The Interim Pre-Pandemic Planning Guidance published by the Center for Disease Control and Prevention (CDC) on February, 2007, is a community strategy for pandemic influenza mitigation in the United States. This document provides interim planning guidance including several measures other than vaccination and drug treatment that might be useful during an influenza pandemic to reduce its harm.

According with CDC, communities, individuals, families, employers, schools, and other organizations will be asked to plan for the use of these interventions to help limit the spread of a pandemic, prevent disease and death, lessen the impact on the economy, and keep society functioning.

The guide states that we must be prepared to face the first wave of the next pandemic without vaccine and potentially without sufficient quantities of influenza antiviral medications. At the same time, evidence to determine the best strategies for protecting people during a pandemic is very limited, because retrospective data from past influenza pandemics cannot reflect the modern society.

Isolation (may occur in the home or healthcare setting) and treatment (as appropriate) with influenza antiviral medications of all persons with confirmed or probable pandemic influenza is the number one instrument that the guide suggests.

Additionally, it is important to take actions regarding voluntary home quarantine of members of households with confirmed or probable influenza case(s) and consideration of combining this intervention with the prophylactic use of antiviral medications, providing sufficient quantities of effective medications exist and that a feasible means of distributing them is in place.

Dismissal of students from school (including public and private schools as well as colleges and universities) and school-based activities and closure of childcare programs, coupled with protecting children and teenagers through social distancing in the community to achieve reductions of out-of-school social contacts and community mixing is also mentioned in the guide.

Furthermore, the use of social distancing measures to reduce contact between adults in the community and workplace, including, for example, cancellation of large public gatherings and alteration of workplace environments and schedules to decrease social density is included as a mandatory process.

Finally, it emphasizes that if susceptible individuals are present in large numbers, disease spread may continue. Immunity to infection with a pandemic strain can only occur after natural infection or immunization with an effective vaccine. It is recommended for planning purposes that communities be prepared to maintain interventions for up to 12 weeks.

The validity of R0 as the basic reproductive number regarding a virus transmission

Lockdown is placing pressure on the global economy. We already face a serious recession. This pressure has led some world leaders to call for an easing of lockdown measures, even though R0 is not low enough in some areas yet.

The basic reproductive number, R0, is the average number of new infections that a typical infectious person will produce during her or his infection in a fully susceptible population in the absence of interventions. The estimated mean R0 for COVID-19 is around 3.28, with a median of 2.79.

According with the Interim Pre-Pandemic Planning Guidance published by the Center for Disease Control and Prevention (CDC) on February, 2007, the R0 number is not an intrinsic property of the infectious agent but is rather an epidemic characteristic of the agent acting within a specific host within a given milieu. For any given duration of infection and contact structure, R0 provides a measure of the transmissibility of an infectious agent.

Hence, alterations in the pathogen, the host, or the contact networks can result in changes in R0 and thus in the shape of the epidemic curve. Generally speaking, as R0 increases, epidemics have a sharper rise in the case curve, a higher peak illness rate (clinical attack rate), a shorter duration, and a higher percentage of the population infected before the effects of herd immunity begin to exert an influence.

To sum up, R0 is just a number, and it cannot rule decisions regarding human life. Also, studies identified experimental conditions for which the theoretical R0 predictions based on various hypotheses differ greatly, which would assist their discrimination and conclusive validation against future empirical studies. Furthermore, some of the mathematically derived estimates fall within the range produced the statistical and stochastic estimates, thus it is impossible to take policies regarding just a mathematical hypothesis, and not on true conditions and qualitative data.