Effectiveness of cocoon strategy vaccination on prevention of influenza-like illness in young infants

Figures & data

Figure 1. Sample selection algorithm.

Table 1. Definition of illness.

Common Cold	Acute onset of runny nose, sneezing, nasal obstruction and/or cough, without fever No treatment was given
Influenza-Like Illness	Acute respiratory illness with a measured temperature of ≥ 38°C and cough, with onset within the past 10 days
Severe acute respiratory infections (SARI)	Acute respiratory infection with history of fever or measured fever of ≥ 38 C° and cough; with onset within the last 10 days and requires hospitalization

Table 2. Distribution of Socio-demographic data according to infants’ maternal or household vaccination status.

		Number of participants (%)
Category	Covariate	Infants whose mother is vaccinated but other members of the family are not 12.6% (n:26)	Infants whose parents and all people living with them are vaccinated against influenza 16% (n:33)	Infants with no members of the family vaccinated 68.9% (n:142)	p
Infants’ distribution according to mother’s education status	Primary school	2 (7.7)	6 (18.2)	44 (31.0)	.08
	High school	12 (46.2)	12 (36.4)	40 (28.2)
	Bachelor’s degree	12 (46.2)	15 (45.5)	58 (40.8)
Infants’ distribution according to father’s education status	Primary school	4 (15.4)	8 (24.2)	32 (22.5)	.83
	High school	8 (30.8)	12 (36.4)	46 (32.4)
	Bachelor’s degree	14 (53.8)	13 (39.4)	64 (45.1)
Infants’ distribution according to household size	≤4	16 (61.5)	31 (94)	108 (76.1)	.11
	4<	10 (38.5)	2 (6)	34 (23.9)
Second hand tobacco smoke	Yes	4 (15.4)	5 (15.1)	56 (39.4)	.03
	No	22 (84.6)	28 (84.9)	86 (60.6)
Exclusive breastfeeding	Yes	14 (53.8)	19 (57.6)	112 (78.9)	.23
	No	12 (46.2)	14 (42.4)	30 (21.1)

Table 3. Distribution of illness type according to infants’ maternal or household vaccination status.

Type of illness	Infants whose mother is vaccinated but other members of the family are not 12.6% (n:26)	Infants whose parents and all people living with them are vaccinated against influenza 16% (n:33)	Infants with no members of the family vaccinated 68.9% (n:142)	Total 100% (n:206)
None	38.5 (n:10)	48.5 (n:16)	30.9 (n:44)	35.9 (n:74)
Common cold	26.9 (n:7)	24.2 (n:8)	15.5 (n:22)	18.5 (n:38)
Influenza-like illness	11.5 (n:3)	18.2 (n:6)	14.2 (n:20)	14.1 (n:29)
Severe acute respiratory infection	23.1 (n:6)	9.1 (n:3)	39.4 (n:56)	31.5 (n:65)

Table 4. The effectiveness of the influenza vaccine according to vaccination status of infants’ household contacts.

Vaccination status of infants’ household contacts	The effectiveness of influenza vaccine
	For ILI	For SARI
Infants whose mother is vaccinated but other members of the family are not	35.3%	41.3%
Infants whose parents and all people living with them are vaccinated against influenza	48.9%	76.9%

ILI: Influenza-like illness, SARI: Severe acute respiratory infections.

Table 5. Risk estimates for ILI and SARI according to vaccination status of infants’ household contacts.

Vaccination status of infants household contacts	OR (95% Confidence Interval Lower Upper)		p value
	Risk Value For ILI	Risk Value SARI
Infants with no family members vaccinated (Group 1)	2.05 (1.15–3.56)	2.32 (1.17–4.59)	<.05
Infants whose mother is vaccinated but other members of the family are not (Group 2)	0.46 (0.19–1.18)	0.49 (0.17–1.21)	.12
Infants whose parents and all people living with them are vaccinated against influenza (Group 3)	0.36 (0.16–0.83)	0.17 (0.05–0.58)	<.05

ILI: Influenza-like illness, SARI: Severe acute respiratory infection.

Table 6. Factors associated with severe acute respiratory infections.

	Adjusted OR	%95 CI	p value
Vaccination status
None of the household contacts were vaccinated (Group 1)	Ref
Only mothers vaccinated (Group 2)	0.3	[0.11–1.21]	.09
All household contacts vaccinated (Group 3)	0.07	[0.01–0.56]	.01
Household size
≤4	Ref
>4	1.75	[1.24–2.48]	.01
Cigarette smoke exposure
No	Ref
Yes	2.2	[1.12–4.45]	.02
Exclusive breastfeeding
Yes	Ref
No	0.91	[0.44–1.12]	.93

CI, confidence interval; OR, odds ratio.