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Table 2 Seropositivity among different study groups at various time periods in the year 2009

From: Seroepidemiology of pandemic influenza A (H1N1) 2009 virus infections in Pune, India

Study groups

Month of 2009

No. sampled

HI titre ≥1:10

HI titre ≥1:40

   

No.

% (95% CI)

No.

% (95% CI)

Hospital staff

August

495

43

8.7 (6.2-11.2)

14

2.8 (1.4-4.3)

 

October

524

40

7.6 (5.4-9.9)

25

4.8 (3.0-6.5)

 

November

385

77

20.0 (16.0-23.9)

46

12.0 (8.7-15.1)

General practitioners

August

385

62

16.1 (12.4-19.8)

19

4.9 (2.8-7.0)

 

November

278

67

24.1 (19.1-29.1)

26

9.4 (5.9-12.8)

 

December

225

80

35.6 (29.3-41.8)

34

15.1 (10.4-19.8)

School staff

August

348

23

6.6 (3.9-9.2)

7

2.0 (0.5-3.5)

 

September

177

46

26.0 (19.5-32.5)

19

10.7 (6.2-15.3)

School children

September

2527

800

31.7 (29.8-33.5)

631

25.0 (23.3-26.7)

Railway commuters

September

225

27

12.0 (7.8-16.3)

13

5.8 (2.7-8.8)

Office staff

September

233

25

10.7 (6.8-14.7)

8

3.4 (1.0-5.8)

Slum-dwellers

September

651

67

10.3 (8.0-12.6)

23

3.5 (2.1-5.0)

General population

October

2520

242

9.6 (8.4-10.8)

151

6.0 (5.1-6.9)

PCR-confirmed cases

September- October

65

53

81.5 (72.1-91.0)

48

73.8 (63.2-84.5)

Household contacts

September- October

195

70

35.8 (29.2-42.6)

50

25.6 (19.5-31.8)

  1. CI = confidence interval, HI = haemagglutination-inhibition, PCR = polymerase chain reaction