Having a low white blood cell (WBC) count, also known as leukopenia, means that your body is not making enough of the immune cells it needs to fight invaders (pathogens) like bacteria and viruses. A low WBC count puts you at risk of infections, including coronavirus (COVID-19) infections. Research has found that having fewer lymphocytes, a type of white blood cell, can be a risk factor for severe cases of COVID.
This article discusses the link between a low white blood cell count and COVID. It also explains how white blood cells are affected by COVID.
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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, are released during allergic reactions and asthma
- Monocytes help fight off infections and facilitate healing
- Lymphocytes, including T-cells and B cells, help control immune responses
Your WBC count is measured with a blood test called a complete blood count (CBC). The results are reported as WBCs per microliter (µL). 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.
The table below shows the normal ranges of WBC counts. Anything below these ranges is considered low.
| WBCs (per µL) | |
|---|---|
| Men | 5,000 to 10,000 |
| Women | 4,500 to 11,000 |
| Children | 5,000 to 10,000 |
An Overview of White Blood Cell Disorders
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 at hospital admission. But a number of other studies have found that lower WBC counts or elevated WBC counts with decreased levels of lymphocytes in particular were also 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.
What Are the 5 Types of Antibodies?
Symptoms of COVID-19
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
A low white blood cell count doesn't cause any symptoms on its own, 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
COVID-19 Doctor Discussion Guide
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Diagnosis and Treatment of COVID-19
A diagnosis of COVID-19 is confirmed with two kinds of 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 take precautions to prevent spread and get tested if at risk for severe illness.
If you have symptoms of COVID-19, you will need to follow steps to protect the people around you. The CDC recommends staying home and away from others until your symptoms improve for 24 hours without taking fever-reducing medications. After that, you may resume normal activities but should take precautions, like wearing a mask and physically distancing, for the next five days.
There are two medications approved by the Food and Drug Administration to treat COVID-19 in hospitalized people at the moment: Veklury (remdesivir) andActemra(tocilizumab). Veklury is approved for the treatment of people aged 28 days and older who require hospitalization or are nonhospitalized and at high risk of severe COVID-19 progression.
Actemra is approved for the treatment of hospitalized adults aged 18 and over who are receiving systemic corticosteroids and require supplemental oxygen, non-invasive or invasive mechanical ventilation, orextracorporeal life support (ECMO). Actemra also has Emergency Use Authorization for people ages 2 years and older.
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 healthcare providers if they are concerned. The COVID-19 Treatment Guidelines Panel recommends the following antiviral treatments for nonhospitalized adults:
- Paxlovid (nirmatrelvir and ritonavir)
- Veklury (remdesivir)
- Lagevrio (molnupiravir)
Molnupiravir vs. Paxlovid: Which Is Better for COVID-19?
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.
- Isolate at home.
- 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 condition or 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 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
You should also stay up-to-date with COVID-19 vaccines. 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.
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 ourcoronavirus news page.
19 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rachael Zimlich, BSN, RN
Zimlich is a critical care nurse who has been writing about health care and clinical developments for over 10 years.
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