All data are preliminary and may change as more reports are received.
A description of the surveillance systems summarized in COVIDView, including methodology and detailed descriptions of each data component, is available on the surveillance methods page.
- CDC has modified existing surveillance systems, many used to track influenza and other respiratory viruses annually, to track COVID-19.
- Nationally, the percentage of laboratory specimens testing positive for SARS-CoV-2 continued to increase.
- Visits to outpatient providers and emergency departments (EDs) for illnesses with symptoms consistent with COVID-19 are elevated compared to what is normally seen at this time of year but decreased compared to levels reported last week. At this time, there is little influenza virus circulation. The levels of people presenting for care with these symptoms is likely due to COVID-19 but may be tempered by a number of factors including less ILI overall because of widespread adoption of social distancing efforts and changes in healthcare seeking behavior.
- The overall cumulative COVID-19 associated hospitalization rate is 20.0 per 100,000, with the highest rates in persons 65 years and older (63.8 per 100,000) and 50-64 years (32.8 per 100,000). Hospitalization rates for COVID-19 in older people are higher than what is typically seen early in a flu season.
- Based on death certificate data, the percentage of deaths attributed to COVID-19, pneumonia or influenza increased from 17.8% during week 14 to 18.8% during week 15.
The number of specimens tested for SARS-CoV-2 and reported to CDC by public health laboratories and a subset of clinical and commercial laboratories in the United States are summarized below. At this point in the outbreak, all laboratories are performing primary diagnostic functions; therefore, the percentage of specimens testing positive across laboratory types can be used to monitor trends in COVID-19 activity. As the outbreak progresses, it is possible that different types of laboratories will take on different roles, and the data interpretation may need to be modified. The lower percentage of specimens testing positive in the clinical laboratories compared to the public health and commercial laboratories is likely due to the amount of COVID-19 activity in areas with reporting laboratories and a larger proportion of specimens from children.
| Week 15 (April 5 – April 11, 2020) |
Cumulative since March 1, 2020 | |
|---|---|---|
| No. of specimens tested | 680,213 | 2,313,702 |
| Public Health Laboratories | 75,654 | 319,885 |
| Clinical Laboratories | 41,136 | 155,531 |
| Commercial Laboratories | 563,423 | 1,838,286 |
| No. of positive specimens | 145,764 (21.4%) | 426,459 (18.4%) |
| Public Health Laboratories | 13,466 (17.8%) | 47,549 (14.9%) |
| Clinical Laboratories | 4,720 (11.5%) | 12,380 (8.0%) |
| Commercial Laboratories | 127,578 (22.6%) | 366,530 (19.9%) |
* Commercial and clinical laboratory data represents select laboratories and does not capture all tests performed in the United States.
Public Health Laboratories
Clinical Laboratories
Commercial Laboratories
* Commercial laboratories began testing for SARS-CoV-2 in early March, but the number and geographic distribution of reporting commercial laboratories became stable enough to calculate a weekly percentage of specimens testing positive as of March 29, 2020.
Additional virologic surveillance information: Surveillance Methods
Two syndromic surveillance systems are being used to monitor trends in outpatient and emergency department visits that may be related to COVID-19. Each system monitors a slightly different syndrome, and together these systems provide a more comprehensive picture of mild to moderate COVID-19 illness than either would individually. Both systems are currently being affected by recent changes in healthcare seeking behavior, including increasing use of telemedicine and recommendations to limit emergency department (ED) visits to severe illness, as well as increased social distancing. These changes affect the numbers of people and their reasons for seeking care in the outpatient and ED settings.
ILINet
The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) provides data on visits for influenza-like illness (ILI) (fever [≥100○F] and cough and/or sore throat) to approximately 2,600 primary care providers, emergency departments and urgent care centers in all 50 states, Puerto Rico, the District of Columbia and the U.S. Virgin Islands. Mild COVID-19 illness presents with symptoms similar to ILI, so ILINet is being used to track trends of mild to moderate COVID-19 illness and allows for comparison with prior influenza seasons.
Nationwide during week 15, 2.9% of patient visits reported through ILINet were due to ILI. This percentage is above the national baseline of 2.4% but represents the third week of a decline after three weeks of increase beginning in early March. The percentage of visits for ILI decreased in all age groups. Nationally, laboratory confirmed influenza activity as reported by clinical laboratories decreased to levels usually seen in summer months which, along with changes in healthcare seeking behavior and the impact of social distancing, is likely driving the decrease in ILI activity.
* Age-group specific percentages should not be compared to the national baseline.
On a regional levelexternal icon, the percentage of outpatient visits for ILI ranged from 1.3% to 8.3% during week 15; all regions reported a decreased percentage of outpatient visits for ILI compared to week 14 and five regions are below their region-specific baselines.
ILI Activity Levels
Data collected in ILINet are used to produce a measure of ILI activity for all 50 states, Puerto Rico, the District of Columbia and New York City. The mean reported percentage of visits due to ILI for the current week is compared to the mean reported during non-influenza weeks, and the activity levels correspond to the number of standard deviations below, at or above the mean.
The number of jurisdictions at each activity level during week 15 and the change compared to the previous week are summarized in the table below and shown in the following maps. The decreasing percentage of visits for ILI described above are reflected in this week’s ILI activity levels.
| Activity Level | Number of Jurisdictions | |
| Week 15 (Week ending April 11, 2020) |
Compared to Previous Week | |
| Very High | 2 | -6 |
| High | 10 | -4 |
| Moderate | 6 | +2 |
| Low | 11 | -1 |
| Minimal | 24 | +9 |
| Insufficient Data* | 1 | No change |
*Data collected in ILINet may disproportionally represent certain populations within a state, and may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.