Opinion – Esper Kallás: Isolation of patients with the omicron

Several of the concepts that had been consolidating for Sars-CoV-2 were challenged with the arrival of the new variant.

With less aggressiveness, but still capable of causing serious disease, especially in unvaccinated people, the Ômicron surprised by its transmissibility. The numbers place him as a candidate for one of the most transmissible infectious agents we know of.

Among various concerns, many were faced with the question of what period of isolation was necessary. Or even if isolation is appropriate, for an agent that spreads so easily.

Although we know that the majority of the population will be infected, it is always prudent to take measures to reduce transmission. Efforts are, at the very least, to reduce the speed of dissemination and, above all, to protect the most vulnerable.

Is there a way to establish an isolation time that works for everyone, that is, 100% capable of preventing transmission? As with all biological phenomena, the answer is no.

Extreme examples subvert general rules. We will have some individuals who, even infected, may not transmit. There are also others that, with the defense system very weakened, can eliminate viruses for weeks or months.

Any period adopted will have flaws in both directions, whether it is allowing someone to transmit the infection after the recommended time, or imposing isolation time beyond what is necessary for some.

The mass transmission of the omicron forced a revision of these deadlines. With a tremendous number of people infected in a very short period, there was an impacting loss in the workforce, especially in essential functions. On pain of services collapsing, greater isolation flexibility was proposed.

One of the parameters that weighed in this evaluation was to observe how long, after the onset of symptoms, there was virus in the respiratory secretion with the ability to multiply in the laboratory. There are already data, with the omicron variant, in experiments carried out with a few dozen infected people in Japan. The results showed a scenario very similar to that of other variants. Ten days was the period in which the virus remained viable in the respiratory secretions, guiding the recommendations of the WHO and, until recently, the Ministry of Health.

Another reference came from the observation of transmission clusters, that is, secondary cases that occur from a confirmed case. The period of greatest transmission occurred in the five days after the onset of symptoms. This analysis served as the basis for the proposed isolation review in the United States.

In a middle ground, England and France have now adopted isolation for seven days after the onset of symptoms, using the test for the detection of antigens with a negative result as an additional safeguard.

Brazil follows this intermediate path, reducing isolation to seven days if symptoms disappear in that period. Tests to confirm? The scarcity of access in Brazil, unfortunately, does not allow its adoption in the practice of public policy. self test? Maybe it’s too late to help with the omicron wave.

Reinforcing what has already been seen, all these measures have imperfections and need to be considered according to the various contexts. Is it worth being more flexible to reinstate professionals in critical positions, such as health and safety? Is longer isolation worth it for those who live with people who are very vulnerable to developing serious illness? Certainly.

Applying such judgment is difficult but necessary in decision making.