Middle East Respiratory Syndrome

Middle East Respiratory Syndrome is viral respiratory illness that is caused by a newly recognized Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Middle East Respiratory Syndrome was first reported in Saudi Arabia in 2012 and has since spread to several other countries, including the United States ¹. Most people infected with Middle East Respiratory Syndrome Coronavirus developed severe respiratory illness, including fever, cough, and shortness of breath. About 3 or 4 out of every 10 patients reported with Middle East Respiratory Syndrome have died.

So far, all cases of Middle East Respiratory Syndrome have been linked through travel to or residence in, countries in and near the Arabian Peninsula. The largest known outbreak of Middle East Respiratory Syndrome outside the Arabian Peninsula occurred in the Republic of Korea in 2015. The outbreak was associated with a traveler returning from the Arabian Peninsula. Countries considered in and near the Arabian Peninsula include Bahrain; Iraq; Iran; Israel, the West Bank, and Gaza; Jordan; Kuwait; Lebanon; Oman; Qatar; Saudi Arabia; Syria; the United Arab Emirates (UAE); and Yemen.

Middle East Respiratory Syndrome transmission

Middle East Respiratory Syndrome coronavirus (MERS-CoV), like other coronaviruses, likely spreads from an infected person’s respiratory secretions, such as through coughing. However, scientists don’t fully understand the precise ways the Middle East Respiratory Syndrome coronavirus (MERS-CoV) spreads.

Middle East Respiratory Syndrome coronavirus has spread from ill people to others through close contact, such as caring for or living with an infected person. Infected people have spread Middle East Respiratory Syndrome coronavirus to others in healthcare settings, such as hospitals. Researchers studying Middle East Respiratory Syndrome have not seen any ongoing spreading of Middle East Respiratory Syndrome coronavirus in the community.

All reported cases have been linked to countries in and near the Arabian Peninsula. Most infected people either lived in the Arabian Peninsula or recently traveled from the Arabian Peninsula before they became ill. A few people have gotten Middle East Respiratory Syndrome after having close contact with an infected person who had recently traveled from the Arabian Peninsula. The largest known outbreak of Middle East Respiratory Syndrome outside the Arabian Peninsula occurred in the Republic of Korea in 2015 and was associated with a traveler returning from the Arabian Peninsula.

Public health agencies continue to investigate clusters of cases in several countries to better understand how Middle East Respiratory Syndrome coronavirus spreads from person to person.

People who may be at increased risk for Middle East Respiratory Syndrome

Recent travelers from the Arabian Peninsula

If you develop a fever and symptoms of respiratory illness, such as cough or shortness of breath, within 14 days after traveling from countries in or near the Arabian Peninsula, you should call ahead to a healthcare provider and mention your recent travel. However, fever may not be present in some patients, such as those who are very young, elderly, immunosuppressed, or taking certain medications. Clinical judgement should be used to guide testing of patients in such situations.

Close contacts of an ill traveler from the Arabian Peninsula

If you have had close contact with someone within 14 days after they traveled from a country in or near the Arabian Peninsula, and the traveler has/had fever and symptoms of respiratory illness, such as cough or shortness of breath, you should monitor your health for 14 days, starting from the day you were last exposed to the ill person.

If you develop fever and symptoms of respiratory illness, such as cough or shortness of breath, you should call ahead to a healthcare provider and mention your recent contact with the traveler.

Close contacts of a confirmed case of Middle East Respiratory Syndrome

If you have had close contact with someone who has a confirmed Middle East Respiratory Syndrome coronavirus infection, you should contact a healthcare provider for an evaluation. Your healthcare provider may request laboratory testing and outline additional recommendations, depending on the findings of your evaluation and whether you have symptoms. You most likely will be asked to monitor your health for 14 days, starting from the day you were last exposed to the ill person. Watch for these symptoms:

• Fever. Take your temperature twice a day.
• Coughing
• Shortness of breath
• Other early symptoms to watch for are chills, body aches, sore throat, headache, diarrhea, nausea/vomiting, and runny nose.

If you develop symptoms, call ahead to your healthcare provider as soon as possible and tell them about your possible exposure to Middle East Respiratory Syndrome coronavirus so the office can take steps to keep other people from getting infected. Ask your healthcare provider to call the local or state health department.

People with exposure to camels

Direct contact with camels is a risk factor for human infection with Middle East Respiratory Syndrome coronavirus.

The World Health Organization has posted a general precaution for anyone visiting farms, markets, barns, or other places where animals are present. Travelers should practice general hygiene measures, including regular handwashing before and after touching animals, and avoiding contact with sick animals. Travelers should also avoid consumption of raw or undercooked animal products.

The World Health Organization considers certain groups to be at high risk for severe Middle East Respiratory Syndrome. These groups include people with diabetes, kidney failure, or chronic lung disease, and people who have weakened immune systems. The World Health Organization recommends that these groups take additional precautions:

• Avoid contact with camels
• Do not drink raw camel milk or raw camel urine
• Do not eat undercooked meat, particularly camel meat

Healthcare personnel not using recommended infection-control precautions

Healthcare personnel should adhere to recommended infection control measures, including standard, contact, and airborne precautions, while managing symptomatic close contacts, patients under investigation, and patients who have probable or confirmed Middle East Respiratory Syndrome coronavirus infections. They should also use recommended infection control precautions when collecting specimens.

Healthcare personnel who had close contact with a confirmed case of Middle East Respiratory Syndrome while the case was ill, if not using recommended infection control precautions (e.g., appropriate use of personal protective equipment), are at increased risk of developing Middle East Respiratory Syndrome coronavirus infection. These individuals should be evaluated and monitored by a healthcare professional with a higher index of suspicion.

Middle East Respiratory Syndrome prevention

There is currently no vaccine to protect people against Middle East Respiratory Syndrome. But scientists are working to develop one.

You can help reduce your risk of getting respiratory illnesses:

• Wash your hands often with soap and water for at least 20 seconds, and help young children do the same. If soap and water are not available, use an alcohol-based hand sanitizer.
• Cover your nose and mouth with a tissue when you cough or sneeze, then throw the tissue in the trash.
• Avoid touching your eyes, nose, and mouth with unwashed hands.
• Avoid personal contact, such as kissing, or sharing cups or eating utensils, with sick people.
• Clean and disinfect frequently touched surfaces and objects, such as doorknobs.

Preventing Middle East Respiratory Syndrome coronavirus from spreading to others in homes and communities

The following interim guidance may help prevent Middle East Respiratory Syndrome coronavirus from spreading among people in homes and in communities. The interim guidance is based on what we currently know about other viral respiratory infections and Middle East Respiratory Syndrome coronavirus.

This interim guidance is for:

• people confirmed to have Middle East Respiratory Syndrome coronavirus infection who can receive care at home and do not need to be hospitalized for medical reasons
• people being evaluated by a healthcare provider for Middle East Respiratory Syndrome coronavirus infection
• caregivers and household members of a person confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection
• other people who have had close contact2 with a person confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection

Prevention steps for people confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection

If you are confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection you should follow the prevention steps below until a healthcare provider or local or state health department says you can return to your normal activities.

• Stay home: You should restrict activities outside your home, except for getting medical care. Do not go to work, school, or public areas, and do not use public transportation or taxis.
• Separate yourself from other people in your home: As much as possible, you should stay in a different room from other people in your home. Also, you should use a separate bathroom, if available.
• Call ahead before visiting your doctor: Before your medical appointment, call the healthcare provider and tell him or her that you have, or are being evaluated for, Middle East Respiratory Syndrome coronavirus infection. This will help the healthcare provider’s office take steps to keep other people from getting infected.
• Wear a facemask: You should wear a facemask when you are in the same room with other people and when you visit a healthcare provider. If you cannot wear a facemask, the people who live with you should wear one while they are in the same room with you.
• Cover your coughs and sneezes: Cover your mouth and nose with a tissue when you cough or sneeze, or you can cough or sneeze into your sleeve. Throw used tissues in a lined trash can, and immediately wash your hands with soap and water for at least 20 seconds.
• Wash your hands: Wash your hands often and thoroughly with soap and water for at least 20 seconds. You can use an alcohol-based hand sanitizer if soap and water are not available and if your hands are not visibly dirty. Avoid touching your eyes, nose, and mouth with unwashed hands.
• Avoid sharing household items: You should not share dishes, drinking glasses, cups, eating utensils, towels, bedding, or other items with other people in your home. After using these items, you should wash them thoroughly with soap and water.
• Monitor your symptoms: Seek prompt medical attention if your illness is worsening (e.g., difficulty breathing). Before going to your medical appointment, call the healthcare provider and tell him or her that you have, or are being evaluated for, Middle East Respiratory Syndrome coronavirus infection. This will help the healthcare provider’s office take steps to keep other people from getting infected. Ask your healthcare provider to call the local or state health department.

Prevention steps for caregivers and household members

If you live with, or provide care at home for, a person confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection, you should:

• Make sure that you understand and can help the person follow the healthcare provider’s instructions for medication and care. You should help the person with basic needs in the home and provide support for getting groceries, prescriptions, and other personal needs.
• Have only people in the home who are essential for providing care for the person.
  • Other household members should stay in another home or place of residence. If this is not possible, they should stay in another room, or be separated from the person as much as possible. Use a separate bathroom, if available.
  • Restrict visitors who do not have an essential need to be in the home.
  • Keep elderly people and those who have compromised immune systems or certain health conditions away from the person. This includes people with chronic heart, lung or kidney conditions, and diabetes.
• Make sure that shared spaces in the home have good air flow, such as by an air conditioner or an opened window, weather permitting.
• Wash your hands often and thoroughly with soap and water for at least 20 seconds. You can use an alcohol-based hand sanitizer if soap and water are not available and if your hands are not visibly dirty. Avoid touching your eyes, nose, and mouth with unwashed hands.
• Wear a disposable facemask, gown, and gloves when you touch or have contact with the person’s blood, body fluids and/or secretions, such as sweat, saliva, sputum, nasal mucus, vomit, urine, or diarrhea.
  • Throw out disposable facemasks, gowns, and gloves after using them. Do not reuse.
  • Wash your hands immediately after removing your facemask, gown, and gloves.
• Avoid sharing household items. You should not share dishes, drinking glasses, cups, eating utensils, towels, bedding, or other items with a person who is confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection. After the person uses these items, you should wash them thoroughly.
• Clean all “high-touch” surfaces, such as counters, tabletops, doorknobs, bathroom fixtures, toilets, phones, keyboards, tablets, and bedside tables, every day. Also, clean any surfaces that may have blood, body fluids and/or secretions or excretions on them.
  • Read label of cleaning products and follow recommendations provided on product labels. Labels contain instructions for safe and effective use of the cleaning product including precautions you should take when applying the product, such as wearing gloves or aprons and making sure you have good ventilation during use of the product.
  • Use a diluted bleach solution or a household disinfectant with a label that says “EPA-approved.” To make a bleach solution at home, add 1 tablespoon of bleach to 1 quart (4 cups) of water. For a larger supply, add ¼ cup of bleach to 1 gallon (16 cups) of water.
• Wash laundry thoroughly.
  • Immediately remove and wash clothes or bedding that have blood, body fluids and/or secretions or excretions on them.
  • Wear disposable gloves while handling soiled items. Wash your hands immediately after removing your gloves.
  • Read and follow directions on labels of laundry or clothing items and detergent. In general, wash and dry with the warmest temperatures recommended on the clothing label.
• Place all used gloves, gowns, facemasks, and other contaminated items in a lined container before disposing them with other household waste. Wash your hands immediately after handling these items.
• Monitor the person’s symptoms. If they are getting sicker, call his or her medical provider and tell him or her that the person has, or is being evaluated for, Middle East Respiratory Syndrome coronavirus infection. This will help the healthcare provider’s office take steps to keep other people from getting infected. Ask the healthcare provider to call the local or state health department.
• Caregivers and household members who do not follow precautions when in close contact2 with a person who is confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection, are considered “close contacts” and should monitor their health. Follow the prevention steps for close contacts below.

Prevention steps for close contacts

If you have had close contact with someone who is confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection, you should:

• Monitor your health starting from the day you were first exposed to the person and continue for 14 days after you were last exposed to the person. Watch for these signs and symptoms:
  • Fever. Take your temperature twice a day.
  • Coughing.
  • Shortness of breath.
  • Other early symptoms to watch for are chills, body aches, sore throat, headache, diarrhea, nausea/vomiting, and runny nose.
• If you develop symptoms, follow the prevention steps described above, and call your healthcare provider as soon as possible. Before going to your medical appointment, call the healthcare provider and tell him or her about your possible exposure to Middle East Respiratory Syndrome coronavirus. This will help the healthcare provider’s office take steps to keep other people from getting infected. Ask your healthcare provider to call the local or state health department.
• If you do not have any symptoms, you can continue with your daily activities, such as going to work, school, or other public areas.

You are not considered to be at risk for Middle East Respiratory Syndrome coronavirus infection if you have not had close contact with someone who is confirmed to have, or being evaluated for, Middle East Respiratory Syndrome coronavirus infection. The Centers for Disease Control and Prevention (CDC) advises that people follow prevention steps to help reduce their risk of getting infected with respiratory viruses, like Middle East Respiratory Syndrome coronavirus.

Middle East Respiratory Syndrome symptoms

A wide clinical spectrum of Middle East Respiratory Syndrome coronavirus infection has been reported ranging from asymptomatic infection to acute upper respiratory illness, and rapidly progressive pneumonitis, respiratory failure, septic shock and multi-organ failure resulting in death ². Most Middle East Respiratory Syndrome coronavirus cases have been reported in adults (median age approximately 50 years, male predominance), although children and adults of all ages have been infected (range 0 to 109 years). Most hospitalized Middle East Respiratory Syndrome coronavirus patients have had chronic co-morbidities. Among confirmed Middle East Respiratory Syndrome coronavirus cases reported to date, the case fatality proportion is approximately 35%.

Limited clinical data for Middle East Respiratory Syndrome coronavirus patients are available; most published clinical information to date is from critically ill patients. At hospital admission, common signs and symptoms include fever, chills/rigors, headache, non-productive cough, dyspnea, and myalgia. Other symptoms can include sore throat, coryza, nausea and vomiting, dizziness, sputum production, diarrhea, and abdominal pain. Atypical presentations including mild respiratory illness without fever and diarrheal illness preceding development of pneumonia have been reported. Patients who progress to requiring admission to an intensive care unit (ICU) often have a history of a febrile upper respiratory tract illness with rapid progression to pneumonia within a week of illness onset.

Most people confirmed to have Middle East Respiratory Syndrome coronavirus infection have had severe respiratory illness with symptoms of:

• fever
• cough
• shortness of breath

Some people also had diarrhea and nausea and vomiting. For many people with Middle East Respiratory Syndrome, more severe complications followed, such as pneumonia and kidney failure. About 3 or 4 out of every 10 people reported with Middle East Respiratory Syndrome have died. Most of the people who died had a pre-existing medical condition that weakened their immune system, or an underlying medical condition that hadn’t yet been discovered. Medical conditions sometimes weaken people’s immune systems and make them more likely to get sick or have severe illness.

Pre-existing conditions among people who got Middle East Respiratory Syndrome have included

• diabetes
• cancer
• chronic lung disease
• chronic heart disease
• chronic kidney disease

Some infected people had mild symptoms (such as cold-like symptoms) or no symptoms at all.

The symptoms of Middle East Respiratory Syndrome start to appear about 5 or 6 days after a person is exposed, but can range from 2 to 14 days.

Clinical course

The median incubation period for secondary cases associated with limited human-to-human transmission is approximately 5 days (range 2-14 days). In Middle East Respiratory Syndrome coronavirus patients, the median time from illness onset to hospitalization is approximately 4 days. In critically ill patients, the median time from onset to intensive care unit (ICU) admission is approximately 5 days, and median time from onset to death is approximately 12 days. In one series of 12 ICU patients, the median duration of mechanical ventilation was 16 days, and median ICU length of stay was 30 days, with 58% mortality at 90 days. Radiographic findings may include unilateral or bilateral patchy densities or opacities, interstitial infiltrates, consolidation, and pleural effusions. Rapid progression to acute respiratory failure, acute respiratory distress syndrome (ARDS), refractory hypoxemia, and extrapulmonary complications (acute kidney injury requiring renal replacement therapy, hypotension requiring vasopressors, hepatic inflammation, septic shock) has been reported.

Middle East Respiratory Syndrome diagnosis

The Centers for Disease Control and Prevention (CDC) recommends collecting multiple specimens from different sites and times in suspected cases of Middle East respiratory syndrome, including nasopharyngeal and oropharyngeal swabs, sputum, serum, and stool/rectal swabs after symptom onset.

Collection of all three specimen types (not just one or two of the three), lower respiratory, upper respiratory and serum specimens for testing using the CDC Middle East Respiratory Syndrome real-time reverse-transcription polymerase chain reaction (rRT-PCR) assay is recommended. Lower respiratory specimens are preferred, but collecting nasopharyngeal and oropharyngeal specimens, and serum, are strongly recommended depending upon the length of time between symptom onset and specimen collection. Respiratory specimens should be collected as soon as possible after symptoms begin – ideally within 7 days. However, if more than a week has passed since symptom onset and the patient is still symptomatic, respiratory samples should still be collected, especially lower respiratory specimens since respiratory viruses can still be detected by real-time reverse-transcription polymerase chain reaction (rRT-PCR). For example, evidence shows that lower respiratory tract specimens such as bronchoalveolar lavage (BAL), sputum, and tracheal aspirates contain the highest viral loads, and these are recommended. Some cases, including the second US case, have been confirmed only in sputum after negative or equivocal results on polymerase chain reaction (PCR) for Middle East Respiratory Syndrome coronavirus in nasopharyngeal and oropharyngeal specimens.

The local health department should be notified immediately if a patient is suspected of having Middle East Respiratory Syndrome coronavirus infection. Proper personal protective precautions should be used by personnel collecting specimens (ie, gloves, eye protection, gowns, and respiratory protection with N-95 masks).

The CDC conducts several different laboratory tests to detect Middle East Respiratory Syndrome coronavirus infection.

In general, these lab tests fall into two categories:

1. Molecular tests, which look for evidence of active infection; and
2. Serology tests, which look for previous infection by detecting antibodies to Middle East Respiratory Syndrome coronavirus. Serology tests are for surveillance or investigational purposes and not for diagnostic purposes.

Molecular tests

Molecular tests are used to diagnose active infection (presence of Middle East Respiratory Syndrome coronavirus) in people who are thought to be infected with Middle East Respiratory Syndrome coronavirus based on their clinical symptoms and having links to places where Middle East Respiratory Syndrome has been reported.

• Real-time reverse-transcription polymerase chain reaction (rRT-PCR) assays are molecular tests that can be used to detect viral RNA in clinical samples. CDC’s current case definition for laboratory confirmation of Middle East Respiratory Syndrome coronavirus infection requires either a positive rRT-PCR result for at least two specific genomic targets, or a single positive target with sequencing of a second target.
• Most state laboratories in the United States are approved to test for Middle East Respiratory Syndrome coronavirus by using an rRT-PCR assay developed by CDC. This test is done under authority of an Emergency Use Authorization because there are no FDA-cleared/approved tests available for this purpose in the United States.
• The success of rRT-PCR testing depends on several factors, including the experience and expertise of laboratory personnel, laboratory environment (e.g., avoidance of contamination), and the type and condition of specimens being tested. For this rRT-PCR assay, CDC recommends collecting multiple specimens, including lower (bronchalveolar lavage, sputum and tracheal aspirates) and upper (e.g., nasopharyngeal and oropharyngeal swabs) respiratory samples, serum, and stool specimens.
• CDC considers a patient under investigation to be negative for active Middle East Respiratory Syndrome coronavirus infection following one negative rRT-PCR test on the recommended specimens. Since a single negative result does not completely rule out Middle East Respiratory Syndrome coronavirus infection, in some circumstances additional specimens may be tested.
• CDC considers a known Middle East Respiratory Syndrome patient to be negative for active Middle East Respiratory Syndrome coronavirus infection following two consecutive negative rRT-PCR tests on all specimens.

Serology tests

Serology testing is used to detect previous infection (antibodies to Middle East Respiratory Syndrome coronavirus) in people who may have been exposed to the virus. Antibodies are proteins produced by the body’s immune system to attack and kill viruses, bacteria, and other microbes during infection. The presence of antibodies to Middle East Respiratory Syndrome coronavirus indicates that a person had been previously infected with the virus and developed an immune response.

• Evidence to date suggests there may be a broader range of Middle East Respiratory Syndrome disease than was initially thought. For example, public health investigators have identified individuals who are PCR-positive but have no Middle East Respiratory Syndrome symptoms; we do not know if Middle East Respiratory Syndrome coronavirus can be spread by these people. For this reason, public health scientists are working to learn more about how the virus is transmitted. One way to do this is through voluntary testing of blood samples from people who had close contact with people known to have Middle East Respiratory Syndrome.
• CDC has a two-phase approach for serology testing, using two screening tests and one confirmatory test to detect antibodies to Middle East Respiratory Syndrome coronavirus.
  • Enzyme-Linked Immunosorbent Assay (ELISA), is a screening test used to detect the presence and concentration of specific antibodies that bind to a viral protein. CDC tests by ELISAS for antibodies against two different Middle East Respiratory Syndrome coronavirus proteins, the nucleocapsid (N) and spike (S).
    • If a clinical sample is determined to be antibody-positive by either ELISA, CDC then uses the microneutralization test to confirm the positive result.
  • The microneutralization assay is a highly specific confirmatory test used to measure neutralizing antibodies, or antibodies that can neutralize virus. This method is considered a gold standard for detection of specific antibodies in serum samples. However, compared with the ELISA, the microneutralization assay is labor-intensive and time-consuming, requiring at least 5 days before results are available.
    • If a clinical sample is positive by either ELISA, and positive by microneutralization, the specimen is determined to be confirmed positive.
    • If a clinical sample is positive by both ELISAs, and negative by microneutralization, the sample is determined to be indeterminate.
    • If a clinical sample is positive by only one ELISA, and negative by microneutralization, the sample is determined to be negative.
    • If a clinical sample is negative by both ELISAS, the sample is determined negative.
  • In the end, a final determination of a confirmed positive serology result requires a positive ELISA test and confirmation by microneutralization assay.
• Middle East Respiratory Syndrome coronavirus serology tests are for surveillance or investigational purposes and not for diagnostic purposes—they are tools developed in response to the Middle East Respiratory Syndrome coronavirus outbreak.
• Information is limited about Middle East Respiratory Syndrome coronavirus and how the virus is spread. As public health scientists learn more about Middle East Respiratory Syndrome coronavirus, the approach to conducting these types of laboratory tests might change.

Middle East Respiratory Syndrome treatment

There is no specific antiviral treatment recommended for Middle East Respiratory Syndrome coronavirus infection. Individuals with Middle East Respiratory Syndrome often receive medical care to help relieve symptoms. For severe cases, current treatment includes care to support vital organ functions.

A recent study demonstrated activity of mycophenolic acid against the novel Middle East Respiratory Syndrome coronavirus; its potent in vitro activity may allow it to be used as monotherapy ³.

Ribavirin and interferon alfa have synergistic in vitro effects against the virus, but their role (if any) in the treatment of Middle East Respiratory Syndrome remains unknown.

A small observational study of 5 patients with Middle East Respiratory Syndrome coronavirus infection receiving ribavirin in combination with interferon alfa 2b in Saudi Arabia failed to show any benefit. These patients were all critically ill and on mechanical ventilation, and the median time from admission to therapy was 19 days, perhaps too late to demonstrate any benefit.

Similarly, Morra et al ³, in a systematic review and meta-analysis, found that ribavirin plus interferon did not improve survival rates over supportive treatment alone.

For more information on Middle East Respiratory Syndrome coronavirus infection, see the World Health Organization guidance for clinical management of severe acute respiratory syndrome when Middle East Respiratory Syndrome coronavirus infection is suspected https://apps.who.int/iris/bitstream/handle/10665/178529/WHO_MERS_Clinical_15.1_eng.pdf?sequence=1&isAllowed=y.

References

1. https://www.cdc.gov/coronavirus/mers/
2. Middle East Respiratory Syndrome (MERS) Clinical Features. https://www.cdc.gov/coronavirus/mers/clinical-features.html
3. Morra ME, Van Thanh L, Kamel MG, Ghazy AA, Altibi AMA, Dat LM, et al. Clinical outcomes of current medical approaches for Middle East respiratory syndrome: A systematic review and meta-analysis. Rev Med Virol. 2018 May. 28 (3):e1977.