Coronavirus infections
Coronavirus infections are caused by viruses in the Coronaviridae family, which can lead to a variety of illnesses affecting the respiratory, gastrointestinal, and occasionally neurological systems. Among these, coronaviruses account for about one-third of common cold cases and can also result in more severe diseases such as viral bronchitis, pneumonia, and notably, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). The COVID-19 pandemic, which began in December 2019, has been a significant global health crisis, with its symptoms ranging from mild respiratory issues to severe complications, including long-term effects known as "long COVID."
Transmission of coronaviruses primarily occurs through respiratory droplets from coughing or sneezing and can also spread via contact with contaminated surfaces. Certain groups, including older adults and individuals with underlying health conditions, are at greater risk for severe outcomes. Prevention methods emphasize good hygiene practices, including handwashing and social distancing, alongside the use of face masks during outbreaks.
Currently, there are effective treatments for COVID-19, and vaccination efforts have led to a significant portion of the population being vaccinated against the virus. Public health measures have focused on minimizing contact with infected individuals to curb the spread of these highly contagious viruses. Understanding the nature of coronavirus infections is key to managing and preventing their impact on public health.
Coronavirus infections
Anatomy or system affected:Gastrointestinal system, lungs, respiratory system
Also known as: Common cold, coronavirus 2019 (COVID-19), Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), viral bronchitis, viral pneumonia
Definition
The Coronaviridae family includes some of the largest known positive-strand ribonucleic acid (RNA) viruses. Exposure to coronaviruses can result in a variety of infections, including approximately one-third of all cases of the common cold. Other diseases caused by coronaviruses include forms of viral bronchitis and pneumonia, especially in persons with weakened immune systems, as well as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). A new coronavirus disease, coronavirus disease 2019 (COVID-19), was first reported in Wuhan, China, in December 2019. By March 2020, COVID-19 had become a global pandemic.
Causes
Coronaviruses are the underlying cause of a variety of illnesses that affect the respiratory system, the gastrointestinal system, and, in rare cases, the neurological system. Infections with the virus are often seasonal in nature, with more occurring in winter. Contact with contaminated droplets from sneezing and coughing and direct contact by touching contaminated objects, such as surfaces and tissues, may transmit the virus from person to person. With COVID-19, contaminated droplets may remain airborne even after a person who is infected with the virus has left the area.
The virus may live six to nine hours, and the live virus has been found in the stool of people diagnosed with SARS. It is highly contagious, and reinfection may occur. The virus can affect humans, cattle, pigs, rodents, cats, dogs, and birds, but instances of animal-to-human coronavirus infections, such as SARS and MERS, are rare. While COVID-19 is suspected to have started as an animal coronavirus that spread to humans, its exact origins are still unclear.
Risk Factors
The main risk factor for coronavirus infection is exposure to an infected person. Especially close proximity activities with an infected person, such as sharing living space, sharing food or utensils, or kissing, heighten the risk. Contact with droplets or contaminated surfaces containing the virus even in the absence of an infected person can also lead to transmission.
The risk of severe infection increases if a person is immunocompromised (less able to fight infections because of a weakened immune system). With COVID-19, older people are at an elevated risk. Those over 65 are 81 percent more likely to die from infection. Also, individuals with serious or chronic medical conditions including heart disease, cancer, diabetes, and lung or kidney disease are at greater risk of becoming very ill if they are infected with the virus.
Symptoms
Coronavirus infection that leads to the common cold comes with symptoms of fatigue, a scratchy throat, sneezing, nasal congestion, and a runny nose. Fever rarely occurs with a cold, except in children. A more serious infection, such as pneumonia or SARS, may be occurring if symptoms include fever, chills, muscle aches, an acute cough, a headache, dizziness, or diarrhea. COVID-19 symptoms may develop within fourteen days of exposure and may include cough, fever, and shortness of breath. Some people with COVID-19 may have mild symptoms or be asymptomatic. Others experience long-term effects, or long covid, with symptoms such as brain fog, fatigue, or breathing difficulties which last years.
Screening and Diagnosis
A physical examination including listening to lung sounds, reviewing symptoms, chest x-rays, and blood work may be used to determine if a person has a cold or has developed pneumonia or SARS. Blood work may include blood chemistries and a complete blood count to determine if white blood cell counts, lymphocytes, and platelets are low. Specific tests for SARS may be ordered. COVID-19 can be diagnosed using a Nucleic Acid Amplification Test (often a laboratory performed PCR) or an Antigen Test (rapid and often at-home test).
Treatment and Therapy
There is no immediate cure for a coronavirus infection. Instead, treatment focuses on symptoms. In the absence of fever, symptoms may be treated with over-the-counter medications, plenty of fluids, and rest. If symptoms worsen or if a fever develops, one should seek medical care. Antibiotics, antiviral medications, and high doses of steroids to decrease lung inflammation may be prescribed. In severe cases, the patient may need oxygen, breathing support with a respirator, and hospitalization. In 2020, the drugs dexamethasone, favilavir, remdesivir, bamlanivimab, and REGEN-COV2 were approved as COVID-19 treatments. In February 2023, the CDC reported three antiviral treatments for the general public—Nirmatrelvir with Ritonavir (Paxlovid), Remdesivir (Veklury), and Molnupiravir (Lagevrio)—and one treatment for immunocompromised individuals—convalescent plasma.
For cases of suspected COVID-19 exposure and infection, the Centers for Disease Control and Prevention (CDC) recommends calling one's health care provider ahead of seeking care, noting that those with mild cases of the illness are able to recover at home and that staying home except to get medical care will prevent the spread of the virus. For those with worsening symptoms, such as difficulty breathing, it is essential to get care and to call one's doctor or emergency room ahead of arrival. In such cases, the CDC also advises staying at least six feet (about two meters) away from others, wearing a facial covering, and avoiding public transportation, taxis, or ride-sharing services.
Prevention and Outcomes
The best prevention against coronavirus infection is to limit contact with infected persons. Hand hygiene, including frequent handwashing with soap and water or cleaning hands with an alcohol-based hand sanitizer with at least 60 percent alcohol, is an important part of prevention. The CDC recommends washing with soap and water for at least twenty seconds after blowing one's nose, coughing, or sneezing; after going to the bathroom; and before preparing food or eating. Avoid touching the eyes, nose, and mouth with unwashed hands. Cough or sneeze into tissue or into the arm to minimize droplets and airborne particles. Used tissues should be disposed of in a lined trash can. Because coronaviruses are contagious, those who are sick should not share food and drink, utensils, bedding, towels, or personal supplies with others in the home. High-touch household areas, including doorknobs, counter tops, and other surfaces, should be cleaned routinely with disinfectant by those who are not infected.
With a novel coronavirus pandemic like COVID-19, all of these preventative measures are essential to limiting its spread and mitigating its negative impacts. Public health and government officials urged the widespread use of social distancing—staying home whenever possible and maintaining a distance of six feet (two meters) from others when it is necessary to go out—during the COVID-19 outbreak. Additionally, those who are ill with COVID-19 should stay home unless they need medical care; wear a face mask if they are able to and need to go out; stay in a designated sick room; and use a separate bathroom if possible. As there is evidence of human-to-animal spread of COVID-19, the CDC recommends that those who are ill with the virus find someone to care for their pets or else wash their hands before and after contact.
There are no vaccines for most coronavirus infections. However, the global COVID-19 pandemic led to a massive international effort to develop a vaccine as fast as possible. The earliest approved vaccines were released on a limited basis in China and Russia in mid-2020, though these had not undergone the vigorous testing vaccines are typically subject to, and some health experts warned the risks associated with rushing out vaccines too quickly. In the United States, the first vaccines were approved for emergency use in December 2020. By May 2021, 132.76 million Americans (40 percent of the population) were fully vaccinated. In 2022, more vaccines were approved for use in the US—two mRNA (Pfizer-BioNTech and Moderna), one protein subunit vaccine (Novavax), and one viral vector vaccine (Johnson & Johnson’s Janssen). By March 2023, 269.55 million Americans (81 percent of the population) had received at least one dose of the vaccine and 230.08 million (69 percent of the population) were fully vaccinated.
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