734. Post-exposure Management of Influenza in Roommates at a Tertiary Care Cancer Center
Session: Poster Abstract Session: Respiratory Infections: Viral
Thursday, October 4, 2018
Room: S Poster Hall
Background: Post-exposure antiviral chemoprophylaxis with neuraminidase inhibitors (NI) is 80% effective in preventing influenza in household members. In hospital settings, management of exposed roommates has not been specifically addressed in clinical studies. Some experts recommend immunocompromised individuals exposed to influenza to receive therapeutic doses of NI as a preventive measure regardless of duration of exposure.

Aim: To determine optimal intervention in high risk patients exposed to influenza based on duration of spatial overlap and viral testing at the time exposure is recognized.

Methods: MSK is a 473-bed tertiary care cancer center. Infection Control performs contact investigation for cases diagnosed with influenza including baseline testing of exposed roommates using a multiplex PCR test. The primary team is notified of exposures and makes recommendations regarding prophylaxis. Retrospective review of patients considered exposed to influenza during 3 seasons was performed. Information on spatial overlap, prophylaxis, and viral testing was extracted.

Results: Out of 64 patients exposed, 5 (8%) developed influenza (Table). Baseline testing was done in 51 (80 %): none with overlap of < 4 days were symptomatic or tested positive; 2/12 with overlap > 4 days tested positive. Attack rate for those with exposure time < 4 days who did not receive prophylaxis was 2.6 %. No breakthrough infection occurred in the prophylaxis group. Post exposure follow up revealed 2 more cases for those overlapping > 4 days; a single case of breakthrough infection developed at 7 days, resistance testing was not performed, and patient responded to therapeutic doses of NI without persistent shedding.

Conclusion: Duration of overlap in semi-private rooms correlates with secondary cases of influenza. Prophylactic doses of NI are safe and effective for asymptomatic individuals with exposure < 4 days to index case. For patients with spatial overlap > 4 days, baseline testing is recommended to recognize cases early and interrupt nosocomial transmission.

Overlap Duration

Exposed Number

Prophylaxis Administered

Tested at Baseline

Attack rate %

(Prophylaxis group)

Attack rate %

(No Prophylaxis group)

< 2 Days


9 (26%)

28 (82%)


4 % (1)

2-4 Days


5 (28%)

15 (83%)



> 4 Days


6 (50%)

8 (67%)

16% (1)

50% (3)

Sandra Carlino, BS, Infection Control, Memorial Sloan Kettering Cancer Center, New York, NY and Mini Kamboj, MD, Memorial Sloan Kettering Cancer Center, New York, NY


S. Carlino, None

M. Kamboj, None

Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 3rd with the exception of research findings presented at the IDWeek press conferences.