Uncover the Truth: Discovering if You're Still Contagious After an Illness - Doctor's Insights

The result:

As autumn arrives in the Northern Hemisphere, temperatures are dropping, causing a rise in cold-like symptoms among individuals. Some have received positive test results for Covid-19, influenza, or the respiratory syncytial virus (RSV). As we approach winter and witness the spread of viral infections, many individuals may question the duration of their contagiousness following infection and the length of time they should practice precautions and refrain from contact with others.

To provide guidance on these inquiries, I interviewed Dr. Leana Wen, our CNN Wellness medical expert. Dr. Wen is an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She has previously served as Baltimore's health commissioner.

CNN: Is there a simple method to determine if someone remains contagious following a viral infection?

Dr. Leana Wen: There isn't one. In the case of numerous viruses, a person who is infected can transmit it to others even before showing any symptoms.

Sick woman wiping her nose with tissue paper

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In addition, while there are tests available for detecting the virus, they are generally not used to confirm someone as virus-free after infection, except for Covid-19. The US Centers for Disease Control and Prevention states that individuals with improving symptoms and two consecutive negative home coronavirus tests, taken 48 hours apart, can end their isolation.

Furthermore, another complicating factor is that many individuals may experience persistent symptoms even after the infectious period has ended. For instance, a cough could persist for weeks or even months following a respiratory illness. These symptoms are a result of ongoing airway inflammation and do not indicate continued infection or pose a risk to others.

CNN: How long can an infected person transmit common viruses like coronavirus, influenza, RSV, or the common cold to others on average?

Wen: Let's discuss each of these viruses individually. As for the virus that causes Covid-19, SARS-CoV-2, it can be spread by individuals who are infected but do not show any common symptoms such as cough, fever, runny nose, or sore throat. It is also possible for an infected person who has not yet developed symptoms, someone who is presymptomatic, to be contagious.

Scientists estimate that the most contagious period for SARS-CoV-2 is 48 hours before symptoms develop and the first five days afterward. According to the CDC, individuals infected with Covid-19 should isolate for five days and then wear a high-quality, well-fitting mask around others for the following five days, unless they receive two consecutive negative test results, as previously mentioned.

Young woman suffering from cold

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Scientists have discovered the reason behind the increased incidence of colds and flu during the winter season. Asymptomatic transmission of influenza is believed to be less frequent. Although there is a possibility of spreading the flu to others before symptoms appear, the period of highest infectiousness is estimated to be approximately three to four days after the onset of illness. The Centers for Disease Control and Prevention (CDC) suggests that generally healthy adults can potentially infect others for up to five to seven days after falling ill, while individuals with compromised immune systems might have the ability to transmit the virus for an even longer duration.

RSV is highly contagious, with a longer period of contagiousness. It typically infects almost every child before the age of 2, and those infected can spread the virus for three to eight days after developing symptoms. However, transmission before symptoms occur is also possible. Infants and immunocompromised individuals may continue spreading the virus for up to four weeks after symptoms subside.

On the other hand, the common cold can be caused by over 200 different viruses. The length of contagiousness varies depending on the specific virus and the overall health of the infected person. Generally, there may be a pre-symptomatic period of contagion, and the peak infectiousness occurs within three to five days after symptoms appear. However, individuals may still be able to transmit the virus for up to two weeks after becoming infected.

CNN: Given the extended periods in which individuals can potentially transmit the infection, what measures should individuals with cold-like symptoms adhere to while attending school or workplace?

Wen: Schools and workplaces have acknowledged the impracticality of expecting individuals to remain home until their entire infectious period has passed. Even if policies were in place, requiring individuals to stay away from school or work until two or even four weeks after symptom resolution, viral transmission would still occur due to asymptomatic and presymptomatic transmission.

Asian woman with eyes closed wearing protective face mask commuting in the city and waiting for subway in platform

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Children typically experience around six episodes of viral respiratory infections per year, while adults generally have two to four. Implementing a policy such as this would result in significant absenteeism, which has considerable implications for children's learning and development, as well as its impact on workplaces and the economy.

To address this issue, many schools have adopted policies that strike a balance between keeping children in school and minimizing the spread of infections during periods of high contagion. For example, parents may be asked to keep their children at home if they have a fever, and the child should be fever-free for a minimum of 24 hours without the use of fever-reducing medication before returning to school. In certain cases, a doctor's note may be required if the child continues to exhibit noticeable symptoms, such as coughing.

If you are unsure about the protocols in your workplace, it is advisable to seek guidance from your human resources department. It is generally recommended to stay at home if you have a fever or if you begin experiencing new symptoms. If it is necessary for you to go back to work, make sure to wear a properly fitted, high-quality mask in public or shared areas in order to prevent spreading the infection to others.

CNN: How can individuals prevent infecting their household members?

Wen: This is tricky. Parents of young children know that they often get sick when their kids do because its so hard to avoid infection when you are in close contact.

Bandage after applying vaccine

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Reasons for administering the RSV vaccine to eligible individuals:

It is crucial to determine the individuals within a household who are more susceptible to experiencing severe consequences if they were to be infected by these viruses. If everyone in the family is generally in good health, many households may choose not to go to great lengths to isolate someone who exhibits cold-like symptoms. However, if there is an elderly person with underlying medical conditions, it is logical to separate the infected individual from them. These two individuals should refrain from dining together or being in the same room for a minimum of one week following the onset of symptoms.

Preventive methods can effectively help combat these challenging viral infections. Make it a habit to regularly wash your hands or use hand sanitizer. It's also important to keep your vaccinations up to date, which includes the Covid-19 vaccine, flu shot, and the new RSV vaccine for individuals aged 60 and above. These vaccines play a crucial role in reducing the risk of severe illness and decreasing the likelihood of getting infected by these specific viruses.

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