Early assessments of the spreading rate of COVID-19 were subject to significant uncertainty, as expected with limited data and difficulties in case ascertainment, but more reliable inferences can now be made. Here, we estimate from European data that COVID-19 cases are expected to double initially every three days, until social distancing interventions slow this growth, and that the impact of such measures is typically only seen nine days -i.e. three doubling times -after their implementation. We argue that such temporal patterns are more critical than precise estimates of the basic reproduction number for initiating interventions. This observation has particular implications for the low-and middle-income countries currently in the early stages of their local epidemics.
Enclosed societies (i.e. locations that are connected to wider community only by subgroups of their population and that are dominated by within society transmission) have the potential, upon establishment of a respiratory disease, to suffer a large proportion of the population within becoming infected. Care homes are particularly susceptible to COVID19 outbreaks and suffer high mortality due to vulnerable population within. Recent data on the number of new outbreak reports in care homes to Public Health England shows an initial increase then plateau perhaps associated with an SIS model dynamic. Without change in policy moving forward a high prevalence in such setting is predicted of around 75%. Action is needed to support staff in such settings.
In 1988 an epidemic of Q fever was detected in Leszno district. During 1973-1985 all 28,066 cattle tested for C. burnetii antibodies were found to be negative. The first seroconversions were found in cows which produced stillborn young. In the following years the number of seropositive cattle increased from 8.4% in 1987 to 21.6% in 1989. In 1988 all animal workers in the district were tested for C. burnetii antibodies. Of 4,264 persons tested, 1,451 (34%) were seropositive. A detailed study of workers and animals on one farm were performed. A herd of animals was found to be seropositive (32.1%), 68% of workers in direct contact with infected animals were seropositive and 29% of persons drinking raw milk. C. burnetii strains have been isolated from ticks, wild animals and birds hunted in close proximity of the farm. The dynamics of C. burnetii infection among animals and humans in this district and the fact that there is no importation of animal herds suggests that the possible route of introduction of Q fever in this area may be with imported semen or breeding bulls. The presence of C. burnetii in ticks and wild animals indicates the transfer of Q fever to the natural environment and its maintenance in this territory.
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