Introduction
A novel coronavirus emerged in China in late 2019. This new strain was
quickly identified, and genome sequencing established that this severe
acute respiratory syndrome coronavirus (SARS-CoV-2) was derived from
bats [1]. On March 11, 2020, the World Health Organization (WHO)
declared Coronavirus Disease 2019 (COVID-19) to be pandemic. As of July
18, 2020, SARS-CoV-2 has been responsible for more than 14000000 cases
and more than 600000 deaths worldwide [2].
Incubation period is the interval time elapsed between the moment a
person is infected until the onset of the disease. Knowledge of the
incubation period is essential for the case definition, management of
emerging threats, estimation of the duration follow-up for contact
tracing and secondary case detection and the establishment of public
health programs aimed at reducing local transmission [3]. Valid
measurement of the incubation period might be challenging in an
emergency context.
According to the WHO, SARS-CoV-2 incubation period ranging from 1 to 14
days has been reported [4]. Distribution of the incubation period
may vary between individuals as a result of certain determinants such as
host factors.
A paradox might be occurring; as the number of reported cases increases,
the quality of the parameter increases, with a reduction of the range or
the 95% confidence interval. However, the waiting time for obtaining
results from large sample size delays optimal decisions for the outbreak
investigation. Moreover, in case of a R0 of 2.5 to 3.0,
even outliers with a long incubation period may generate secondary
cases. Thus, measures of dispersion are as important as measures of
central tendency. Despite the lack of knowledge regarding transmission
during the incubation period, that interval conditions the amount of
contacts to investigate.
The situation is evolving daily and there is an urgent need to correctly
estimate the incubation period distribution of SARS-CoV-2 in order to
support effective outbreak investigations in various contexts such as
large or restricted geographic areas.
Therefore, the objective was to systematically review recent literature
of reported summary estimates of the distribution of incubation period
of SARS-CoV-2 with the aim of describing the distribution of incubation
period and identifying variations through a meta-analysis.