Flu Transmission: Risks and Prevention Tips

Influenza Transmission Issues

Hello, Doctor.
My mother (60 years old) contracted the flu last Tuesday (March 12).
Her symptoms included fever, runny nose, and sore throat.
As of today, March 22, she still has a cough with phlegm and a runny nose, but she no longer has a fever or other discomfort.
Just now, she coughed in my direction without wearing a mask, only lightly covering her mouth with her fist.
I was facing away from her, about 1.5 meters away, and I also wasn't wearing a mask.
I'm very worried about getting infected and would like to ask the doctor:
1.
How long is the contagious period for the flu? Does she still have the ability to transmit the virus? After 10 days, is she still shedding infectious flu virus, or is her cough now just due to phlegm without shedding infectious virus?
2.
What is the likelihood of me getting infected? I had the flu with her last November, so I should have some antibodies, right?
3.
Does taking zinc supplements help prevent the flu or a cold? I am currently taking them, but I'm unsure of their effectiveness.
Thank you, Doctor, for your hard work.

Niming, 20~29 year old female. Ask Date: 2024/03/22

Dr. Zheng Jueyi reply Otolaryngology

1.
The infectious period for influenza ranges from one day before the onset of symptoms to 3 to 7 days after symptoms appear, during which individuals may transmit the virus to others.
However, there are individual variations, so it is uncertain whether a person with only a productive cough is still shedding infectious virus.

2.
In individuals with normal immune function, infection is not guaranteed.

3.
Research has shown that taking zinc within 24 hours of the onset of cold symptoms can shorten the duration of the illness by 1 to 2 days, but this does not mean that zinc can prevent influenza or the common cold.

Reply Date: 2024/03/22

More Info

Understanding flu transmission is crucial, especially in the context of your mother's recent illness. Let's break down your questions regarding flu transmission, the duration of contagiousness, and preventive measures.

1. Duration of Contagiousness: The flu virus is typically contagious from about one day before symptoms appear until about five to seven days after becoming sick. In your mother's case, since she started showing symptoms on March 12 and it's now March 22, she is likely at the tail end of her contagious period. While she may still have a cough and some residual symptoms, the risk of her transmitting the virus decreases significantly after the fever subsides and other symptoms improve. By now, it is unlikely that she is shedding a significant amount of the virus, especially if she is no longer experiencing fever or severe symptoms.

2. Risk of Transmission: Given that you were approximately 1.5 meters away from her while she coughed and that she only lightly covered her mouth, there is a potential risk of transmission, but it is relatively low. The flu virus spreads primarily through respiratory droplets when an infected person coughs, sneezes, or talks. However, since you have previously been infected with the flu in November, you may have developed some level of immunity, which could further reduce your risk of contracting the virus again. While it's possible to get the flu more than once, especially if different strains are involved, your previous infection may provide some protection.

3. Zinc Supplements: Regarding the use of zinc supplements, there is some evidence suggesting that zinc may help reduce the duration and severity of cold symptoms, but its effectiveness in preventing the flu is less clear. Zinc is known to play a role in immune function, and while it may help bolster your immune response, it should not be relied upon as the sole preventive measure against the flu. A balanced diet, good hygiene practices, and vaccination are more effective strategies for flu prevention.

Additional Preventive Measures:
- Vaccination: The flu vaccine is the most effective way to prevent influenza and its complications. If you haven't received this year's flu vaccine, consider doing so, as it can provide protection against the most common strains circulating.

- Hygiene Practices: Regular handwashing with soap and water, or using hand sanitizer, can help reduce the risk of infection. Avoid touching your face, especially your eyes, nose, and mouth, as this can introduce viruses into your system.

- Avoid Close Contact: Try to maintain distance from individuals who are sick, and encourage your mother to cover her mouth and nose with a tissue or her elbow when coughing or sneezing.

- Healthy Lifestyle: Maintaining a healthy lifestyle, including a balanced diet, regular exercise, adequate sleep, and stress management, can enhance your immune system's ability to fight off infections.

In summary, while your mother's contagious period is likely nearing its end, it's wise to remain cautious. Continue practicing good hygiene, consider vaccination, and maintain a healthy lifestyle to bolster your immune defenses. If you have any further concerns or if symptoms develop, consulting a healthcare provider is always a good step.

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