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Tracking the NYC Legionnaires' outbreak

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Originally published: July 12, 2026; updates ongoing — For important background on the Legionnaires’ disease outbreak on the Upper East Side of Manhattan, read this. For an article highlighting questions that the New York City Department of Health and Mental Hygiene (DOHMH) has not answered, read this.

Data below are from DOHMH. Prior to the July 11 report, DOHMH was only providing what I interpreted to be current hospitalizations as of the day of the report. On July 11, I reached out to DOHMH to point out the importance of providing an “aggregate hospitalized” number (that provides important context, including the percentage of diagnosed patients hospitalized at any point). Later on July 11, DOHMH provided a daily count that began to include “discharged,” which, when added to the “currently hospitalized” number, provided the aggregate hospitalizations. Note: “Discharged” refers only to patients who were admitted to the hospital and then discharged, not those patients who came to an Emergency Department, got a diagnosis and antibiotics, and were released without hospital admission (confirmed by DOHMH spokesperson on July 15).

Jul. 22 clarification: DOHMH explains that the date that DOHMH confirms a case and have it show up on its data page can lag behind the actual date of patient diagnosis. As such, the fact that the count of diagnosed cases has continued to rise is not reflective newly diagnosed cases. Dr. Aister Martin, the DOHMH Commissioner, stated that the “last new diagnosis of Legionnaires’ disease was on Jul. 15.” Jul. 29 clarification: DOHMH stated that, “No cases were diagnosed after 7/21.”

For context of the current aggregate hospitalization percentage, a 2015 Bronx outbreak had an aggregate hospitalization rate of 93 percent; and 2025 Harlem outbreak had an aggregate hospitalization rate of 78 percent.

Summer 2026 Upper East Side Legionnaires’ Disease Outbreak, per DOHMH

DOHMH
Reporting  
Date

Diagnosed  
Cases

Aggregate
Hospitalizations 
(including
deaths)   

% of Diagnosed
Hospitalized 
at any Point
(Aggregate 
Hospitalizations)   

Currently
Hospitalized 

Discharged  

Deaths  

July 30

92

79

85.9

5

67

7

July 29

92

78

84.8

6

66

6

July 28

90

77

85.6

6

65

6

July 27

90

77

85.6

7

65

5

July 26

89

76

85.4

7

64

5

July 25

89

76

85.4

7

64

5

July 23

87

74

85.1

7

62

5

July 22

84

71

84.5

7

59

5

July 21

82

69

84.1

8

56

5

July 20

76

64

84.2

7

53

4

July 19

74

62

83.8

8

51

3

July 18

72

60

83.3

9

50

1

July 17

71

59

83.1

10

48

1

July 16

67

55

82.1

12

43

0

July 15

64

53

82.8

13

40

0

July 14

63

52

82.5

12

40

0

July 13

60

49

81.7

15

34

0

July 12

59

48

81.4

15

33

0

July 11

56

47

83.9

16

31

0

July 10

54

N/A

N/A

18

N/A

0

July 9

46

N/A

N/A

22

N/A

0

July 8

36

N/A

N/A

22

N/A

0

July 6

23

N/A

N/A

17

N/A

0

July 3

10

N/A

N/A

N/A

N/A

0

July 2

2

N/A

N/A

N/A

N/A

0

Source: DOHMH’s Legionnaires’ Disease page. Note: because the page is updated daily, 
only data from the most recent update can be viewed. 

Updated July 15 with DOHMH confirmation of definition of “discharged.”
 

Updated and corrected July 29 so that the category of aggregate hospitalizations properly encompasses deaths.