Covid-19 is a viral disease with specific stages of the covid-19 infection. Experts at Meri Sehat encourage Covid-19 vaccine to avoid coronavirus symptoms.

COVID-19

Overview

Coronavirus causes a range of illnesses, which also include COVID-19. The respiratory tract is typically affected; however, the effect can be way beyond the respiratory tract. Coronavirus was first identified in 1937, which caused bronchitis in birds and had the potential to harm stocks of poultry. Moreover, evidence of human coronavirus was found in the nose of people who had symptoms of the common cold. Coronavirus infects humans and usually occurs during winter and early spring. However, considering the current pandemic of 2019, it can occur in any season.

COVID-19 is an illness caused by a novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was formerly known as 2019-nCoV. The first outbreak was seen in Wuhan, China.

&nbsp;

The initial report was given on 31st December 2019 and on 30th January 2020, the WHO declared it a global health emergency.&nbsp; On 11th March 2020, WHO declared COVID-19 a global pandemic, which was its first designation since the influenza pandemic in 2009. World Health Organization termed the illness caused by SARS-CoV-2 as COVID-19. The term was given to prevent confusion with other populations, animals, or geography.&nbsp;

The CDC estimated that the virus entered the US in late January or early February 2020. A low-level community spread had been established before it was noticed. The US has experienced widespread infections since then, with over 82.3 million cases reported and 1 million deaths, according to the report of May 15th, 2020<a href="#accordion">[1]</a>. 
Moreover, according to CDC, 75% of the people who died of COVID-19 in the US as of December 29th, 2021, were aged sixty-five and older<a href="#accordion">[2]</a>. 
The CDC issued a recommendation on April 3rd, 2020, that people should start wearing face masks in public gatherings, despite the absence of symptoms, because social distancing was difficult to manage during COVID-19.

&nbsp;

<h5>What Is Coronavirus?</h5>

Coronavirus is a family of viruses that causes respiratory illnesses in humans. The name is based on the crown-like spikes on the surface of the virus. MERS (middle respiratory syndrome) and <a href="https://merisehat.pk/disease/severe-acute-respiratory-syndrome-sars">SARS</a> (severe acute respiratory syndrome) are examples of illnesses caused by a coronavirus in humans.

&nbsp;

<h5>Where Does The Virus Come From?</h5>

Coronavirus is found in bats, cats, and camels. The viruses live in the animals but don&rsquo;t infect them. Sometimes, they spread to different species of animals. Moreover, the viruses can mutate when they transfer to other species. The virus can eventually spread from those animal species and infect humans. The first people to have contracted SARS-CoV-2 got it from a food market that sold meat, fish, and live animals.

&nbsp;

<h5>How Is COVID-19 Contracted?</h5>

SARS-CoV-19 enters the body via the mouth, nose, or eyelids. It can either be through airborne droplets or from your hands to your face. It travels to the back of your nasal passages and the mucous membrane behind the throat. After attaching to the cells there, it starts multiplying and moving to the lung tissues. The virus spreads to other body tissues from there. 
&nbsp;

There are seven types of coronaviruses, and all can cause upper respiratory tract infections. The symptoms mimic those of the flu or common cold. 
&nbsp;

<ul>
	<li>Sore throat</li>
	<li><a href="https://merisehat.pk/disease/whopping-cough">Cough</a></li>
	<li>Nasal congestion</li>
	<li>Headaches</li>
	<li>Fever</li>
</ul>

According to CDC, the complications of coronavirus in the lower respiratory tract are occasional and include pneumonia<a href="#accordion">[3]</a>. The complications are common in infants, older adults, and people who are immunocompromised or have other illnesses.

The seven coronaviruses are categorized into two:

<h4>1. Human Coronaviruses&nbsp;</h4>

<ul>
	<li>229E</li>
	<li>NL63</li>
	<li>OC43</li>
	<li>HKU1</li>
</ul>

The common coronavirus causes mild to severe symptoms and people across the world have the probability of developing these viral infections at least once in their life<a href="#accordion">[4]</a>. However, in most cases, the infection recovers on its own. 
&nbsp;

<h4>2. Other Human Coronaviruses</h4>

Additional three coronaviruses originated, evolved, and were transmitted to humans. They pose a tremendously serious risk to the health of humans. 
&nbsp;

<ul>
	<li><a href="https://merisehat.pk/disease/severe-acute-respiratory-syndrome-sars">SARS</a>-CoV</li>
</ul>

SARS-CoV causes the disease SARS (severe acute respiratory syndrome), According to the WHO, the first case in humans appeared in November 2002 in southern China. The virus may have originated from bats and transmitted to other animals, eventually infecting humans.

During the epidemic in 2002-2003, more than 8,000 people contracted SARS in twenty-six countries across the world. A total number of 774 deaths had been reported<a href="#accordion">[5]</a>. It was contained in the middle of 2003 with the help of infection control practices and quarantine. However, a handful of cases have occurred since then.

Currently, no cases of SARS have been reported across the world, but re-emergence can be a significant threat. 
&nbsp;

<ul>
	<li>MERS-CoV</li>
</ul>

Middle Eastern Respiratory Syndrome MERS-CoV emerged in 2012 in Saudi Arabia. However, the initial cases were traced back to Jordan.

The virus was contracted by humans through camels that had the infection, and transmitted between people through close contact with those infected.

Moreover, 2,400 cases of MERS-CoV have been reported since, and the majority occurred in Saudi Arabia.&nbsp;Furthermore, an outbreak in 2015 led to 36 deaths in 186 cases. Research claims that it originated from a traveler returning from the Middle East<a href="#accordion">[6]</a>. In 2019, more cases were reported and health authorities across the globe are continuing to monitor the cases. 
&nbsp;

<ul>
	<li>SARS-CoV-2</li>
</ul>

SARS-CoV that caused COVID-19 originated in Wuhan, China in late December 2019 when health officials saw an increase in cases of <a href="https://merisehat.pk/disease/pneumonia">pneumonia</a> with no underlying cause.

The cases were linked with the poultry and seafood being sold in the markets, through which the virus most likely evolved. However, the definitive source was unknown in 2019. The virus spread across the globe within just a few months after being transmitted from person-to-person contact.

&nbsp;

Signs And Symptoms

The symptoms of COVID-19 vary from person to person. Some people who have been infected are asymptomatic while in general, people with COVID report the following symptoms: 
&nbsp;

<ul>
	<li>Fever</li>
	<li>Chills</li>
	<li><a href="https://merisehat.pk/disease/cold-flu">Cough</a></li>
	<li>Breathing difficulties and shortness of breath</li>
	<li>Muscle and body aches</li>
	<li><a href="https://merisehat.pk/disease/migraines-73">Headaches</a></li>
	<li>Sore throat</li>
	<li>Ageusia</li>
	<li>Runny nose</li>
	<li>Congestion</li>
	<li>Nausea</li>
	<li>Vomiting</li>
	<li>Diarrhoea&nbsp; 
	&nbsp;</li>
</ul>

Other than the symptoms that have been listed, additional symptoms are also possible. The symptoms appear two to fourteen days after being exposed to the virus. Although children have the same symptoms, they are milder compared to adults. Older adults with severe medical conditions have higher risks of serious complications that are as follows:&nbsp; 
&nbsp;

<ul>
	<li>Breathing difficulties</li>
	<li>Persistent pain or pressure in the chest</li>
	<li>Confusion</li>
	<li>It becomes difficult to wake up</li>
	<li>Bluish face or lips 
	&nbsp;</li>
</ul>

These aren&rsquo;t all the possible symptoms of COVID-19, but you should contact your healthcare provider if you think you have coronavirus or any of the severe symptoms. Moreover, it is a notification priority disease and should be reported immediately.

&nbsp;

Causes

The virus is contagious and spread easily from one person to another. The virus can transmit through fluids and the respiratory system.

 
The transmission happens in the following cases:

<ul>
	<li>Coughing and sneezing without covering the mouth, and when the droplets containing the virus contaminate the air.</li>
	<li>Having physical contact with someone who is infected.</li>
	<li>Touching any surface that has the virus and then touching your eyes or mouth.</li>
</ul>

&nbsp;

Preventive measures can be used to prevent the virus from the transmission:

<ul>
	<li>Wear a face mask in public</li>
	<li>Avoid touching the mouth, nose, and face</li>
	<li>Sneeze or cough into a tissue or on your elbow. Wash your hands right away after sneezing and coughing</li>
	<li>Wash your hands regularly and thoroughly</li>
</ul>

Vaccines can prevent getting the SARS-CoV-2 infection.

&nbsp;

Diagnosis

If patients have a respiratory tract infection or newly onset fever, COVID-19 should be taken into consideration. Especially, if they have no clear cause for the symptoms. Furthermore, suspicion is increased if they have been in contact with someone who has the virus or has been in an area with community transmission of COVID-19 in the last fourteen days. Microbiologic testing is needed for the diagnosis.

It is also recommended that patients who do not require emergency care contact their healthcare provider via telephone/ mobile. Patients presenting to a healthcare facility with suspected COVID-19 should religiously follow infection-control measures. It is also ideal that the patients are examined in a closed room (airborne infection isolation room) and are instructed to wear a mask. Moreover, all other standard airborne and contact precautions should be taken. For example, the treating healthcare worker should wear eye protection, masks, and PPE (Personal Protective Equipment).

Tests for COVID-19 include nasopharyngeal swabs, throat swabs, or samples of saliva, which are then sent for testing in labs. FDA has also approved home testing for the COVID-19 virus. 
&nbsp;

<h5>PCR Test</h5>

Polymerase chain reaction testing is the primary diagnostic method for COVID-19 and is the same test that has been used previously for the diagnosis of SARS in 2002. 
The following samples are collected by healthcare providers: 
&nbsp;

<ul>
	<li>A swab from the nose or back of the throat</li>
	<li>Fluid aspirated from the lower respiratory tract</li>
	<li>Saliva or stool sample 
	&nbsp;</li>
</ul>

It is followed by the extraction of the nucleic acid from the sample of the virus to amplify the genome through a reverse transcription PCR technique. This gives a larger viral sample for comparison. In addition to that, the samples of RT-PCR are often tested in batches, so it does take a day or more to get the results.&nbsp; 
&nbsp;

Two genes are found in the genome and the results are:

<ul>
	<li>If both genes are found, then the results are positive</li>
	<li>If only one gene is found, it is inconclusive&nbsp;</li>
	<li>If neither gene is found, it is negative</li>
</ul>

A CT scan can also be done to get a clearer diagnosis of how the virus spreads. 
&nbsp;

<h5>POC</h5>

FDA has also approved Cephoid <a href="https://merisehat.pk/disease/polycystic-ovary-syndrome-pcos">POC</a> (point-of-care) testing devices, which will be rolling out in high-priority settings. For example, ERs, and hospital units. However, this test is reserved for healthcare staff who are returning to work followed by COVID-19 exposure and those with the virus. 
The newly approved POC allows for the samples to be tested and collected at one location, and it has a quicker turnaround of forty-five minutes. 
&nbsp;

<h4>"COVID infections can lower the oxygen saturation. Check out your oxygen levels with our <a href="https://www.merisehat.pk/page/sehat-scan/" target="_blank">sehat scan</a>!" </h4>

Treatment

It is essential that programs established by FDA should be utilized by clinicians, so they have access to investigational therapies during the virus outbreak. The EA and EUA programs permitted the rapid deployment of potential investigative therapies and therapies for investigation with emerging evidence.&nbsp;

In October 2019, the first antiviral agent to get approval from FDA was Remdesivir for the treatment of COVID-19. The indication of the medication was for the treatment of COVID-19 in children under twelve who weigh a minimum of 40kg and hospitalized adults. The EUA is the same, which is treating kids under twelve who weigh at least 3.5kg. Furthermore, in August 2021, the first vaccine to get full approval was the mRNA-COVID-19 vaccine (Pfizer). 
 
In the United States, EUAs have been issued for vaccines, convalescent plasma, monoclonal-directed antibodies, baricitinib (Janus kinase inhibitor), and tocilizumab. The survival rate of critically hospitalized patients is improved when corticosteroids are used. The greatest benefit is seen in patients who require mechanical ventilation. Moreover, infected patients should also receive supportive care to alleviate the symptoms. In severe cases, vital organs should be supported.&nbsp;

Multiple collaborative efforts have evaluated whether antivirals, monoclonal antibodies, and immunotherapies are effective. Vaccines have also emerged rapidly with guidelines and reviews published by pharmaceutical.

&nbsp;

People who have comorbidities, for example, diabetes or heart diseases are at a higher risk of COVID-19 complications. Moreover, some of the complications are life-threatening and are caused by cytokine release syndrome. The infection triggers the immune system, flooding the bloodstream with cytokines (inflammatory proteins). They can lead to tissue damage, and lung, heart, and kidney damage.

The complications include the following: 
&nbsp;

<ul>
	<li>
	<h5>Acute Respiratory Failure</h5>
	</li>
</ul>

The lungs do not pump enough oxygen in acute respiratory failure and are unable to take out enough carbon dioxide. The two issues can occur simultaneously. Moreover, acute respiratory failure can also lead to death.

&nbsp;

<ul>
	<li>
	<h5>Pneumonia</h5>
	</li>
</ul>

People with COVID-19 can also get pneumonia in both lungs, which is a serious and fatal illness. The air sacs of the lungs become inflamed and make it hard to breathe. Patients with COVID-19 have fluid, cell debris, and pus accumulation in their lungs because of which their bodies do not transfer enough blood to keep their systems working.

&nbsp;

<ul>
	<li>
	<h5>Acute Respiratory Distress Syndrome (ARDS)</h5>
	</li>
</ul>

Acute respiratory distress syndrome is also a complication of COVID-19, in which the lungs become very damaged, and fluid starts leaking into them. This eventually leads to trouble getting oxygen into the bloodstream. Therefore, patients require mechanical help, for example, a ventilator to breathe.

&nbsp;

<ul>
	<li>
	<h5>Acute Liver Injury</h5>
	</li>
</ul>

Patients who are very ill are at risk of liver damage due to the virus. Although, the reason behind it is not clear. Acute liver injury or liver failure is a fatal complication.

 
&nbsp;

<ul>
	<li>
	<h5>Acute Cardiac Injury</h5>
	</li>
</ul>

Hospitalized COVID-19 patients are also prone to developing heart problems, which include high levels of cardiac ailments and arrhythmias. The definitive cause is unknown, but the virus can cause cardiac problems post-recovery as well. However, not enough evidence is present as to why it happens. 
 
&nbsp;

<ul>
	<li>
	<h5>Secondary Infection</h5>
	</li>
</ul>

Secondary infection is possible, but it is not a common complication. People fighting the virus can get infected by bacteria, most commonly streptococcus and staphylococcus. Moreover, it can be serious enough to lead to death. 
 
&nbsp;

<ul>
	<li>
	<h5>Acute Kidney Injury</h5>
	</li>
</ul>

Although it isn&rsquo;t a common complication, if it happens, treatment is started immediately to stop further damage. In some patients, dialysis may be needed to get the kidneys to work again. However, the damage may not always recover and patients may get chronic kidney disease, which requires long-term management.&nbsp;

&nbsp;

<ul>
	<li>
	<h5>Septic Shock</h5>
	</li>
</ul>

This is a life-threatening condition, and the blood pressure drops to a very low level after the infection.

&nbsp;

<ul>
	<li>
	<h5>Disseminated Intravascular Coagulation (DIC) And Blood Clots</h5>
	</li>
</ul>

The body&rsquo;s clotting response does not work in DIC, and abnormal clots start forming, which leads to organ failure or internal bleeding. DIC is common in patients who have died because of COVID-19.

&nbsp;

<ul>
	<li>
	<h5>Multisystem Inflammatory Syndrome In Children</h5>
	</li>
</ul>

Although healthcare workers are still trying to learn about this condition, some children and teens with COVID-19 have been hospitalized because of the multisystem inflammatory syndrome in children. The symptoms are fever, vomiting, diarrhea, belly pain, headache, and confusion.&nbsp;

&nbsp;

<ul>
	<li>
	<h5>Chronic Fatigue</h5>
	</li>
</ul>

People with the virus have also developed a condition like chronic fatigue syndrome, which causes brain fog, pain, trouble thinking, severe fatigue, and dizziness.

&nbsp;

<ul dir="ltr">
	<li>
	<h5 dir="ltr">Rhabdomyolysis</h5>
	</li>
</ul>

This is a very rare condition in which the muscles break down and the tissues die. Myoglobin floods the bloodstream and cells start falling apart. If the kidneys do not flush it out quickly enough, it can lead to death. 
&nbsp;

The symptoms of the virus vary and while some people are asymptomatic, others become extremely sick, requiring hospital intervention, and even a ventilator for assisted breathing<a href="#accordion">[7]</a>.

Older people are at a higher risk of developing COVID-19 symptoms, and the risk is increased in those who have comorbidities<a href="#accordion">[7]</a>. For example, heart disease, lung conditions, diabetes, obesity, and weakened immune systems. It is similar to the symptoms seen in other respiratory illnesses like influenza.&nbsp;

All these factors increase the risk of COVID-19 symptoms. However, people with several health problems are at a greater risk. 
&nbsp;

<ul>
	<li>
	<h5>Old Age</h5>
	</li>
</ul>

People can be affected by COVID-19 at any age, but it affects people in their middle age and older adults more commonly. The risk of developing dangerous symptoms is higher in people above the age of eighty-five. In the United States, 81% percent of deaths due to COVID-19 were among people sixty-five and older<a href="#accordion">[8]</a>. Furthermore, the risks are higher for people with other comorbidities.

If you get COVID-19 and need to visit the ER, take all your medications and prescriptions along with your emergency contacts. People who live in nursing homes are also at high risk because they have various health problems. Moreover, germs can spread easily among people who live close to each other, and specific guidelines should be followed if you are living in a nursing home. Older adults also likely have Alzheimer&rsquo;s, which can make it more difficult to take recommended precautions.

&nbsp;

<ul>
	<li>
	<h5>Lung Conditions And <a href="http://merisehat.pk/disease/asthma">Asthma</a>&nbsp;</h5>
	</li>
</ul>

The virus targets the lungs, so people develop severe symptoms if they already have chronic lung problems, which are:

<ul>
	<li><a href="https://merisehat.pk/disease/copd">COPD (chronic obstructive pulmonary disease)</a></li>
	<li><a href="https://merisehat.pk/disease/lung-cancer-67">Lung cancer</a></li>
	<li>Moderate or severe asthma</li>
	<li>Pulmonary fibrosis</li>
	<li>Pulmonary embolism</li>
	<li><a href="https://merisehat.pk/disease/pulmonary-hypertension">Pulmonary hypertension</a> 
	&nbsp;</li>
</ul>

Some of the prescription medications that people with lung diseases take can weaken their immune systems. It is necessary to stay on maintenance medications to keep the symptoms at bay. Moreover, they may also want to talk to their healthcare provider about an emergency supply of prescription medications, for example, inhalers for asthma.

It is also helpful to avoid anything that triggers asthma and that varies from person to person. Other than asthma, smoking, and vaping can also develop serious symptoms of COVID-19 and weaken your immune system. 
&nbsp;

<ul>
	<li>
	<h5>Heart Disease</h5>
	</li>
</ul>

Heart diseases can make you develop severe COVID-19 symptoms. The diseases include the following:

<ul>
	<li>Congenital Heart Failure</li>
	<li>Cardiomyopathy</li>
	<li><a href="https://merisehat.pk/disease/coronary-artery-disease">Heart failure</a></li>
	<li>CAD (coronary artery disease)</li>
</ul>

Patients should continue taking their medications according to their prescription and if they have high blood pressure, the risk increases. Therefore, taking medications as directed to keep the blood pressure in control is necessary.

&nbsp;

<ul>
	<li>
	<h5>Brain And Nervous System Conditions</h5>
	</li>
</ul>

Conditions of the brain or nervous system can increase your risk of severe symptoms of COVID-19. They include dementia and stroke.

&nbsp;

<ul>
	<li>
	<h5>Diabetes And Obesity</h5>
	</li>
</ul>

<a href="http://merisehat.pk/disease/diabetes-type-1-and-2">Type 1 or Type 2 diabetes</a> can increase the risk of symptoms. A higher body mass index or obesity can also increase the risk.&nbsp;Both diabetes and <a href="https://merisehat.pk/disease/obesity">obesity</a> reduce a person&rsquo;s immunity. Diabetes also increases the risk of infections. However, the risk can be reduced by controlling blood sugar levels through diabetes medications and insulin. If you&rsquo;re overweight, try to lose weight by eating a healthy diet and by exercising regularly. 
&nbsp;

<ul>
	<li>
	<h5>Cancer And Blood Disorders</h5>
	</li>
</ul>

People with cancer are at a higher risk of developing severe symptoms from the illness. However, the risk depends on the type of cancer and the treatment they are getting.

Sickle Cell Anemia also increases the risk. It is an inherited disorder of the RBCs, and the cells die early so oxygen is not transported through the body. It can also cause painful blockages in the small blood vessels.&nbsp;

Thalassemia also makes people prone to serious symptoms. The body does not produce enough hemoglobin in thalassemia, and it negatively affects how the RBCs carry oxygen. 
&nbsp;

<ul>
	<li>
	<h5>Weak Immune System</h5>
	</li>
</ul>

When the immune system is healthy, it fights germs and diseases, but certain conditions can weaken the immune system:

<ul>
	<li>Cancer treatment</li>
	<li>Organ transplant</li>
	<li><a href="https://merisehat.pk/disease/aids">HIV/AIDS</a></li>
	<li>Bone marrow transplant</li>
	<li>Using drugs that weaken the immune system</li>
</ul>

If your immune system is weak, you need to take extra precautions to avoid getting COVID-19.

&nbsp;

<ul>
	<li>
	<h5>CKD And Chronic Liver Disease</h5>
	</li>
</ul>

CKD and Chronic liver disease weaken the immune system and put you at a higher risk of severe symptoms from COVID-19. Moreover, the medications for the treatment of COVID-19 can also have a negative effect on the liver. Dialysis patients should keep their physicians updated on how they feel. 
&nbsp;

Protect yourself and protect others around you with appropriate precautions. Individuals can also check with their local authorities for guidance based on their region. 
&nbsp;

<ul>
	<li>Get vaccinated against COVID.</li>
	<li>Get a booster shot as per recommendations by CDC.</li>
	<li>Maintaining a safe distance, which is at least 1 meter, even if someone does not feel sick or does not have symptoms.</li>
	<li>Wear a mask when in public or at a gathering with multiple people.</li>
	<li>Well ventilated spaces are better than closed ones and if indoors, keep windows open when several people are in the room or space.</li>
	<li>Wash your hands with soap and use a hand sanitizer.</li>
	<li>Cover your nose and mouth with your elbow or a tissue when you sneeze or cough.</li>
	<li>Isolate and quarantine if you are unwell. 
	&nbsp;</li>
</ul>

Seek immediate medical attention if you have difficulty breathing and inform the authorities to protect yourself and others from the virus. Moreover, wear properly fitted masks to protect yourself from the virus, in addition to social distancing and hand hygiene.

&nbsp;

Key Points

<ul>
	<li>COVID-19 is a notification priority disease in Pakistan and authorities should be informed immediately.</li>
	<li>COVID-19 is an acute respiratory infection caused by coronavirus.</li>
	<li>It was declared a global pandemic in March 2020.</li>
	<li>The virus is contracted through the mouth, nose, or eyelids.</li>
	<li>The symptoms vary from person to person.</li>
	<li>Older adults and those with comorbidities are at a higher risk of developing severe symptoms.</li>
</ul>

&nbsp;

[1] Centers for Disease Control and Prevention, 2021. united states covid-19 cases, deaths, and laboratory testing (naats) by state, territory, and jurisdiction.

[2] Blaylock, R.L., 2022. COVID UPDATE: What is the truth?. Surgical Neurology International, 13.

[3] Parasher, A., 2021. COVID-19: Current understanding of its pathophysiology, clinical presentation and treatment. Postgraduate medical journal, 97(1147), pp.312-320.

[4] Tyrrell, D.A. and Myint, S.H., 1996. Coronaviruses. Medical Microbiology. 4th edition.

[5] China, G.P., CDC SARS response timeline.

[6] Al Hajjar, S., Memish, Z.A. and Mcintosh, K., 2013. Middle East respiratory syndrome coronavirus (MERS-CoV): a perpetual challenge. Annals of Saudi medicine, 33(5), pp.427-436.

[7] Mayo Clinic, 2020. COVID‐19: Who's at higher risk of serious symptoms?.

[8] Covid, C.D.C., Team, R., COVID, C., Team, R., COVID, C., Team, R., Bialek, S., Boundy, E., Bowen, V., Chow, N. and Cohn, A., 2020. Severe outcomes among patients with coronavirus disease 2019 (COVID-19)—United States, February 12–March 16, 2020. Morbidity and mortality weekly report, 69(12), p.343.