December 4, 2023

By Katia Hetter | CNN

It’s fall within the Northern Hemisphere, and the climate is getting cooler. Many individuals have cold-like signs, and a few could have examined constructive for Covid-19, influenza or the respiratory syncytial virus (RSV).

With winter on the best way and viral infections growing, lots of people could surprise how lengthy they are going to be contagious after an infection and the way lengthy they need to take precautions and keep away from contact with others.

How can somebody know if they’re nonetheless contagious? If that’s the case, what’s the common size of time they may transmit viruses such because the coronavirus, influenza, RSV or the frequent chilly to others? And what precautions ought to an contaminated particular person take at college, work and at house?

To information us by these questions, I spoke with our CNN Wellness medical knowledgeable, Dr. Leana Wen. Wen is an emergency doctor and professor of well being coverage and administration on the George Washington College Milken Institute Faculty of Public Well being. She beforehand served as Baltimore’s well being commissioner.

CNN: Is there a simple approach to inform if somebody remains to be contagious after having a viral an infection?

Dr. Leana Wen: Probably not. For a lot of viruses, an contaminated particular person is contagious even earlier than they begin exhibiting signs.

Additionally, whereas there are some exams that may let you know whether or not you’ve got the virus, they often aren’t used to clear somebody after an infection. The exception is Covid-19. In response to the US Facilities for Illness Management and Prevention, somebody whose signs are enhancing and who has had two adverse house coronavirus exams spaced 48 hours aside can finish isolation.

Another complicating issue right here is that many individuals could proceed to have lingering signs properly after their infectious interval ends. It’s frequent to have a cough, for instance, that might final for weeks and even months after a respiratory sickness. Such signs point out ongoing airway irritation however don’t mirror ongoing an infection or danger to others.

CNN: What’s the common size of time somebody might transmit the virus to others if they’re contaminated with frequent viruses just like the coronavirus, influenza, RSV or the frequent chilly?

Wen: Let’s undergo every of those. The virus that causes Covid-19, SARS-CoV-2, might be unfold by asymptomatic people who’re contaminated however don’t exhibit any of the frequent signs equivalent to cough, fever, runny nostril and sore throat. An contaminated one that has not but developed signs—somebody who’s presymptomatic—can also be contagious.

Scientists estimate that the interval of maximal contagiousness for SARS-CoV-2 is within the 48 hours previous to creating signs after which the primary 5 days after. The CDC recommends that an individual contaminated with Covid-19 ought to isolate for 5 days after which put on a high-quality, well-fitting masks when round folks for the subsequent 5 days, except they check adverse with two consecutive exams, as I discussed above.

Asymptomatic transmission of influenza might be much less frequent. Whereas it’s attainable that you could possibly unfold the flu to others earlier than you develop signs, the interval of maximal contagiousness is considered three to 4 days after the sickness begins. The CDC advises that in any other case wholesome adults might be able to infect others as much as 5 to seven days after changing into sick, and a few folks, like these with weakened immune techniques, would possibly be capable of infect others for a good longer time frame.

RSV has a doubtlessly longer interval of contagiousness. These contaminated with RSV, which is a quite common respiratory an infection believed to contaminate practically each youngster earlier than they flip 2, are often contagious for 3 to eight days after they develop signs, although presymptomatic transmission is feasible too. In response to the CDC, some infants and folks with immunocompromise might maintain spreading the virus for so long as 4 weeks after they cease having signs.

As for the frequent chilly, there are over 200 viruses that may trigger it. The interval of infectiousness relies on the virus and on the well being of the person contaminated, however usually follows an analogous sample to the opposite viruses mentioned. Briefly, there might be a time earlier than exhibiting signs that the particular person could also be contagious, and often the interval of maximal infectiousness is within the three to 5 days after signs start. Nonetheless, they are able to unfold the virus for so long as two weeks after an infection.

CNN: With such lengthy intervals of potential infectiousness, what precautions ought to folks with cold-like signs take at college and workplaces?

Wen: Colleges and workplaces have lengthy acknowledged that it’s unrealistic to ask that folks keep house till all the interval throughout which they might be infectious passes. Even when they’d insurance policies asking that folks keep out of college or work till, say, two and even 4 weeks after signs resolve, there’ll nonetheless be viral unfold due to asymptomatic and presymptomatic transmission.

Additionally, provided that youngsters undergo a mean of six bouts of viral respiratory infections a 12 months, and adults two to 4, this type of coverage would outcome lots of absenteeism, which has many results on youngsters’s studying and improvement, to not point out impacts on workplaces and the economic system.