Table 4.

Influenza vaccination studies examining transmission within households.

Reference (SIGN)	Design	Population	N	Mean age (range)* in years	Season	Outcome description	Outcome			Direction effect (−, −/+, +)
							Measure	Outcome	95% CI/ p-value
Antimicrobial use of household contacts of vaccinated children
Esposito (++) [17]	RCT	Parents	254	36.8/38.1	2000–2001	Antimicrobial prescriptions	VE	27%	.01	+
		Siblings	95	5.3/5.0	2000–2001	Antimicrobial prescriptions	VE	33%	.01	+
Hurwitz (+) [24]	RCT	Household contacts	29	0–4	1996–1997	Antimicrobial prescriptions	VE	NR		−/+
			59	5–17	1996–1997	Antimicrobial prescriptions	VE	88%	.02	+
			140	≥18	1996–1997	Antimicrobial prescriptions	VE	NR		−/+
Vaccination of household contacts and antimicrobial use in infants
Maltezou (++) [21]	Non-randomized	Mother–infant	530	30.5 (15–46)/ 30.9 (15–45)	2012–2013	Antimicrobial administration	Difference**	45.4%	.014	+
					2012–2013	Antimicrobial administration	OR***	0.472	0.911–0.245/.025	+
		Other household contacts	1291*	NR	2012–2013	Antimicrobial administration	NR		NS	−/+

* Overall, there were 1844 members in the 553 studied households, including 553 mothers, 525 fathers, 358 siblings, 323 grandparents, 73 other relatives, and 12 caregivers; ** Number of antimicrobial administrations (95% CI) in infants of vaccinated mothers: 22 (4.9–11.6) versus infants of unvaccinated mothers: 40 (10.8–19.5);*** The odds ratio is presented here has been calculated in conventional format as the risk in post-partum vaccinated mothers, rather than the original format which presented the risk in those unvaccinated; CI confidence interval; NR: not reported; NS: not significant; OR: odds ratio; RCT: randomized controlled trial; SIGN: Scottish Intercollegiate Guidelines Network; VE: vaccine effectiveness.