Coronavirus disease 2019 (COVID-19) is defined as illness caused by a novel coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; formerly called 2019-nCoV), which was first identified amid an outbreak of respiratory illness cases in Wuhan City, Hubei Province, China. [1] It was initially reported to the WHO on December 31, 2019. On January 30, 2020, the WHO declared the COVID-19 outbreak a global health emergency. [2, 3] On March 11, 2020, the WHO declared COVID-19 a global pandemic, its first such designation since declaring H1N1 influenza a pandemic in 2009.Illness caused by SARS-CoV-2 was termed COVID-19 by the WHO, the acronym derived from "coronavirus disease 2019." The name was chosen to avoid stigmatizing the virus's origins in terms of populations, geography, or animal associations.On February 11, 2020, the Coronavirus Study Group of the International Committee on Taxonomy of Viruses issued a statement announcing an official designation for the novel virus: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).The CDC estimates that SARS-CoV-2 entered the United States in late January or early February 2020, establishing low-level community spread before being noticed.Since that time, the United States has experienced widespread infections, with over 97.6 million reported cases and over 1,131,000 deaths reported as of June 8, 2023 as reported by the CDC COVID data tracker. According to the CDC, 75% of people who have died of the virus in the United States as of April 5, 2023 are aged 65 years or older. According to the New York Times, the CDC reports that 1 in 100 older Americans has died from the virus. For people younger than 65, the ratio is about 1 in 1,400. 

Ending the COVID-19 Public Health Emergency and Continued Surveillance

On May 11, 2023, the federal COVID-19 public health emergency (PHE) ended; however, COVID-19 continues to be a health risk.

Going forward, hospitalizations are the main data to track COVID-19 trends by geographic regions in the United States. Additionally, the tracker provides emergency department visits of COVID-19, which is an excellent early indicator of spread. 

A voluntary network of laboratories that submit test data to the CDC will provide valuable information as another early indicator of spread, along with other respiratory diseases (eg, influenza, RSV). 

Additionally, wastewater surveillance provides current levels compared with past levels of infection. 

Monitoring continues for new variants to enable testing of vaccines and therapies for efficacy. 

Early Pandemic Recommendations

Early in the pandemic (April 3, 2020), the CDC issued a recommendation that the general public, even those without symptoms, should wear face coverings in public settings where social-distancing measures were difficult to maintain to abate the spread of COVID-19.

For high-risk individuals, these recommendations remain to avoid infection from COVID-19 and other infections (eg, RSV, influenza). 

The CDC postulated that large numbers of patients could require medical care concurrently, resulting in overloaded public health and healthcare systems and, potentially, elevated rates of hospitalizations and deaths. The CDC advised that nonpharmaceutical interventions (NPIs) are the most important response strategy for delaying viral spread and reducing disease impact. Unfortunately, these concerns were proven accurate. 

The feasibility and implications of suppression and mitigation strategies was rigorously analyzed and was encouraged or enforced by many governments to slow or halt viral transmission. Population-wide social distancing plus other interventions (eg, home self-isolation, school and business closures) are strongly advised. These policies were required for periods to avoid rebound viral transmission.As the United States experienced surges of COVID-19 infections, the CDC intensified its recommendations for transmission mitigation. They recommended all unvaccinated individuals wear masks in public indoor settings. On the basis of evidence regarding emerging variants of concern (See Virology), CDC recommended that persons who were fully vaccinated also wear masks in public indoor settings in areas with substantial or high transmission. Fully vaccinated individuals might consider wearing a mask in public indoor areas, regardless of transmission level, if they or someone in their home was immunocompromised, was at increased risk for severe disease, or was unvaccinated (including young children who were ineligible for vaccination).

Recommendations for high risk individuals remains in place to guard against all infections, including COVID-19. 

The CDC recommended physical distancing, avoiding nonessential indoor spaces, postponing travel until fully vaccinated, enhanced ventilation, and hand hygiene.

According to the CDC, individuals at high risk for infection include persons in areas with ongoing local transmission, healthcare workers caring for patients with COVID-19, close contacts of infected persons, and travelers returning from locations where local spread has been reported.

The CDC has published a summary of evidence of comorbidities that are supported by meta-analysis/systematic review that have a significant association with risk of severe COVID-19 illness. These include the following conditions

  • Cancer 
  • Cerebrovascular disease
  • Chronic kidney disease 
  • COPD (chronic obstructive pulmonary disease) 
  • Diabetes mellitus, type 1 and type 2 
  • Heart conditions (eg, heart failure, coronary artery disease, cardiomyopathies)  
  • Immunocompromised state from solid organ transplant 
  • Obesity (BMI 30 kg/m 2 or greater) 
  • Pregnancy 
  • Smoking, current or former                                              Comorbidities that are supported by mostly observational (eg, cohort, case-control, or cross-sectional) studies include the following
    • Children with certain underlying conditions 
    • Down syndrome 
    • HIV (human immunodeficiency virus) 
    • Neurologic conditions, including dementia 
    • Overweight (BMI 25 to less than 30 kg/m 2) 
    • Other lung disease (including interstitial lung disease, pulmonary fibrosis, pulmonary hypertension) 
    • Sickle cell disease 
    • Solid organ or blood stem cell transplantation 
    • Substance use disorders 
    • Use of corticosteroids or other immunosuppressive medications  

    Comorbidities that are supported by mostly case series, case reports, or, if other study design or the sample size is small include the following:

    • Cystic fibrosis 
      • Thalassemia

      Comorbidities supported by mixed evidence include the following

      • Asthma 
      • Hypertension 
      • Immune deficiencies 
      • Liver disease 

      Such individuals should consider the following precautions:

      • Stock up on supplies.
      • Avoid close contact with sick people.
      • Wash hands often.
      • Stay home as much as possible in locations where COVID-19 is spreading.
      • Develop a plan in case of illness.

      Signs and symptoms

      In a study that included 172 patients diagnosed with COVID-19 in January 2022, the estimated median incubation period was 2.8 days (SD, 1.20) among those infected with the Omicron variant (primarily sublineage BA.1). Most infections fell between 1 and 6 days. The distribution was significantly longer in patients with the Alpha variant (4.5 days), and the researchers’ previous study that used contact tracing data estimated a median incubation period of 3.7 days for the Delta variant.                         The following symptoms may indicate COVID-19 :  

      • Fever or chills (43-45%)
      • Cough (63-83%)
      • Shortness of breath or difficulty breathing (45.6%) 
      • Fatigue (63%)
      • Muscle or body aches (36-63%)
      • Headache (34-70%)
      • New loss of taste (54.2%)  or smell (70.2%)
      • Sore throat (52.9%)
      • Congestion (67.8%) or runny nose (60.1%)
      • Nausea or vomiting (31.6%) 
      • Diarrhea (17.8%) 

       

      Other reported symptoms have included the following:

      • Sputum production
      • Malaise
      • Respiratory distress
      • Neurologic (eg, headache, altered mentality)

      The most common serious manifestation of COVID-19 appears to be pneumonia.

      A complete or partial loss of the sense of smell (anosmia) has been reported as a potential history finding in patients eventually diagnosed with COVID-19 ,however, rates of smell or taste dysruption have decreased as the pandemic has progressed. A study of 616,318 patients with COVID-19 found that 3431 had an associated disturbance in smell or taste; of those, the odds ratios were 0.50 among those infected with the Alpha variant; 0.44 among those infected with Delta; and 0.17 among those infected with Omicron (December 27, 2021–February 7, 2022).

      Diagnosis

      COVID-19 should be considered a possibility (1) in patients with respiratory tract symptoms and newly onset fever or (2) in patients with severe lower respiratory tract symptoms with no clear cause. Suspicion is increased if such patients have been in an area with community transmission of SARS-CoV-2 or have been in close contact with an individual with confirmed or suspected COVID-19 in the preceding 14 days.

      Microbiologic (PCR or antigen) testing is required for definitive diagnosis. 

      Patients who do not require emergency care are encouraged to contact their healthcare provider by phone. Patients with suspected COVID-19 who present to a healthcare facility should trigger infection-control measures. These patients should be evaluated in a private room with the door closed (an airborne infection isolation room is ideal) and instructed to wear a surgical mask. All other standard contact and airborne precautions should be observed, and treating healthcare personnel should wear eye protection.

      Management

      Utilization of programs established by the FDA to allow clinicians access to investigational therapies during the pandemic has been essential. The expanded access (EA) and emergency use authorization (EUA) programs allowed for rapid deployment of potential therapies for investigation and investigational therapies with emerging evidence. A review by Rizk et al describes the role for each of these measures and their importance to providing medical countermeasures in the event of infectious disease and other threats.

      Pharmacologic therapies for COVID-19 disease that have been approved by the FDA or are available by EUA include the following: 

      • Antiviral agents: Remdesivir, nirmatrelvir/ritonavir, and molnupiravir 
      • Corticosteroids: Dexamethasone (or equivalent) for patients who require conventional oxygen 
      • Antithrombotics: Heparin (therapeutic or prophylactic) in hospitalized patients 
      • Immunomodulators: Baricitinib, tocilizumab, abatacept, anakinra, or infliximab for hospitalized patients requiring oxygen 
      • Complement inhibitors: Vilobelimab for hospitalized patients requiring oxygen
      • Vaccines are available to decrease risk of hospitalization and severe disease