Skip to main content
. Author manuscript; available in PMC: 2020 Dec 16.
Published in final edited form as: Vaccine. 2020 Nov 4;38(50):8040–8048. doi: 10.1016/j.vaccine.2020.09.076

Table 2.

Knowledge of herd immunity and estimates of local MMR vaccine coverage among the 493 participants who completed the survey.

n %
Aware of herd immunity a Yes 334 67.8
No 159 32.3
Missing 0
Estimate of herd immunity threshold for measles 95% ±5 percentage points (correct estimate) 201 40.8
Underestimated (<90%) 291 59.0
Missing 1 0.2
Estimate of MMR vaccine coverage in participant’s county of residence Correct coverage estimate (±5 percentage points) 156 31.6
Overestimate (>5 percentage points higher than actual) 135 27.4
Underestimate (<5 percentage points lower than actual) 198 40.2
Missing 4 0.8
Perceived that their own county was at risk of an outbreak b Yes 293 59.4
No 195 39.6
Missing 5 1.01
a

Participants were categorized as being “aware of herd immunity” if they chose “vaccinating enough people to protect even those who are not vaccinated”, the correct definition of herd immunity, when asked about the definition of the concept and not aware if they chose any other option.

b

Participants were categorized as those who “perceived that their own county was at risk of an outbreak” if their estimate of the MMR vaccine coverage in their county of residence was lower than their estimate of the herd immunity threshold for MMR. This is a construct of the two previous variables. Participants were informed during the survey about how their estimates compared with actual coverage levels and the actual herd immunity threshold.