Following a constant decrease in the attack rate of this disease in developed countries during the past decades, a marked increase in its incidence has been recently recognized worldwide [ 1, 2].
If the infectious dose is very low we expect more asymptomatic infectious individuals [42] that in turn will decrease the attack rate, decreasing the number of infectious individuals and thus of severe cases.
Nevertheless, quarantining each virus-negative contact in 1 room did not significantly decrease the attack rate of suspected cases among virus-negative contacts in comparison with quarantining 2 persons in 1 room.
Concomitantly, a decrease in MRSA attack rate from six to one new case per 1,000 patient-days was seen.
Improved infection control in the second phase may not be the primary reason for the decrease in the attack rate over time.
The efficacy of a conjugate pneumococcal vaccine to decrease the attack rate of AOM has been evaluated in a randomized controlled clinical trial on 4968 children.
It, however, gives a clue that the decrease in exposure may have played a relatively important role in the decreased attack rate in the second phase.
Definitive conclusions regarding vaccine efficacy beyond 24 months of age cannot be drawn from these results, but one could speculate that the relatively few RVGE-related hospitalisations and ED visits, or decreased relative attack rate in the third year of life was probably due to naturally acquired immunity [ 18].
Lastly, if fecal shedding of RV1 leads to horizontal transmission of vaccine virus and resultant immune response in unvaccinated contacts of vaccine recipients, as was shown in a clinical trial in the Dominican Republic, this might decrease the attack rates of disease in unvaccinated children and decrease estimates of RV1 effectiveness as measured through observational studies.
To implement an innovative training strategy to improve HH compliance and decrease MRSA attack rates in a large (36 beds) mixed adult ICU.
We find that targeted class closure affords strong mitigation effects: closing a class for a fixed period of time – equal to the sum of the average infectious and latent durations – whenever two infectious individuals are detected in that class decreases the attack rate by almost 70% and significantly decreases the probability of a severe outbreak.
