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If you are at higher risk

January 19, 2022

How to reduce risk of infection and what to do if you get sick

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Who is at highest risk for getting very sick from COVID-19?

The risk of serious illness from COVID-19 increases steadily with age, especially for those with underlying medical problems. According to the CDC, adults of any age with the following conditions can be more likely to get severely ill from COVID-19:

Visit our Coronavirus Resource Center for more information on coronavirus and COVID-19.

  • Cancer, cancer treatment, and history of cancer
  • Chronic kidney disease
  • Chronic lung diseases, including COPD (chronic bronchitis or emphysema), asthma (moderate to severe), damaged or scarred lung tissue, cystic fibrosis, and pulmonary hypertension
  • Dementia or other neurological conditions
  • Diabetes (type 1 or type 2)
  • Down syndrome
  • Heart conditions, such as heart failure, coronary artery diseases, or cardiomyopathies (diseases of the heart muscle that make it harder for the heart to pump blood to the rest of your body), or high blood pressure (hypertension)
  • HIV (human immunodeficiency virus) infection
  • Immunocompromised state (weakened immune system), including from inherited conditions or prolonged used of corticosteroids or other immune-weakening medicines
  • Liver disease, including alcohol-related liver disease, nonalcoholic fatty liver disease, cirrhosis, or scarring of the liver
  • Overweight and obesity (body mass index [BMI] of 25 or higher)
  • Pregnancy
  • Sickle cell disease, thalassemia, or other hemoglobin blood disorders
  • Smoking, current or former
  • Solid organ or blood stem cell transplant, including bone marrow transplant
  • Stroke or cerebrovascular disease, which affects blood flow to the brain
  • Substance use disorders such as alcohol, opioid, or cocaine use disorder

According to the CDC, hospitalizations have been six times higher and deaths 12 times higher among those with reported underlying conditions compared with those who did not have underlying health conditions.

A study published in the Journal of the American Heart Association found that among the more than 900 000 people hospitalized for COVID-19 in the US through November 2020, nearly two-thirds (63.5%) were attributable to four conditions: obesity, hypertension, diabetes, and heart failure. In other words, these hospitalizations might not have occurred if these conditions had not been present. For all conditions, risk increased with age. And within any age group, COVID‐19 hospitalizations attributable to each medical condition were higher in Black compared with White adults.

Everything we know underscores the importance of maintaining health-promoting behaviors, even as restrictions begin to ease, especially if you have an underlying medical condition. To reduce your risk of getting sick, get vaccinated as soon as you are eligible, wear a mask, maintain a physical distance of at least six feet when you're around other people, and wash your hands often.

Everything we are learning underscores the importance of maintaining health-promoting behaviors, even as restrictions begin to ease, especially if you have an underlying medical condition. To reduce your risk of getting sick, get vaccinated as soon as you are eligible, wear a mask (especially indoors and especially if you live in or visit an area of the country with widespread transmission), and wash your hands often.

In August 2021, the FDA authorized a third dose of mRNA vaccine (Pfizer/BioNTech or Moderna) for certain immunocompromised people. A person with a weakened immune response is more likely to have a breakthrough infection, and is at increased risk of more severe disease if they do become infected. A third vaccine dose may enhance the immune response in some people who are immunocompromised. Talk to your doctor if you think you may qualify for a third COVID vaccine dose.

I have a weakened immune system. Do I need a third dose of the COVID-19 vaccine?

The CDC recommends a third dose of an mRNA COVID-19 vaccine for adults and children ages 5 years and older who are moderately to severely immunocompromised. The third dose should be given at least 28 days after the second dose. The COVID-19 vaccines, like other vaccines, work by stimulating a person’s immune system to produce antibodies against the virus. If the antibodies later encounter the actual virus, they are ready to recognize and destroy it.

A person with a weakened immune system may not be able to produce a strong enough immune response to the standard, two-dose COVID mRNA vaccine regimen. This leaves them more likely to have a breakthrough infection, and increases the risk of more severe disease if they do become infected. A third vaccine dose may enhance the immune response in some people who are immunocompromised.

A person may have a weakened immune system for a variety of reasons. These include being born with an immunodeficiency, having advanced or untreated HIV, and having a chronic medical condition such as chronic kidney disease or lack of a spleen. Many types of medication also suppress the immune response, including some cancer treatments, TNF blockers, some biologic agents, and high-dose corticosteroids. Talk to your doctor if you think you may qualify for a third COVID vaccine dose.

Anyone with a weakened immune system should continue to wear masks, stay six feet apart from others, and avoid crowds and poorly ventilated indoor spaces.

Who could benefit from monoclonal antibody therapy to prevent COVID-19?

Vaccines are the best way to protect against COVID-19. But some people with weakened immune systems do not produce enough antibodies after vaccination, and others are severely allergic to the vaccine. The FDA recently authorized Evusheld, a pre-exposure prophylaxis (PrEP) monoclonal antibody therapy developed by AstraZeneca, which should help prevent COVID-19 in these populations.

To be eligible for Evusheld, individuals must be 12 years or older and have a moderately to severely weakened immune system, or have a history of severe adverse reactions to the COVID-19 vaccine or its components. In addition, the therapy cannot be given to someone with a current SARS-CoV-2 infection, or who has been recently exposed to someone who is infected. Evusheld is given as two consecutive shots, and evidence suggests it can help prevent symptomatic infection for at least six months.

Monoclonal antibodies are manmade versions of the antibodies that our bodies naturally make to fight invaders, such as the SARS-CoV-2 virus. The monoclonal antibodies in Evusheld, tixagevimab and cilgavimab, are directed against the virus’s spike protein and are designed to block the virus from attaching to, and entering, human cells.

When considering authorization, the FDA looked at results from the PROVENT trial. This was a randomized, double-blind, placebo-controlled clinical trial that enrolled adults ages 59 years and older, people with certain chronic medical conditions, and those who were at increased risk of infection for other reasons and had not gotten a COVID-19 vaccine. None of the participants had a current or previous case of SARS-CoV-2 infection. 3,441 study participants received Evusheld and 1,731 received a placebo.

Study participants who’d received Evusheld were 83% less likely to have had symptomatic COVID-19 during the six-month study period than those who had a received a placebo. This was a statistically significant difference. Researchers are looking at how well Evusheld will protect against the Omicron variant.

Possible side effects of this therapy including allergic reactions, bleeding at the injection site, headache, fatigue, and cough. In addition, although serious heart-related events such as heart attack and heart failure were infrequent during the trial, they were more common in participants who received Evusheld than in those who received a placebo.

Unlike other monoclonal antibody treatments that have been authorized by the FDA, Evusheld is not authorized to treat an active COVID-19 infection or to prevent infection after exposure to the virus.

Who can get a COVID-19 vaccine booster shot?

The CDC recommends a single-dose COVID-19 vaccine booster for all adults ages 18 years and older. Those who initially received the Pfizer/BioNTech mRNA vaccine can get their booster five months after their second shot; those who received the Moderna mRNA vaccine can get their booster six months after their second shot, and those who received an initial dose of the Johnson & Johnson vaccine can get a booster dose two months after their initial vaccine. Adults may select any vaccine for their booster, either the same (homologous) or different (heterologous) than their initial vaccine(s). However, the CDC has stated a preference for either of the mRNA vaccines over the Johnson & Johnson vaccine.

The CDC also recommends a single-dose Pfizer/BioNTech COVID-19 booster shot for children ages 12 to 17 years, at least five months after getting their second dose of that vaccine. As of now, individuals in this age group are only authorized to receive the Pfizer/BioNTech vaccine.

Which COVID-19 vaccine booster should I get?

Adults ages 18 years and older may select any COVID-19 vaccine (Pfizer/BioNTech, Moderna, or Johnson & Johnson) for their booster, either the same as (homologous) or different than (heterologous) their initial vaccine(s).

The FDA’s mix-and-match authorization makes booster shots less dependent on which vaccines are available and gives people more choices. For example, if you had an unpleasant reaction to your initial vaccine, you could choose a different one for your booster. Or, if you don’t remember which vaccine you started with, you can still get a booster.

Although Johnson & Johnson’s vaccine is still available, the CDC has stated a preference for one of the mRNA COVID-19 vaccines over Johnson & Johnson’s vaccine. This recommendation was based on growing evidence that Johnson & Johnson’s vaccine increases the risk of blood clots. Although very rare, this problem can be serious and even lead to death.

The CDC also recommends boosters for children ages 12 to 17 years. Right now, only the Pfizer/BioNTech vaccine is authorized for this age group.

I'm older and have a chronic medical condition, which puts me at higher risk for getting seriously ill, or even dying from COVID-19. What can I do to reduce my risk of exposure to the virus?

The risk of serious illness or death from COVID-19 increases steadily with age. This is true whether or not you also have an underlying medical condition, although the sickest individuals and most of the deaths have been among people who were both older and had chronic medical conditions, such as heart disease or diabetes.

The CDC suggests the following measures for those who are at higher risk:

  • Get vaccinated as soon as you are eligible.
  • Keep at least six feet of space between yourself and others outside of your household.
  • When you go out, wear a mask, keep away from others who are sick, limit close contact, and wash your hands often.
  • Avoid crowds.
  • Avoid nonessential travel.
  • During a COVID-19 outbreak in your community, stay home as much as possible to further reduce your risk of being exposed.
  • Obtain several weeks of medications and supplies in case you need to stay home for prolonged periods of time.

In August 2021, the FDA authorized a third dose of mRNA COVID-19 vaccine (Pfizer/BioNTech or Moderna) for certain people with a weakened immune response. If your medical condition or treatment for that medical condition impacts your immune response, ask your doctor if you qualify for a third COVID vaccine dose.

Have the COVID vaccines effectively protected older adults in the real world?

Two reports published in MMWR in September 2021 found that vaccine protection has declined in older adults. However, vaccinated older adults still enjoy significant protection compared to older adults who are unvaccinated.

One report describes the results of a study looking at the effectiveness of the COVID vaccines (Pfizer/BioNTech, Moderna, and Johnson & Johnson) in preventing COVID-related hospitalization at five Veterans Affairs Medical Centers in the US. It found that vaccines were 80% effective in preventing COVID-related hospitalization in people aged 66 years and older compared to 95% in people aged 18 to 65 years.

The second report is an interim analysis of ongoing data collection from medical sites in nine different states. The vaccines were found to be 89% effective at preventing COVID-related hospitalization in people ages 18 to 74 and 76% in people aged 75 or older. The researchers based their findings on an analysis of 32,867 medical encounters, including visits to hospitals, emergency departments, and urgent care sites. The data collection occurred during a time when Delta was responsible for more than half of infections.

A small study conducted earlier this year by the CDC and published in MMWR reported that the two mRNA vaccines (Pfizer/BioNTech and Moderna) had been as effective in older adults in the real world as they were in the clinical trials that led to authorization of their use. That study found that full vaccination reduced risk of COVID-related hospitalization by 94% compared to 95% (Pfizer/BioNTech) and 94.1% (Moderna) in the clinical trials. At the time of this study, the Delta variant was much less common.

This newest data does suggest that Delta variant is the primary reason for the decline in vaccine effectiveness. But the numbers still strongly support vaccine efficacy even during a period of Delta dominance.

I have a chronic medical condition that puts me at increased risk for severe illness from COVID-19, even though I'm only in my 30s. What can I do to reduce my risk?

You can take steps to lower your risk of getting infected in the first place:

  • Get vaccinated once you are eligible.
  • Wear a mask indoors when you are with friends and family from outside of your household.
  • Limit contact with people outside your family.
  • Maintain enough distance (six feet or more) between yourself and anyone outside your family.
  • Wash your hands often with soap and warm water for 20 to 30 seconds.
  • Stay away from people who are sick.
  • During a COVID-19 outbreak in your community, stay home as much as possible to further reduce your risk of being exposed.
  • Avoid nonessential travel.

In addition, do your best to keep your condition well-controlled. That means following your doctor's recommendations including taking medications as directed. If possible, get a 90-day supply of your prescription medications and request that they be mailed to you so you don't have to go to the pharmacy to pick them up.

In August 2021, the FDA authorized a third dose of mRNA COVID-19 vaccine (Pfizer/BioNTech or Moderna) for certain people with a weakened immune response. If your medical condition or treatment for that medical condition impacts your immune response, ask your doctor if you qualify for a third COVID vaccine dose. And ask your doctor for additional advice specific to your condition.

How does obesity increase risk of COVID-19?

According to a review and meta-analysis that looked at 75 international studies on the subject, obesity is a significant risk factor for illness and death due to COVID-19.

When looking at people with COVID-19, the analysis found that, compared with people who were normal weight or overweight, people who were obese were

  • more than twice as likely to be hospitalized
  • if hospitalized, nearly 75% more likely to be admitted to the intensive care unit (ICU)
  • almost 50% more likely to die of COVID-19.

Obesity may impact COVID risk in several ways. For example, obesity increases the risk of impaired immune function and chronic inflammation, both of which could make it harder for the body to fight the COVID-19 infection. Excess fat can also make it harder for a person to take a deep breath, an important consideration for an illness that impairs lung function.

People who are obese are also more likely to have diabetes and high blood pressure, which are themselves risk factors for severe COVID-19. And obesity is more common in Black, Latinx, and Native Americas, who are more likely to get infected and die from COVID-19 than whites for a variety of reasons.

If you have obesity (defined as a body mass index, or BMI, of 30 or higher), stay vigilant about protecting yourself from infection. That means getting vaccinated once you are eligible, wearing a mask indoors if you live in or visit an area of the country with widespread transmission, and washing your hands often.

I have asthma. If I get COVID-19, am I more likely to become seriously ill?

The coronavirus that causes COVID-19 infection primarily attacks the upper airways and lungs. So, similar to any other respiratory infection, such as the flu or viral bronchitis, your asthma symptoms could get much worse if you get COVID-19.

However, you can take steps to lower your risk of getting infected in the first place. These include

  • getting vaccinated once you are eligible
  • physical distancing
  • wearing masks, as advised by the CDC
  • washing your hands often with soap and warm water for 20 to 30 seconds
  • staying away from people who are sick.

In addition, you should continue to take your asthma medicines as prescribed to keep your asthma under control. If you do get sick, follow your asthma action plan and call your doctor.

Do pregnant women face increased risks from COVID-19?

According to the CDC, pregnant and postpartum women are at increased risk of severe COVID-19 illness, death, and pregnancy complications compared to women who are not pregnant. In addition, COVID-19 increases risk for premature birth, stillbirth, and possibly also for other undesirable pregnancy outcomes. It's important to note that the overall risk of these complications is low. But the risk is higher than in people who are not pregnant.

Results from a large, observational study from Scotland conducted between December 2020 and October 2021 showed that risks to both mother and baby are substantially higher in pregnant women who are unvaccinated, compared to those who are vaccinated.

The CDC recommends that women who are pregnant, thinking about becoming pregnant, or who are breastfeeding should get vaccinated against COVID-19. The American College of Obstetrics and Gynecology (ACOG) and the Society for Maternal-Fetal Medicine also agree that all pregnant and breastfeeding individuals should be vaccinated.

If you are pregnant, talk to your doctor about the COVID-19 vaccine. And be vigilant about taking additional precautions as well. For example, wear a high-quality, well-fitted mask, physically distance from others, and avoid social gatherings. And do your best to follow the CDC's recommendations to protect yourself if someone in your household becomes infected.

Continue to see your doctor for prenatal visits and get any other recommended vaccines. Call your doctor's office to discuss safety precautions if you have concerns.

I am pregnant and plan to eventually breastfeed my baby. Is it safe for me to get a COVID-19 vaccine?

The CDC recommends that women who are pregnant, thinking about becoming pregnant, or were recently pregnant — including those who are breastfeeding — should get vaccinated against COVID-19. The American College of Obstetrics and Gynecology (ACOG) and the Society for Maternal-Fetal Medicine also agree that all pregnant and breastfeeding individuals should be vaccinated.

Here are some factors to consider. First, although the actual risk of severe COVID-19 illness and death among pregnant individuals is very low, it is higher when compared to nonpregnant individuals from the same age group. In addition, COVID-19 increases risk for premature birth, stillbirth, and possibly also for other undesirable pregnancy outcomes. Results from a large, observational study from Scotland conducted between December 2020 and October 2021 showed that risks to both mother and baby are substantially higher in pregnant women who are unvaccinated, compared to those who are vaccinated.

Evidence supporting the safety of COVID vaccines for pregnant women and their babies continues to grow. One study published in MMWR looked at data from more than 40,000 pregnant women between December 2020 and July 2021. About 10,000 of these women received a COVID-19 vaccine (typically an mRNA vaccine, either Pfizer/BioNTech or Moderna) during their pregnancy, most during their second or third trimester. Women who were vaccinated against COVID-19 while pregnant were no more likely than unvaccinated women to give birth prematurely or have a baby that was small for its gestational age.

A study published in NEJM in October 2021 analyzed safety data collected by the CDC. The researchers looked at data from nearly 2,500 women who received a COVID-19 vaccine, either before becoming pregnant or during their first 20 weeks of pregnancy, and found that they did not have an increased risk of miscarriage. A previous study, conducted by the CDC and published in NEJM, found the COVID-19 vaccines to be safe when given during the second or third trimester.

A small study that compared vaccine efficacy in pregnant and nonpregnant women was published in the American Journal of Obstetrics and Gynecology. The study found that mRNA vaccines effectively produce antibodies that protect against SARS-CoV-2 in women who are pregnant or breastfeeding, and that this immunity is passed from mother to newborn through the placenta and breast milk.

mRNA vaccines do not contain any virus, so they cannot cause COVID-19 in a woman or her baby. And our bodies quickly break down and eliminate mRNA particles used in the vaccine, so they cannot reach or cross the placenta.

Similar to any decision regarding over-the-counter medications and supplements during pregnancy, your own doctor is in the best position to advise you based on your personal health risks and preferences.

I'm taking a medication that suppresses my immune system. Should I stop taking it so I have less chance of getting sick from the coronavirus?

If you contract the virus, your response to it will depend on many factors, only one of which is taking medication that suppresses your immune system. In addition, stopping the medication on your own could cause your underlying condition to get worse.

Most importantly, don't make this decision on your own. It's always best not to adjust the dose or stop taking a prescription medication without first talking to the doctor who prescribed the medication.

In August 2021, the FDA authorized a third dose of mRNA vaccine (Pfizer/BioNTech or Moderna) for certain immunocompromised people. A person with a weakened immune response is more likely to have a breakthrough infection, and is at increased risk of more severe disease if they do become infected. A third vaccine dose may enhance the immune response in some people who are immunocompromised. Talk to your doctor if you think you may qualify for a third COVID vaccine dose.

I heard that certain blood pressure medicines might worsen symptoms of COVID-19. Should I stop taking my medication now just in case I do get infected? Should I stop if I develop symptoms of COVID-19?

You are referring to angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), two types of medications used primarily to treat high blood pressure (hypertension) and heart disease. Doctors also prescribe these medicines for people who have protein in their urine, a common problem in people with diabetes.

Here's how this concern got started. Researchers doing animal studies on a different coronavirus (the SARS coronavirus from the early 2000s) found that certain sites on lung cells called ACE-2 receptors appeared to help the SARS virus enter the lungs and cause pneumonia. ACE inhibitor and ARB drugs raised ACE-2 receptor levels in the animals.

But observational studies in humans have found no increased risk of COVID diagnosis, hospitalization, or death in people taking ACE inhibitors or ARBs. A randomized clinical trial published in JAMA in January 2021 further bolstered the evidence for continuing these medications if you get COVID-19. The researchers enrolled adults hospitalized with mild or moderate COVID-19, all of whom were already taking an ACE inhibitor or ARB before hospitalization. About half of the participants were assigned to continue their medication and the others were assigned to discontinue it. The researchers found that people who discontinued their medications did not fare significantly better or worse than those who had continued their medications in terms of likelihood of dying, progression of COVID-19, or time to being released from the hospital.

Another consideration: abruptly stopping your ACE inhibitor or ARB could cause your blood pressure to spike or worsen any underlying heart condition, putting you at greater risk of complications from the infection.

The bottom line: at this time, the American Heart Association (AHA), the American College of Cardiology (ACC), and the Heart Failure Society of America (HFSA) strongly recommend continuing to take ACE inhibitor or ARB medications, even if you get sick with COVID-19.

Blog posts

Podcasts

COVID-19 and underlying conditions: Why symptoms may be more severe for people with chronic disease (recorded 5/6/20)

People who have diabetes, a heart condition, cancer, kidney disease or other underlying condition are impacted more severely if they contract the coronavirus. Harvard Medical School endocrinologist Dr. Enrique Caballero explains why. Dr. Caballero is on the staff of Brigham and Women's Hospital in Boston, Massachusetts, and is the director of diabetes education in the post-graduate medical education department at Harvard Medical School.

Entendiendo como afecta la infección por COVID-19 a personas con enfermedades crónicas subyacentes (recorded 5/6/20)

Las personas que tienen diabetes, una afección del corazón o de los riñones u otra enfermedad crónica subyacente se ven afectadas más severamente si contraen el coronavirus. El Dr. Enrique Caballero, endocrinólogo de la Escuela de Medicina de Harvard explica la forma en que estas enfermedades favorecen infecciones severas por COVID-19 y como el coronavirus puede empeorar estas condiciones crónicas.  El Dr. Caballero forma parte del personal del Hospital Brigham and Women's y es el director de educación en diabetes en el departamento de educación médica de posgrado de la Facultad de Medicina de Harvard en Boston, Massachusetts. 

COVID-19 and the vulnerable: How we can help the sick and the elderly? (recorded 3/17/20)

There's a lot we don't know about the novel coronavirus that's shutting down the world. But we do know this: The sick, the elderly, the immune-compromised are particularly at risk. If you or a loved one fall into this category, there are some things you can do to help keep COVID-19 at bay. As Harvard's Dr. Rob Shmerling points out, it starts with situational awareness.

Visit our Coronavirus Resource Center for more information on coronavirus and COVID-19.

Image: shapecharge/Getty Images

Disclaimer:

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

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