Patients with SARS-C0V-2 infection can experience a range of clinical manifestations, from no symptoms to critical illness. Patients who are older or who have underlying medical conditions are at higher risk of progressing to severe COVID-19, especially if they are unvaccinated or under vaccinated.
Symptoms commonly reported among adults with COVID-19 include:
Signs and symptoms of COVID-19 in children vary by age of the child and are usually milder compared to adults.
See NIH Clinical Spectrum of SARS-CoV-2 Infection for a more detailed discussion of COVID-19 clinical signs and symptoms including severity of illness categories.
Case Classification
Suspect
Meets supportive laboratory evidence†† with no prior history of being a confirmed or probable case.
†† For suspect cases, jurisdictions may opt to place them in a registry for other epidemiological analyses or investigate to determine probable or confirmed status.
Probable
Meets clinical criteria AND epidemiologic linkage with no confirmatory or presumptive laboratory evidence for SARS-CoV-2, OR
Meets presumptive laboratory evidence, OR
Meets vital records criteria with no confirmatory laboratory evidence for SARS-CoV-2.
Confirmed
Meets confirmatory laboratory evidence.
Clinical Criteria
In the absence of a more likely diagnosis:
Acute onset or worsening if at least two of the following symptoms or signs:
fever (measured or subjective),
chills,
rigors,
myalgia,
headache,
sore throat,
nausea or vomiting,
diarrhea,
fatigue,
congestion or runny nose.
OR
Acute onset or worsening of any one of the following symptoms or signs:
cough,
shortness of breath,
difficulty breathing,
olfactory disorder,
taste disorder,
confusion or change in mental status,
persistent pain or pressure in the chest,
pale, gray, or blue colored skin, lips, or nail beds, depending on skin tone,
inability to wake or stay awake.
OR
Severe respiratory illness with at least one of the following:
Clinical or radiographic evidence of pneumonia,
Acute respiratory distress syndrome (ARDS).
Laboratory Criteria
Confirmed laboratory evidence:
Presumptive laboratory evidence:
Supportive laboratory evidence:
Human
Nasal and pharyngeal secretions.
Omicron is very infectious. More transmissible than original SARS-CoV-2 and Delta variant. Anyone with Omicron infection, regardless of vaccination status or whether or not they have symptoms, can spread the virus to others. Data suggest that Omicron can cause reinfection, even in people who have recovered from COVID-19. See CDC Variants of the Virus.
There are three principal ways in which infectious exposures to respiratory fluids carrying SARS-CoV-2 occur:
Inhalation plays a larger role than previously believed, as aerosolized particles can remain in the air for minutes to hours. This is more likely in enclosed spaces with poor ventilation, especially if an infectious person spends an extended period in that space or if they are participating in activities that increase exhalation of respiratory fluids, such as vigorous exercise, singing, or shouting.
Read CDC's Scientific Brief: SARS-CoV-2 Transmission.
For CDC patient-friendly information, see How COVID-19 Spreads.
CDC has been
monitoring the emerging science on when
and for how long a person is maximally
infectious with Omicron.
Per CDC, SARS-CoV-2 transmission occurs early in the course of infection. Infectiousness peaks around one day before symptom onset and declines within a week of symptom onset, with an average period of infectiousness and risk of transmission between 2-3 days before and 8 days after symptom onset. These data are from studies of prior SARS-CoV-2 variants, including Delta.
A person
with COVID-19 is considered to be
infectious beginning 2 days before their
symptoms began until their isolation
period ends. If they test positive for
COVID-19 but remain asymptomatic, they
are considered to be infectious from 2
days before the test was collected until
their isolation ends.
When
isolation can end:
Everyone with
COVID-19 must isolate for at least 5
days.
For the general public, see Isolation Instructions for People with COVID-19.
* The CDC
recommends extending isolation for
patients who were severely ill or who
are moderately to severely
immunocompromised.
For patients
with severe
to critical COVID-19 illness (e.g.,
required hospitalization, intensive
care, or ventilation support) who are
not immunocompromised, the CDC
recommends extending the duration of
isolation and precautions from 10 days
to up to 20 days from illness onset.
This is because they may produce
replication-competent virus beyond 10
days.
For patients
who are moderately
to severely immunocompromised (regardless
of symptoms or COVID-19 illness
severity) the CDC recommends an
isolation period of at least 20 days,
ending isolation in conjunction with a
test-based strategy and consultation
with an infectious disease specialist
and infection control experts. to
determine the appropriate duration of
isolation and precautions. This is
because moderately or severely
immunocompromised patients may produce
replication-competent virus beyond 20
days.
A close contact is a person with exposure to a laboratory-confirmed or clinical case of COVID-19 during the period of infectiousness of the case (see Communicability/Period of Infectiousness above). This is from 2 days before symptom onset (or date of first positive lab test for asymptomatic persons) until the case meets criteria for discontinuing isolation/transmission-based precautions.
Effective October 14,, 2022, by order of the State Public Health Officer, who is considered a close contact varies based on the size of the shared indoor space:
For additional details see CDPH Order Q&A.
People are considered close contacts regardless of the use of face masks by the case or contact. Exception: Cal/OSHA states that employees are not a close contact if they wore a respirator required by the employer and used in compliance with section 5144, whenever they were sharing the same airspace of the COVID-19 case while they were infectious.
See site specific B73 for more specific guidance on determining close contacts in different settings.
For general public, see Instructions for Close Contacts at ph.lacounty.gov/covidcontacts.
See the NIH COVID-19 Treatment Guidelines for comprehensive information and the National Institutes of Health have published interim guidelines for the medical management of COVID-19 prepared by the COVID-19 Treatment Guidelines Panel. Providers should make treatment decisions based on currently available evidence.
Pre-exposure prophylaxis with
Evusheld (Tixagevimab/cilgavimab) is available for
individuals who are moderately or severely immunocompromised
or those for whom COVID-19 vaccination is not recommended
due to history of severe adverse reaction.
See LAC DPH outpatient therapeutics resources:
For providers: ph.lacounty.gov/covidtherapeutics
For public: ENGLISH: ph.lacounty.gov/covidmedicines and Spanish: ph.lacounty.gov/covidmedicamentos
Natural immunity: Natural immunity from prior SARS-CoV-2 viral variants does not appear to be protective against Omicron subvariants. Among other human coronaviruses, reinfection appears to occur variably over time after onset of infection. The likelihood of re-infection is expected to increase over time because of waning immunity and the possibility of exposure to virus variants. In addition, the level of protection after infection may vary depending on how mild or severe the illness was as well as the person's age.
Vaccine-induced immunity: Currently authorized COVID-19 vaccines remain effective at preventing severe illness, hospitalization, and death against SARS-CoV2 including Omicron. While efficacy wanes over time, booster doses restore vaccine efficacy for severe outcomes. See CDC COVID-19 Vaccine Effectiveness.
See CDC Science Brief-Immune Response to Infection and Vaccination
Clinical and epidemiologic histories are required to aid in diagnosis. Direct viral detection methods with sensitive molecular tests (e.g. RT-PCR) are recommended for diagnosing current infection with SARS-CoV-2. Antigen tests and over the counter (OTC) self-tests can also be used to diagnose acute infection but they are less accurate than PCR tests.
When using lower sensitivity assays (e.g., antigen tests, some molecular tests, OTC self-tests), negative results are considered presumptive and confirmation with RT-PCR is recommended, especially if important for clinical management or infection control.
Serological testing is not a standard part of outbreak investigation.
See CDC Testing for SARS-CoV-2 Infection for an overview of test types.
Facilities are encouraged to test through a commercial lab. Facilities should follow the specimen collection and pick-up instructions as per the facility’s designated commercial clinical laboratory. They should work directly with the clinical laboratory for all questions regarding specimen collection and transport.
See Laboratories Providing Diagnostic Testing for resources to support organizations identify a laboratory provider that best fits their needs.
PHL SARS CoV-2 PCR Specimen Collection
Upper Respiratory Specimen--for initial diagnostic testing, collect at least one upper respiratory specimen.
Any of the following specimens are acceptable:
Swabs: Acceptable swab types include synthetic fiber swabs (flocked or spun polyester) with plastic or wire shafts. Do not use calcium alginate swabs or cotton swabs with wooden shafts. Place swab in a minimum of 1-3 mL viral transport media, liquid Amies, or saline.
Aspirates and washes: collect 1.5-3.0 mL in a sterile, leak-proof container.
Lower respiratory tract specimens--may be required for patients presenting with severe disease or fatal cases. Acceptable lower respiratory tract specimens include sputum, bronchoalveolar lavage, tracheal aspirate, pleural fluid, lung swab, or lung biopsy. Collect lower respiratory tract specimens in a sterile, leak-proof container. Lung swab should be submitted in viral transport media. A minimum of 2-3 mL is needed for sputum, lavage and aspirates.
Storage: Refrigerate specimens at 2-8°C and transport on cold pack. If specimen storage exceeds 3 days, freeze specimen at ≤ -70°C and ship on dry ice.
For more information see:
A person is considered up to date with their COVID-19 vaccines when they have received all recommended doses in the primary series AND have received all recommended booster doses, when eligible. See COVID-19 Vaccine Schedules.
See CDC Stay Up to Date with Your COVID-19 Vaccines Including Boosters
A patient with a history of recent recovery from COVID-19 is defined as a person with a positive viral COVID-19 test within the past 3 months (90 days) who has recovered from the previous infection. Recovered means they are no longer considered infectious (i.e., their isolation period has ended).
If the patient had symptoms with their most recent infection, the 90 days are from the onset of the initial COVID-19 symptoms. If they never had symptoms, then the 90 days are from the date of collection of the first positive viral COVID-19 test.
If the recently recovered person
Is asymptomatic
Develops new symptoms consistent with COVID-19 illness
Rationale:
Immunocompetent patients who have recovered from acute COVID-19 infection can continue to have detectable SARS-CoV-2 RNA in upper respiratory specimens for 3 months after illness onset and persistent positive antigen tests are possible for at least 24 days. Replication-competent virus has not been reliably recovered from such patients, and they are not likely infectious.
Antigen testing of asymptomatic close contacts is recommended to identify a new infection if 31-90 days have passed since their first positive test. This is because persistent antigen positivity is unlikely after a month and because the probability of SARS-CoV-2 reinfection increases with time due to exposure to viral variants and waning immunity.
Note: PDF documents on this site were created using Adobe Acrobat 5.0 or later. Document functionality may be reduced if you are using an earlier version (4.x or less). Get the latest version of Adobe Acrobat.
Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.
