Reacción a "Reaction to the announcement that Spain will reduce quarantine and isolation to seven days"

Right now we have two debates with very different implications for pandemic control.

On the one hand, there is the debate on reducing the quarantine period (i.e. the period in which a close contact must avoid contact with other people because he or she may be developing the disease). This reduction is motivated by the fact that some data point to a reduction of the incubation period with omicron. That is, the time it takes from the time you have close contact until you develop symptoms or have a positive PCR. If that period is shorter, quarantines could be shorter. The impact of reducing quarantine time is minor as, at least in Spain, vaccinated people have not been quarantined for a few months. Therefore, changes in quarantine time would have an impact especially on families with young unvaccinated children.

On the other hand, reducing the isolation period (the period that a person with symptoms can be contagious) may have further implications. We know that the first few days after the onset of symptoms are the most contagious. But there is no safe cut-off point after which a person will not excrete virus with 100% certainty. In people who are 5 to 7 days after testing positive, and who are completely asymptomatic, the chances of them infecting others are low. However, they are never zero and it is a continuum: the longer the time, the less likely they are to transmit.