steps if you know you have a low WBC count. Usually, people with low WBC counts are educated on how to prevent an infection, and much of that guidance mirrors the strategies to avoid COVID-19, such as:

• Wear a mask.
• Wash hands frequently.
• Avoid large crowds, especially indoors.
• Avoid people who are sick.
• Clean and disinfect the areas around you frequently.

Unlike with some other infections like HIV, you can also be vaccinated against COVID-19. Recent spikes in infection have proven the effectiveness of the vaccine, with far more unvaccinated people being hospitalized with the virus than vaccinated people.

Summary

Having a low white blood cell count means you are at higher risk of infections because WBCs help fight pathogens in your body. You can have a low WBC count due to a condition or infection or medications you are taking. Recent research has shown that people with a low WBC count are more likely to have a severe case of COVID-19. You should practice prevention strategies against COVID-19 vigilantly if you have a low WBC count.

A Word From Verywell

Your white blood cells power your immune system, and lower cell counts can prove deadly in the case of a major infection. Low white blood cell counts have been found to contribute to severe disease and death in people with COVID. While you may not be able to prevent a low WBC count, you can take steps to prevent a COVID infection.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.