nosocomial h1n1 infection during 2010–2011 pandemic: a retrospective cohort study from a tertiary...

4
Short report Nosocomial H1N1 infection during 2010e2011 pandemic: a retrospective cohort study from a tertiary referral hospital q T. Veenith a , F. Sanfilippo b, c , A. Ercole a , E. Carter b , N. Goldman a , P.G. Bradley a , K. Gunning a , R.M. Burnstein b, * a John Farman Intensive Care Unit, Cambridge University Hospitals NHS Trust, Cambridge, UK b Neuro Critical Care Unit, Cambridge University Hospitals NHS Trust, Cambridge, UK c Department of Experimental and Clinical Pharmacology, University of Catania, School of Medicine, Catania, Italy A RT I C L E I N F O Article history: Received 11 January 2012 Accepted 9 April 2012 Available online 1 June 2012 Keywords: Critical care unit H1N1 Hospital-acquired H1N1 influenza Vaccine SUMM ARY This study aimed to estimate the incidence of hospital transmission of influenza A subtype H1N1 [A(H1N1)], to identify high-risk areas for such transmission and to evaluate common characteristics of affected patients. In this single-centre retrospective cohort study, 10 patients met the criteria for hospital-acquired A(H1N1) infection over a three-month period. All affected patients required an escalation of their care and the mortality rate was 20%. Clinicians should be aware of the risk of nosocomial A(H1N1) infection that exists despite routine infection control measures and should consider additional control measures including vaccination of hospital inpatients and healthcare staff. Ó 2012 Published by Elsevier Ltd on behalf of the Healthcare Infection Society. Introduction The A(H1N1) pandemic influenza virus is a product of the triple reassortment of human, avian and swine H1N1 viruses and can cause severe respiratory failure. 1 Nosocomial trans- mission of influenza is a recognized problem for vulnerable patients including paediatric, immunosuppressed, haem- oncological patients and the elderly. A(H1N1) influenza is spread by bio-aerosols (<5 mm diameter) and droplets (20 mm diameter), which may be generated in the hospital environ- ment by cough, chest physiotherapy and ventilation. 2 These aerosols can travel >2 m and are detectable for up to 24 h after their release. Influenza virus can survive on non-porous surfaces for 24e48 h, on porous surfaces for up to 12 h and on the hands of care providers for up to 5 min. 2 This study aimed to estimate the incidence of hospital transmission of A(H1N1), to identify the high-risk areas for transmission, and to assess any common characteristics of affected patients. Methods The National Research Ethics Committee reviewed this retrospective cohort study and a waiver of consent was issued (Ref.: 04/02). The study included all inpatients in a tertiary referral hospital (Cambridge University Hospitals NHS Trust) between November 2010 and January 2011 who had a positive A(H1N1) polymerase chain reaction (PCR). Data obtained from the medical notes and general practitioners included patient demography, medical history, A(H1N1) influenza vaccination q Presented and elected as best free research paper in State of Art Meeting, London, 2011. * Corresponding author. Address: Neuro Critical Care Unit, Cambridge University Hospitals NHS Trust, Hills Road, Cambridge CB2 0QQ, UK. E-mail address: [email protected] (R.M. Burnstein). Available online at www.sciencedirect.com Journal of Hospital Infection journal homepage: www.elsevierhealth.com/journals/jhin 0195-6701/$ e see front matter Ó 2012 Published by Elsevier Ltd on behalf of the Healthcare Infection Society. doi:10.1016/j.jhin.2012.04.010 Journal of Hospital Infection 81 (2012) 202e205

Upload: t-veenith

Post on 04-Sep-2016

217 views

Category:

Documents


4 download

TRANSCRIPT

ww.sciencedirect.com

Journal of Hospital Infection 81 (2012) 202e205

Available online at w

Journal of Hospital Infection

journal homepage: www.elsevierhealth.com/journals / jh in

Short report

Nosocomial H1N1 infection during 2010e2011pandemic: a retrospective cohort study from a tertiaryreferral hospitalq

T. Veenith a, F. Sanfilippo b,c, A. Ercole a, E. Carter b, N. Goldman a,P.G. Bradley a, K. Gunning a, R.M. Burnstein b,*

a John Farman Intensive Care Unit, Cambridge University Hospitals NHS Trust, Cambridge, UKbNeuro Critical Care Unit, Cambridge University Hospitals NHS Trust, Cambridge, UKcDepartment of Experimental and Clinical Pharmacology, University of Catania, School of Medicine, Catania, Italy

A R T I C L E I N F O

Article history:Received 11 January 2012Accepted 9 April 2012Available online 1 June 2012

Keywords:Critical care unitH1N1Hospital-acquired H1N1influenzaVaccine

q Presented and elected as best free reseaMeeting, London, 2011.* Corresponding author. Address: Neuro

Cambridge University Hospitals NHS Trust, Hi0QQ, UK.

E-mail address: [email protected] (R.M. B

0195-6701/$ e see front matter � 2012 Publdoi:10.1016/j.jhin.2012.04.010

S U M M A R Y

This study aimed to estimate the incidence of hospital transmission of influenza A subtypeH1N1 [A(H1N1)], to identify high-risk areas for such transmission and to evaluate commoncharacteristics of affected patients. In this single-centre retrospective cohort study, 10patients met the criteria for hospital-acquired A(H1N1) infection over a three-monthperiod. All affected patients required an escalation of their care and the mortality ratewas 20%. Clinicians should be aware of the risk of nosocomial A(H1N1) infection that existsdespite routine infection control measures and should consider additional controlmeasures including vaccination of hospital inpatients and healthcare staff.

� 2012 Published by Elsevier Ltd on behalf of the Healthcare Infection Society.

Introduction

The A(H1N1) pandemic influenza virus is a product of thetriple reassortment of human, avian and swine H1N1 virusesand can cause severe respiratory failure.1 Nosocomial trans-mission of influenza is a recognized problem for vulnerablepatients including paediatric, immunosuppressed, haem-oncological patients and the elderly. A(H1N1) influenza isspread by bio-aerosols (<5 mm diameter) and droplets (�20 mmdiameter), which may be generated in the hospital environ-ment by cough, chest physiotherapy and ventilation.2 These

rch paper in State of Art

Critical Care Unit,lls Road, Cambridge CB2

urnstein).

ished by Elsevier Ltd on beha

aerosols can travel>2 m and are detectable for up to 24 h aftertheir release. Influenza virus can survive on non-poroussurfaces for 24e48 h, on porous surfaces for up to 12 h andon the hands of care providers for up to 5 min.2 This studyaimed to estimate the incidence of hospital transmission ofA(H1N1), to identify the high-risk areas for transmission, and toassess any common characteristics of affected patients.

Methods

The National Research Ethics Committee reviewed thisretrospective cohort study and a waiver of consent was issued(Ref.: 04/02). The study included all inpatients in a tertiaryreferral hospital (Cambridge University Hospitals NHS Trust)between November 2010 and January 2011 who had a positiveA(H1N1) polymerase chain reaction (PCR). Data obtained fromthe medical notes and general practitioners included patientdemography, medical history, A(H1N1) influenza vaccination

lf of the Healthcare Infection Society.

Table I

Characteristics of patients with hospital-acquired A(H1N1) influenza

Patientno.

Age(years)

LOS inhospital(days)

ITU/HDUadmission

Immunodeficiency Medical history Sex LOS beforePCR/symptoms

Outcome Vaccinationstatus

Antiviraltherapy

Escalationof treatment

1 67 32 HDU Yes: radiotherapy Plasmacytoma undergoingradiotherapy

M 5 days Died No Yes Yes

2 79 12 HDU Yes: steroids Admitted with bilateralpulmonary embolism,on steroids for polymyalgiarheumatic

F 6 days Discharged Yes Yes Yes

3 27 53 ITU/HDU No Admitted with Budd Chiari,past history of nephroticsyndrome

M 6 days Discharged No Yes Yes

4 68 90 ITU No Admitted with acute orchronic liver failure

M 9 days Died No Yes No

5 44 71 ITU No Multiple sclerosis admittedwith urosepsis, treated thendeveloped sudden respiratoryfailure requiring CPAP

F 10 days Discharged Yes Yes Yes

6 21 77 HDU Yes:immunosuppressants

Post-stem-cell transplant foranaplastic large cell lymphoma

M 12 days Discharged No Yes Yes

7 44 75 ITU Yes: steroids Acute renal failure secondaryto vasculitis (ANCA positive)

M 12 days Discharged No Yes No

8 29 45 ITU Yes: post transplant Admitted for orthotopic livertransplant (sclerosing cholangitis),acute rejection followed by redosurgery

M 25 days Discharged No Yes No

9 42 84 ITU No Admitted with epidural abscess andC6e7 discitis with cord compression,operated

F 28 days Rehabilitation No Yes No

10 57 62 ITU No Post-cardiac surgery following anacute MI, coronary bypass graft andmitral valve replacement

M 49 days Discharged No Yes No

HDU, high dependency unit; ITU, intensive therapy unit; LOS, length of stay; PCR, polymerase chain reaction; CPAP, continuous positive airways pressure; ANCA, anti-neutrophilcytoplasmic antibodies; MI, myocardial infarction.

T.Veenith

etal.

/Jo

urnalofHospita

lInfectio

n81

(2012)202

e205

203

T. Veenith et al. / Journal of Hospital Infection 81 (2012) 202e205204

history, relevant timelines, treatments given during thisadmission and outcome.

Hospital-acquired A(H1N1) influenza [HA-A(H1N1)] wasdefined as a positive PCR with symptoms after admission withan unrelated illness, after the incubation period suggested bythe Centers for Disease Control and Prevention (1e4 days) andwithout any ‘flu-like’ symptoms on admission. To exclude falsepositives for HA-A(H1N1), the longest incubation period (fivedays) was used as the minimum duration between hospitaladmission and PCR positivity. Patients included were followedup for the next three months to ascertain the outcome fromtheir hospital admission. Escalation of treatment was definedas a transfer from a non-critical care area to a critical carearea. Patients were considered immunosuppressed if they weretaking immunosuppressant or anti-rejection drugs, undergoingplasmapheresis, radiotherapy or chemotherapy.

Results

Between November 2010 and January 2011, 86 patientswere identified with (reverse transcriptase PCR) influenzaA(H1N1) infection. Of these 86 patients, 10 (12%) patients metthe criteria for HA-A(H1N1) (Figure 1). The ages of the patientswith HA-A(H1N1) ranged from 21 to 79 years (median: 44). Eight(80%) patients had serious underlying illnesses and five (50%)were receiving immunosuppressive therapy. Seven (70%) of thepatients were admitted for medical treatment of acuteillnesses or ongoing management of their underlying illnessesand the other three patients were admitted for surgicalprocedures.

The length of hospital admission prior to symptoms andpositive PCR varied from 5 to 49 days (median: 11). Seven (70%)patients developed HA-A(H1N1) infection more than 7 daysafter admission. Five (50%) patients acquired A(H1N1) infectionwhile in a critical care unit and all needed an escalation orprolongation of intensive ventilatory support after contracting

Hospital patientspositive PCR

N =

Non-vaccinatedpatientsN = 8

Immunosuppressed patientsN = 4

Non-immunosuppresN = 4

Patients with hospital-acquired A(H1N1) infection

N = 10

Figure 1. Vaccination status of patien

the infection. The patients who acquired A(H1N1) infectionoutside critical care areas also required respiratory supportescalation, either in a critical care area or respiratory ward.

Only two (20%) of the patients who contracted HA-A(H1N1)had received the A(H1N1) vaccination. The majority of theother patients would have been eligible for influenza vacci-nation due to age or concurrent medical conditions. Unfortu-nately the information was not available to assess whetherthey had been offered vaccination prior to hospital admission.Following HA-A(H1N1) diagnosis, all the patients receiveda course of the neuraminidase inhibitor, oseltamivir.

Two of the patients died while in hospital and both patientshad serious underlying medical conditions (Table I). The othereight patients were all discharged from hospital. The length ofhospital stay varied from 12 to 84 days (median: 67).

Discussion

Hospitals are crowded places in which a reservoir of infec-tion and a vulnerable cohort of patients coexist. This studysuggests that significant transmission of A(H1N1) infectionoccurs in a tertiary hospital setting and that affected patientshave a high mortality (20%). Patient groups that appearvulnerable include those on critical care units, the immuno-compromised and those with a protracted hospital stay. Evenwith strict infection control measures, hospital transmission ofA(H1N1) will never be totally preventable and it is thereforeessential to consider alternative methods to reduce nosocomialA(H1N1) infection.

An in-hospital vaccination programme for all patientsadmitted during an influenza pandemic warrants further eval-uation. It is not only potentially in the patients’ best interests,but also could be resource-sparing by decreasing critical carerequirements and preventing prolonged hospital admissions.A(H1N1) antibody production takes two weeks which is clearlya limitation.3 However, in our study 70% of patients developed

with confirmed for H1N1

86

sed patients

Vaccinated patientsN = 2

Immunosuppressed patientN = 1

Patients admitted to hospital with A(H1N1) infection

N = 76

ts with influenza A subtype H1N1.

T. Veenith et al. / Journal of Hospital Infection 81 (2012) 202e205 205

A(H1N1) infection �7 days after hospital admission, suggestingthat in-hospital vaccination could be effective for somepatients. Vaccination might also help to reduce the risk ofvulnerable patients being readmitted to hospital withcommunity-acquired A(H1N1).

The safety of the vaccination programme is well estab-lished, with more than 42.5 million doses of H1N1 vaccinesadministered across Europe (data from Medicines and Health-care Products Regulatory Agency up to March 2010). Concernsexist regarding vaccination in the immunocompromised hostbut studies of children undergoing immunomodulatory therapydemonstrate that the vaccine is well tolerated.4 In addition,solid organ transplant patients appear to tolerate vaccinationwell despite initial concerns that the activation of non-specificcellular immunity might trigger organ rejection.5 Smallervaccination responses may occur, but it has been demonstratedthat the immunocompromised population can still achievesufficient antibody titres and a second influenza vaccine dosemay be given to ensure an adequate response.6 These safetyand efficacy data suggest that implementing a vaccinationprogramme in all high-risk patients on admission to hospitalshould be considered. Serological testing is unfortunatelyinaccurate as there is an absence of cross-reactivity betweeninfluenza strains and interpretation of results is challengingparticularly in the immunocompromised population.7,8 Aserological testing programme would therefore not be of usewhen deciding which patients should receive a second vaccinedose.

Healthcare workers are a potential source of A(H1N1)nosocomial infection. Research indicates that healthcareworkers often continue working during influenza infections,especially if symptoms are mild, and they risk transmitting thevirus to their patients.9 Data from the Department of Healthindicate that only 30% of frontline healthcare workers at CUHNHS Trust received the seasonal influenza vaccine in winter2010/11. Mandatory vaccination programmes have been themost effective means of increasing vaccination rates inhealthcare workers but the UK has chosen so far not to adoptthis approach.10

Limitations of this study include being performed in a singlecentre with a small population sample and that the impact onthe duration of hospital admission could not be assessed.Restricting the incubation period to five days or more may alsohave missed some cases of HA-A(H1N1). This study shouldprompt more research into prevention of transmission invulnerable patients. Visiting restrictions and staff vaccinationmay reduce in-hospital transmission. Further data are neededto assess the effectiveness of in-hospital vaccination againstA(H1N1) and the use of additional doses of vaccine in vulner-able patients.

In conclusion, HA-A(H1N1) infection is a common entityaccounting for more than 10% of all inpatient cases of A(H1N1)

influenza. Care should be taken to identify the ‘at-risk’ pop-ulation and further studies are required to define the potentialrole and effectiveness of vaccination in preventing suchinfection.

Acknowledgements

We thank Mrs Bushen and Dr E.F. Wallin for help with dataacquisition.

Conflict of interest statementNone declared.

Funding sourcesDr T. Veenith is supported by National Institute of AcademicAnaesthesia on a Clinical Research Training Fellowship, andRaymond and Beverly Sackler studentship.

References

1. Miller RR, Markewitz BA, Rolfs RT, et al. Clinical findings anddemographic factors associated with ICU admission in Utah due tonovel 2009 influenza A(H1N1) infection. Chest 2010;137:752e758.

2. Simonds AK, Hanak A, Chatwin M, et al. Evaluation of dropletdispersion during non-invasive ventilation, oxygen therapy, nebu-liser treatment and chest physiotherapy in clinical practice:implications for management of pandemic influenza and otherairborne infections. Health Technol Assessmnt 2010;14:131e172.

3. Girard M, Tam J, Assossou O, Kieny M. The 2009 A (H1N1) influenzavirus pandemic: a review. Vaccine 2010;28:4895e4902.

4. Esposito S, Cecinati V, Russo FG, Principi N. Influenza vaccinationin children with cancer receiving chemotherapy. Hum Vaccin2009;5:430e432.

5. Torii Y, Kimura H, Ochi N, et al. Immunogenicity of inactivated2009 H1N1 influenza vaccine in pediatric liver transplant recipi-ents. Vaccine 2011;29:4187e4189.

6. Pollyea DA, Brown JMY, Horning SJ. Utility of influenza vaccinationfor oncology patients. J Clin Oncol 2010;28:2481e2490.

7. Kunisaki KM, Janoff EN. Influenza in immunosuppressed pop-ulations: a review of infection frequency, morbidity, mortality,and vaccine responses. Lancet Infect Dis 2009;9:493e504.

8. McVernon J, Laurie K, Barr I, Kelso A, Skeljo M, Nolan T. Absenceof cross-reactive antibodies to influenza A (H1N1) 2009 before andafter vaccination with 2009 Southern Hemisphere seasonal triva-lent influenza vaccine in children aged 6 monthse9 years:a prospective study. Influenza Other Respir Viruses 2011;5:7e11.

9. Elder AG, O’Donnell B, McCruden EA, Symington IS, Carman WF.Incidence and recall of influenza in a cohort of Glasgow healthcareworkers during the 1993e4 epidemic: results of serum testing andquestionnaire. BMJ 1996;313:1241e1242.

10. Babcock HM, Gemeinhart N, Jones M, Dunagan WC, Woeltje KF.Mandatory influenza vaccination of health care workers: trans-lating policy to practice. Clin Infect Dis 2010;50:459e464.