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If you are at higher risk

September 20, 2021

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

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?

In August 2021, the FDA authorized a third dose of an mRNA vaccine (Pfizer/BioNTech or Moderna) for certain people who are 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.

The FDA authorized a third dose for people who are moderately to severely 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.

The FDA and CDC further recommend that 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.

Do I need a COVID vaccine booster shot?

In September 2021, the FDA’s vaccine advisory committee (VRBPAC) recommended authorization of a booster dose of the COVID-19 vaccine for certain Pfizer/BioNTech vaccine recipients. Specifically, authorization of a booster was recommended for people ages 65 years older or who are at risk for severe COVID disease. Eligible people need to wait at least six months after completion of the initial two-dose mRNA vaccine series before they get the third shot. VRBPAC voted to recommend against authorizing a vaccine booster for the general population.

The FDA will now vote on whether to accept VRBPAC’s recommendations. The CDC’s advisory committee on immunization practices (ACIP) will then meet to discuss whether the CDC should recommend the booster dose that the FDA is expected to authorize.

The VRBPAC panel voted unanimously to recommend authorization of a booster dose for people over 65 and those at high risk for severe COVID disease. However, they did not define who would qualify as high risk. A recent CDC report found some decrease in vaccine protection against COVID-related hospitalization in older adults.

Most advisory committee members voted against authorizing a booster dose for the general population. The evidence to date suggests that while vaccine protection against infection may be waning, most people are still well protected against hospitalization and death. However, another recent CDC report did find that protection against hospitalization from the Pfizer vaccine dropped from 91% to 77% at four months after vaccination. A similar drop was not seen for the Moderna vaccine. Still, in a recent analysis of vaccine effectiveness studies published in The Lancet, an international group of scientists wrote that there wasn’t enough evidence to support booster doses for the general population.

The vaccine advisory committee also raised concerns over the shortage of safety data, particularly in male teens and young adults, who have been found to have a higher-than-normal risk of heart inflammation following vaccination with the mRNA COVID-19 vaccines.

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?

A large study from the CDC has found that pregnant women are at increased risk of severe COVID-19 illness compared to women who are not pregnant.

The study looked at 409,462 women, ages 15 to 44, who had symptomatic COVID-19. Of these women, 23,434 were pregnant. Even after taking age, race, ethnicity, and underlying health conditions into consideration, pregnant women were significantly more likely to need intensive care, to require a ventilator, and to require a heart-lung bypass machine, compared to women who were not pregnant. They were also 70% more likely to die.

It's important to note that the overall risk of these complications was low. For example, 1.5 symptomatic pregnant women out of 1,000 died, compared to 1.2 symptomatic women out of 1,000 who were not pregnant.

In addition, COVID-19 increases risk for premature birth, particularly for those with severe illness, and possibly also for other undesirable pregnancy outcomes.

The CDC also released a smaller study, which found that women who were infected with the COVID-19 virus during pregnancy were more likely to deliver preterm (earlier than 37 weeks).

If you are pregnant, be vigilant about taking precautions. Wear a mask, physically distance from others, and avoid social gatherings. Do your best to follow the CDC's recommendations to protect yourself if someone in your household becomes infected. And talk to your doctor about the COVID-19 vaccine. In August 2021, the CDC gave its clearest recommendation to date 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. 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.

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?

In August 2021, the CDC gave its clearest recommendation to date 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. The World Health Organization (WHO) recommends use of a COVID-19 vaccine in pregnant women when the benefit to an individual outweighs the potential vaccine risks. Experts, including the WHO, believe it is most likely safe to get a COVID-19 vaccine if you're breastfeeding. 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.

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, particularly for those with severe illness, and possibly also for other undesirable pregnancy outcomes. Transmission of the virus from mother to baby during pregnancy is possible, but it appears to be a rare event.

The CDC’s stronger recommendation followed new safety data, which was also released in August 2021. The study enrolled 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. The trial looked at 3,958 women who received an mRNA COVID-19 vaccine between mid-December 2020 and late February 2021. Most of the women included in this analysis got the vaccine during their second or third trimester. Of these women, 827 had completed their pregnancy by the end of the study period. There were 712 live births, and the number of miscarriages and other adverse outcomes, including preterm birth and low birth weight, were similar to pregnancy outcomes reported in studies before the COVID-19 pandemic.

Another small study, which 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 are unlikely to reach or cross the placenta.

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.

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