1Department of Microbiology, Royal Hospital, Muscat, Oman; 2Department of Epidemiology, Ministry of Health, Muscat, Oman; 
3 Department of Infectious Diseases, Royal Hospital, Muscat, Oman; 4Central Public Health Laboratory, Ministry of Health, Muscat, 
Oman
*Corresponding Author email: jalila76.mohsin@gmail.com

SQU Med J, December 2010, Vol. 10, Iss. 3, pp. 326-334, Epub. 14th Nov 10 
Submitted 23rd June 10
Revision ReQ. 1st Aug 10, Revision recd. 17th Aug 10
Accepted 30th Aug 10

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 AH1N1

 AH1N1 131
2009 31 23



 %63 %34.4 24
 %83%89.3%99.3
 %22.9
%75.7%57.3
%64.5%70.8    %75
%95.4%60.6
%88.9%6.9 48
 AH1N1

 %9.6

 AH1N1

aBstract: Objectives: : The aim of this study was to describe the clinical characteristics, risk factors, laboratory 
investigations and outcome of hospitalised patients with positive Influenza A (H1N1) at the Royal Hospital in 
Oman.  Methods: We extracted data from the retrospective medical charts, radiological and laboratory findings 
of 131 patients who were confirmed as positive for Influenza A (H1N1) by real-time reverse-transcriptase-
polymerase-chain-reaction from 21 July to 23 December 2009. Results: The median age was 24 years with 34.4% 
in the paediatric age group. Most (63%) of hospitalised patients were female. Symptoms at presentation included 
mainly fever (93.9%) and respiratory symptoms (89.3%). 83% of the patients had at least one risk factor and 
pregnancy was the most common associated condition (22.9%). Most of the patients had reduced lymphocytic 
count (57.3%) and high levels of serum C-reactive protein, aspartate transaminase and lactate dehydrogenase 
(75.7%, 75% and 70.8% respectively). The majority of the patients (64.5%) had evidence of pneumonia and 
radiological findings constituted mainly bi-lateral infiltrates (60.6%). Antiviral therapy was administered to 95.4% 
of the patients who mostly received it 48 hours after disease onset. Death occurred in 6.9% of patients. Out 
of these, 88.9% required Intensive Care Unit (ICU) care and mechanical ventilation.  Conclusion: Influenza A 
(H1N1) infection mainly affected those of younger age and females. Associated medical conditions were common, 

CLINICAL & BASIC RESEARCHCLINICAL & BASIC RESEARCH

Hospitalised patients with Influenza A (H1N1) 
in the Royal Hospital, Oman 

Experience of a tertiary care hospital, July–December 2009
*Jalila Al-Lawati,1 Nada Al-Tamtami,1 Ahmed Al-Qasmi,2 Amina Al-Jardani,1 Saif Al-Abri,3  

Sulaiman Al Busaidy4



Jalila Al-Lawati, Nada Al-Tamimi, Ahmed Al-Qasmi, Amina Al-Jardani, Saif Al-Abri, and Sulaiman Al Busaidy

Clinical and Basic Research | 327

Advances in Knowledge
This study adds to the literature on the data on the epidemiological and clinical characteristics of the pandemic Influenza A (H1N1) 
especially in the Middle East region.
Application to Patient Care
Information on the clinical spectrum of illness and risk factors for severity among people who were hospitalised at a tertiary hospital in 
Oman will substantially influence the clinical management, infection control policies and future preparedness plans.

In Spring 2009, the United States Centers for Disease Control and Prevention (CDC) reported an occurrence of 2009 Influenza 
A (H1N1) in Mexico and California.1,2 It was 
subsequently reported in virtually all countries.3 
The World Health Organization (WHO) declared 
the "first" phase 6 global influenza pandemic of the 
century on 11 June 2009.4 As of 20 December 2009, 
more than 208 countries had reported laboratory 
confirmed cases of pandemic Influenza A (H1N1) 
2009, including at least 11,516 deaths.4

In Oman, as of 2 January 2010, the Ministry of 
Health (MOH) announced that the total number of 
confirmed Influenza A (H1N1) positive cases was 
7,040 with 31 deaths.5 The WHO update on the 20 
December 2009 stated that Oman had a declining 
trends of respiratory disease activity after a peak 
in November 2009.4 Weekly reports on pandemic 
Influenza A (H1N1) from Oman are available in 
the MOH website;5 however, descriptive data on 
hospitalised patients has not so far been published. 

This study describes the clinical characteristics, 
risk factors, laboratory investigations and outcome 
of hospitalised patients, including health care 
workers, with positive Influenza A (H1N1) between 
21st July 2009 and 23rd December 2009 at the Royal 
Hospital in Oman.

Methods
We retrospectively reviewed the medical charts, 
radiological and laboratory findings of patients who 
were confirmed as positive for Influenza A (H1N1) 
by real-time reverse-transcriptase-polymerase-
chain-reaction (RT-PCR). These patients were 
admitted to the Royal Hospital (a 625 bed tertiary 
health care hospital) in Muscat, the capital city of 

Oman, between 21 July and 23 December 2009. 
They were distributed among medicine, paediatric, 
surgery, obstetrics and gynaecology wards, and the 
adult, paediatric and neonatal critical care units.

The following data were collected: demographic 
information on age, sex, and nationality; month 
of onset of illness; community versus hospital 
acquisition of the illness; duration of onset of 
illness to hospital admission; clinical features; risk 
factors for complications from Influenza A (H1N1); 
specific therapy given; the need for intensive care 
unit admission and/or ventilation; total hospital 
stay, and outcome.

A suspected case was defined as either 1) acute 
febrile respiratory illness (fever >38oC) with onset 
within 7 days of close contact with a confirmed case 
of (H1N1) Influenza A virus, or 2) within 7 days of 
travel to countries where one or more confirmed 
case of (H1N1) Influenza A virus had been reported 
or 3) residence in a community where there were 
one or more confirmed cases of (H1N1) Influenza A 
virus. A confirmed case was defined by the positive 
result of RT-PCR, viral culture or four-fold rise 
in (H1N1) influenza A virus specific neutralising 
antibodies.6

Associated medical conditions or risk factors 
for complications from Influenza A (H1N1) were 
defined according to the CDC criteria.7  Patients ≥12 
years were categorised as adults and those <12 years 
as children. Obesity was included as a risk factor if 
mentioned in the patients’ medical chart. For time 
calculations, the day of admission was considered 
to be hospital day 0. Community acquired infection 
was defined as onset of illness in the community or 
<48 hours in the hospital, while hospital acquired 
infection was defined as the onset of illness ≥48 
hours in the hospital.

with pregnancy being interestingly the commonest risk factor. The infection caused severe illness that required ICU 
admission and led to death in 6.9% of patients.

Keywords: Influenza; A (H1N1); Pandemic; Oman



Hospitalised patients with Influenza A (H1N1) in Oman 
Experience of a tertiary care hospital, July–December 2009

328 | SQU Medical Journal, December 2010, Volume 10, Issue 3

Laboratory tests included the total white 
cell count with specific lymphocyte count, total 
bilirubin, aspartate transaminase (AST), lactate 
dehydrogenase (LDH), creatine kinase (CK), serum 
creatinine and C-reactive protein (CRP). The 
radiological tests included either a chest X-ray or 
computed tomography of the chest which might 
show unilateral, bilateral or lobar findings. Routine 
bacterial cultures of blood, sputum or urine were 
performed upon clinicians’ requests.

Data collection and recording was undertaken 
by two candidates in the study team. The study was 
approved by the Research Ethics Board of the Royal 
Hospital.

All tests and procedures were performed at the 
requests of the physicians in charge of the patients. 
Two nasopharyngeal and two throat swab specimens 
were collected from each patient at or during 
admission whenever suspected. RT-PCR (ABI® Real 
time PCR) testing was done in accordance with the 
published guidelines from the CDC.8

Data entry forms were designed in Epidata 
software with check files to control for any entry 
errors. The Statistical Package for the Social 

Sciences (SPSS) Version 12, (SPSS Inc., Chicago, 
IL, USA) was used for analysis. Frequencies for 
categorical variables and means and medians for 
continuous variables were obtained. 

Results
A total of 497 cases with suspected Influenza A 
(H1N1) infection were hospitalised between 21 
July and 23 December 2009. Out of these, 131 were 
confirmed to be positive and available for analysis. 

The characteristics and clinical features of 
patients are presented in Table 1. The median age of 
the patients was 24 years (range 29.2 days–78 years) 
with the paediatric group accounting for 34.4% of 
patients. Of the total hospitalised patients, 63% 
were females, and the majority was Omani (86.3%). 
The mean ± standard deviation (SD) duration from 
onset of illness to hospitalisation was 4.8 ± 4.63 days 
and the majority of cases were community acquired 
(93.1%). 

Table 1: Characteristics and clinical features of all 
patients (N = 131) with Influenza A (H1N1). Data are 
presented as No. (%) unless specified otherwise

Characteristic Value/No (%)

Gender
          Female
          Male

83 (63.4%)
48 (36.6%)

Nationality
          Omani
          Non-Omani

113 (86.3%)
18 (13.7%)

Age in years
          Mean ± SD
        Median (Range)
        Age <12 years

25.9 ± 21.1
24 (29.2 days – 78years)

45 (34.4)

Duration from onset of illness 
to hospitalisation in days
          Mean ± SD 4.8 ± 4.63

Acquisition
          Community
         Hospital

122 (93.1%)
9 (6.9%)

Symptoms
          Fever
        Respiratory
Gastointestinal tract
        Any
        Adults (≥12years) 
        Children (<12 years)

123 (93.9%)
117 (89.3%)

8 (6.1%)
3 (3.5%)

5 (11.1%)

Table 2: Associated medical conditions in all (N = 131) 
patients with confirmed Influenza A (H1N1) according 
to their age group. Data are presented as No. (%)

Medical 
condition

<12yr  
n = 45

≥12yr  
n = 86

All 
patients  
N =131

Asthma or other 
chronic lung 
disease

8 (17.8%) 4 (4.7%) 12 (9.2%)

Obesity 0 7 (8.1%) 7 (5.3%)

Smoking 0 5 (5.8%) 5 (3.85)

Diabetes (type 
1 or 2)

0 20 (23.3%) 20 (15.3%)

Central nervous 
system disorders

2 (4.4%) 10 (11.6%) 12 (9.2%)

Cardiovascular/
peripheral
vascular disease

7 (15.6%) 13 (15.1%) 20 (15.3%)

Gastrointestinal 
disease

5 (11.1%) 3 (3.5%) 8 (6.1%)

Chronic renal 
failure

3 (6.7%) 8 (9.3%) 11 (8.4%)

Auto-immune 
disease

0 4 (4.7%) 4 (3.1%)

Immune 
suppression

5 (11.1%) 11 (12.8%) 16 (12.2%)

Malignancy 5 (11.1%) 1 (1.2%) 6 (4.6%)

Sickle cell 
disease

3 (6.7%) 2 (2.3%) 5 (3.8%)

Pregnancy    0 30 (34.9%) 30 (22.9%)



Jalila Al-Lawati, Nada Al-Tamimi, Ahmed Al-Qasmi, Amina Al-Jardani, Saif Al-Abri, and Sulaiman Al Busaidy

Clinical and Basic Research | 329

Symptoms at presentation mainly included 
fever (93.9%) and respiratory symptoms (89.3%). 
Diarrhoea or vomiting was found in 6.1%, including 
11.1 % of children and 3.5% of adults.

Table 2 shows the risk factors for complications 
with Influenza A (H1N1). Overall, 109 patients 
(83.2%) had at least one risk factor. Pregnancy was 
the most common condition (n = 30, 22.9%). Out 
of these 30 patients, none was in the first trimester, 
two were in the second trimester, 25 in the third 
trimester and three in the first 2 weeks postpartum. 
Six out of the 30 patients with pregnancy had 
additional co-morbidities including gestational 
diabetes mellitus, cardiovascular disease, bronchial 

asthma and immunosuppression. Around 15% of 
patients were diabetic and also had cardiovascular 
disease and 9.2% of patients had asthma or another 
chronic lung disease and also had a central nervous 
system (CNS) disorder. Asthma or other chronic 
lung diseases were more common in children 
(17.8%) and CNS disorders were more common 
in adults (11.6%). Interestingly, obesity, diabetes, 
smoking and auto-immune diseases were not 
found as risk factors in children. Malignancy and 
sickle cell disease were considerably higher in the 
paediatric age group.

Table 3 illustrates the diagnostic findings. All 
patients were tested for full blood count. The 
majority had lymphopaenia 75 (57.3%) while 32 
(24.4%) had leucocytosis. Serum levels of CRP,  
AST and LDH were noticeably high (75.7%, 75%  
and 70.8% respectively) in the proportion of 
patients who were tested. Of the 110 patients 
who underwent chest radiography, 71 (64.5%) 
had evidence of pneumonia of which 60.6% had 
bilateral infiltrates. Only 9 of the 104 patients had 
positive blood cultures. Five of these 9 patients had 
community onset bacteraemias (less than 48 hours 
post admission); one was due to Streptococcus 
pneumoniae pneumonia, three had urosepsis due to 
Gram negative organisms and one had Salmonella 
species meningitis (a post road traffic accident 
patient with skull injury). Four patients had hospital 
onset bacteraemias (more than 48 hours post 
admission). Organisms were hospital acquired 
Gram negative bacteria like multidrug resistant 
Acinetobacter baumannii (one case) and the other 
(two cases) resistant Gram negative bacteria and 
Candida albicans (one case).  

Of the 131 patients, 125 (95.4%) received antiviral 
therapy (oseltamivir). None received zanamivir or 
a combination antiviral therapy. Among patients 
who received antiviral therapy, 29.8% received it 
within 48 hours after onset of illness. A total of 
121 (92.3%) patients received antibiotic therapy, 
and corticosteroids were given for 39 patients 
(30%) mainly as intravenous administration. The 
indications of corticosteroids administration were 
mainly for underlying diseases (asthma, systemic 
lupus erythematosus (SLE), post renal transplant, 
etc). Others received it in the intensive care unit 
(ICU) for indications like septic shock and adult 
respiratory distress syndrome (ARDS).

The median hospital stay was 6 days (range 1-70 

Table 3: Results of diagnostic tests in all patients  
(N = 131) with confirmed Influenza A (H1N1)

Diagnostic test Abnormal 
result/ finding 
No/ total* (%) 

Cut off limit

Leucocytosis 32 (24.4%) >11.5x109/L 
(adults) 
>15.1x109/L 
(children)

Leucopaenia 11 (8.4%) <3.6x109/L 
(adults) 
<4.9x109/L 
(children)

Lymphopaenia 75 (57.3%) <1x109/L 
(adults) 
<4x109/L 
(children)

Total bilirubin 27/72 (37.5%) 3–17 µmol/L

AST 3/4 (75%) 10–45 IU/L

LDH 17/24 (70.8%) 95–190 IU/L

CK 7/16 (43.7%) 25–270 IU

Serum creatinine 24/113 (21.2%) 35–70 µmol/L 
in <15 yr  

45–100 in >15 
yr males 

45–90 in >15 
yr females

CRP 53/70 (75.7%) <5 mg/L

Chest radiography:

          Any 71/110 (64.5%) N/A

          Lobar 12/71 (16.9%)

          Uni-lateral 16/71 (22.5%)

          Bi-lateral 43/71 (60.6%)

*This represents the number of patients with a positive laboratory/
radiology finding divided by the number of patients who underwent 
that test.
Legend: AST = aspartate transaminase; LDH = lactate dehydrogenase; 
CK = creatine kinase; CRP = C-reactive protein; N/A = not applicable



Hospitalised patients with Influenza A (H1N1) in Oman 
Experience of a tertiary care hospital, July–December 2009

330 | SQU Medical Journal, December 2010, Volume 10, Issue 3

days) [Table 4]. Of 131 patients, 112 (85.5%) were 
discharged. The number of patients who required 
intensive care was 18 (13.7%) including 5 pregnant 
patients, while the number of patients who required 
mechanical ventilation was 14 (10.7%) including 3 
pregnant patients. The mean ± SD of duration of 
intensive care and that of ventilation were 9.2 ± 5.5 
days and 9.9 ± 5.9 days respectively.

Death occurred in 9 out of 131 patients (6.9%). 
Out of the 9 patients who died, 8 (88.9%) required 
ICU care and mechanical ventilation. The median 
age was 50 (range 24–78) years with the mean ± 
SD of the time from onset of illness to death being 
22.6 ± 12.5 days. There was no sex predilection. All 
of them (100%) had at least one associated medical 
condition. Pregnancy was not a risk factor, but one 
of the adult female patients was in the first week 
postpartum with no known medical risk factors. 
Eight out of the nine patients (88.9%) received 
oseltamivir more than 48 hours after the onset of 
illness.

Patients who were admitted to an ICU or died 
when compared to patients who were not admitted 
to an ICU and survived were older in age (median 
age 29 years, range 153.3 days – 78 years) and mostly 
female (73.7%) [Table 5]. They were less likely to have 
had received oseltamivir within 48 hours (15.8%),  
but were more likely to have received antibiotics 

(100%) and corticosteroids (68.4%). Pregnancy was 
found in (26.3%) and pneumonia on radiography 
was found in 89.5% compared to 59.3% in the group 
of survivors not admitted to the ICU. 

Discussion
We have described a cohort of 131 patients 
with confirmed Influenza A (H1N1) who were 
hospitalised at the Royal Hospital, Oman, between 
21 July and 23 December 2009. This is the largest 
series of hospitalised patients with Influenza A 
(H1N1) reported to date in Oman. The infection 

Table 4: Clinical outcome in all patients (N = 131) with 
confirmed Influenza A (H1N1). Data are presented as 
No. (%) unless specified otherwise.

Characteristic Value/No (%)

Total hospital stay in days
     Median (range) 6 (1-70 days)

ICU admissions 18 (13.7%)

Mechanical ventilation 14 (10.7%)

ICU Duration- days
     Mean ± SD 9.2 ± 5.5

Mechanical ventilation duration- days
     Mean (± SD) 9.9 (± 5.9)

Death outcome 9 (6.9%)

     ICU admissions 8 (88.9%)

     Mechanical ventilation 8 (88.9%)

     Age in years: median (range) 50 (24–78)

Duration from onset to death in    
days: 
     Mean ± SD      22.6 ± 12.5

Legend: SD = standard deviation

Table 5: Characteristics of patients with confirmed 
Influenza A (H1N1) who were admitted to an Intensive 
Care Unit (ICU) or died, and those not admitted to an 
ICU and survived. Data are presented as No. (%) unless 
specified otherwise.

Characteristic Admitted to 
ICU or died 

(n = 19)

Not admitted 
to ICU& 
survived  
(n = 112)

Age in years
Median (range)

29 
(153.3 days – 

78 years)

24
(29.2 days –70 

years)

Gender
     Female
     Male

14 (73.7%)
5 (26.3%)

69 (61.6%)
43 (38.4%)

Antiviral treatment
≤48 hours after                                                     
onset of illness

3 (15.8%) 36 (32.1%)

Antibiotic treatment 19 (100%) 102 (91.1%)

Corticosteroid 
treatment

13 (68.4%) 26 (23.2%)

Associated medical 
conditions
      Any
      Pregnancy

16 (84.2%)
5 (26.3%)

92 (82.1%)
25 (22.3%)

Pneumonia 
diagnosed by 
radiography* 

17/19 (89.5%) 54/91 (59.3%)

Organ dysfunction
      Elevated serum
      creatinine*
      Elevated AST* 
      Elevated total
      bilirubin*
      Elevated CK*

8/8 (100%)

1/1(100%)
9/18 (50%)

5/7 (71.4%)

16/94 (17.0%)

2/3 (66.7%)
18/54 (33.3%)

2/9 (22.2%)

*This represents the number of patients with a positive laboratory/ 
radiology finding divided by the number of patients who underwent 
that test.
Legend: AST = aspartate transaminase; CK = creatine kinase;  
CRP = c-reactive protein



Jalila Al-Lawati, Nada Al-Tamimi, Ahmed Al-Qasmi, Amina Al-Jardani, Saif Al-Abri, and Sulaiman Al Busaidy

Clinical and Basic Research | 331

affected mainly those of younger age and females. 
Associated medical conditions were common in this 
cohort with pregnancy found to be the commonest 
risk factor; however, 16.8% of the patients were free 
of any associated medical conditions. The infection 
caused severe illness that required ICU admission 
in 13.7% and death in 6.9% of the patients. Antiviral 
therapy was administered to most patients; however, 
it was commenced more than 48 hours after onset 
of the disease in the majority of cases. 

The observation of female susceptibility to 
develop Influenza A (H1N1) in this cohort is 
striking. This tendency, in general, has not been 
observed in other influenza case series except in two 
reports from Canada and Chile.9,10 The explanation 
behind this observation could be partly because of 
the relatively high proportion of pregnant women 
in this case series and that our hospital is the only 
tertiary hospital across Oman that serves for referral 
cases of obstetrics and gynaecology.

The distribution of cases in this cohort by age 
is characterised by the predominance of infection 
in the younger age group. This was similar to the 
findings observed worldwide10,11 including the 
first report of the present epidemic12 and previous 
influenza pandemics.13 Possible explanations for 
this observation include the greater susceptibility of 
young people to the virus on the basis of serological 
studies,14,15 and the fact that younger patients 
are more likely to be tested as they are more 
symptomatic than older ones.16

In this cohort, the patients experienced 
symptoms related to Influenza A (H1N1) infection 
over a mean duration of 4.8 days. This time period 
was comparable to other case series.9,17 Fever was the 
most frequent symptom that was observed in our 
patients (93.9%). It was the most common presenting 
symptom reported in most case series18,19 except one 
report in China17 where fever was less common. The 
incidence of diarrhoea or vomiting has occasionally 
been reported in children and in less than 5% of 
adults during peak periods of seasonal influenza.16 
This rate is similar to our results which showed 6% 
of patients with gastrointestinal symptoms.

The prevalence of associated medical conditions 
in our patients was high (83.2%). Published and 
unpublished data from the CDC showed that 
44 to 84% of hospitalised adults with seasonal 
influenza had an underlying condition.20,21 This high 
prevalence was also reported in other Influenza 

A (H1N1) series.22,23 Pregnancy was interestingly 
the commonest (22.9%) risk factor in our patients. 
Pregnancy as a risk factor has been noticed in 
previous influenza pandemics24-26 with a high 
disease-specific mortality;24 however, the prevalence 
in pregnancy in our study was higher than those 
reported by others.22,24 Most of our patients (84%) 
were infected in their third trimester which is  
similar to the findings in a large series in California 
which found that 95% of pregnant and postpartum 
women were infected in the second or third 
trimester.27 

Diabetes mellitus (type 1 or 2) and cardiovascular 
disease were found in 15.3% of our cases, while 
asthma or other chronic lung diseases and central 
nervous system disorder occurred in 9.2%. These 
rates were much lower than those reported in the 
US and Canadian Influenza A (H1N1) series.9,23 

The most consistent laboratory characteristics 
were lymphopaenia and leucocytosis. Lymphopaenia 
was reported in patients with Influenza A (H1N1) 
from Canada, China and Mexico.9,17 Most of our 
patients also had increased serum CRP, AST 
and LDH levels. Nine patients in our cohort had 
bacterial co-infection mostly caused by Gram 
negative bacteria. The low number of positive blood 
cultures in our series could be due to the fact that 
patients were mostly admitted as referrals from 
other hospitals and so would probably have been 
started empirically on antibiotics for pneumonia. 
This would have decreased the yield of positive 
blood cultures when they reached our hospital. 
The possible explanation for most of the cases of 
community onset bacteraemia being due to Gram 
negative organisms is that they mainly presented 
with infections (urosepsis) caused usually by Gram 
negative organisms and that most of them had 
risk factors for such infections (pregnancy, renal 
impairment, post skull fracture). The risk factors 
in hospital acquired bacteraemias due to Gram  
negative organisms were long hospital stay (more 
than a week), the presence of long lines and 
mechanical ventilation. During the 1918 pandemic, 
a large number of deaths were associated with 
bacterial infection.28 Other Influenza A (H1N1) 
series also reported bacterial co-infections;22 

however, the impact of concurrent bacterial 
infection on the severity of illness in our patients 
was difficult to assess especially because many 
patients received antibiotics before hospitalisation. 



Hospitalised patients with Influenza A (H1N1) in Oman 
Experience of a tertiary care hospital, July–December 2009

332 | SQU Medical Journal, December 2010, Volume 10, Issue 3

A significant proportion of our patients had 
radiological evidence of pneumonia with the 
majority having bilateral infiltrates on their chest 
radiography. The relationship of radiological 
findings with the cause of pneumonia is not yet 
established. Therefore, patients who are hospitalised 
with suspected influenza and lung infiltrates should 
be considered for treatment with both antibiotics 
and antiviral drugs.29

According to the CDC and WHO guidelines on 
the pharmacological management of the influenza 
virus, hospitalised patients and outpatients who 
are at high risk of complication should, if possible, 
receive oseltamivir or zanamivir as soon as  
symptoms develop.30,31 Although the evidence 
supporting such a recommendation is low, it has  
been shown that administration of oseltamivir  
within 48 hours of the onset of symptoms 
can reduce the duration of viral shedding as 
measured by real-time RT-PCR assay.17 Moreover, 
observational studies suggest that a reduction in 
mortality in hospitalised patients with influenza 
treated with oseltamivir can be achieved even when 
such therapy is initiated more than 48 hours after 
the onset of illness.22

A total of 30% of patients in our study received 
corticosteroids; however, steroids were given both 
to patients with an underlying disease (post renal 
transplant, systemic lupus erythematosus, chronic 
obstructive pulmonary disease, asthma, etc.) and to 
those who were critically ill in the ICU. Although 
the WHO recommendations state that steroids 
should be avoided in (H1N1) Influenza A, unless 
indicated for other reasons, the use of low dose 
steroids has been anecdotally accepted for such 
patients. Moreover, most of our patients in the ICU 
received it for indications like severe sepsis, septic 
shock or acute respiratory distress syndrome which 
could justify its use.

In our study, the patients who died or were 
admitted to the ICU were less likely to have 
received oseltamivir within 48 hours as compared 
to those who survived and were not admitted to the 
ICU (15.3% versus 32.1%). This might support the 
beneficial effect of early antiviral therapy. Moreover, 
although pregnancy was found to be the main 
risk factor in our series, pregnant patients were 
disproportionately admitted to ICU or died.

Death occurred in 6.9% of our patients. Out 
of these, 88.9% required ICU care and mechanical 

ventilation. All patients who died had at least one 
underlying medical condition. Eight out of these 
nine patients (88.9%) received oseltamivir more 
than 48 hours after the onset of illness. Delayed 
administration of antiviral therapy and the presence 
of underlying medical conditions could be seen as 
the causes that contributed to the mortality in our 
series. There is compelling evidence from the post 
mortem studies done on deaths in the 1918-1919 
influenza pandemic that bacterial pneumonia had 
a predominant role in mortality;28 however, most 
patients in our series had received antibiotics and 
all of those who were admitted to the ICU or died 
eventually did receive antibiotics.

The protective effect of H1N1 vaccine against 
H1N1 infection and related morbidity and  
mortality could not be assessed in our study. This 
was because the H1N1 vaccine did not reach the 
country until the last week of October 2009 and was 
only launched in the first week of November 2009. 
Our data collection was over by end of December 
2009 by which time the number of vaccinated 
individuals is assumed to have been low.

Our study has some limitations. The study 
included mainly hospitalised patients in one  
hospital and did not represent patients in the 
community or those with less severe illness that 
required admission to a secondary health care 
facility. Also, our study followed up the patients 
during the study period only which might have 
resulted in underestimation of the actual mortality 
rate. Finally, this study was retrospective and some 
data were missing. For example, it was not possible 
to get the weight and height for many patients to 
calculate the BMI and also it was not possible to 
segregate the respiratory symptoms into cough, 
dyspnoea, etc.

Conclusion
Influenza A (H1N1) infection in our setting 
affected mainly those of younger age and females. 
Associated medical conditions were common 
and pregnancy was interestingly found to be the 
commonest risk factor. The infection caused severe 
illness that required ICU admission and death 
in 6.9% of patients. Clinicians should consider 
influenza, including H1N1 infection, in their 
differential diagnosis for patients presenting with 
fever with respiratory or gastrointestinal symptoms. 



Jalila Al-Lawati, Nada Al-Tamimi, Ahmed Al-Qasmi, Amina Al-Jardani, Saif Al-Abri, and Sulaiman Al Busaidy

Clinical and Basic Research | 333

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c o n f l i c t o f i n t e r e s t
The authors reported no conflict of interest.

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