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Common viruses - How long are they contagious?

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Last Updated: March 18, 2020, 14:05 IST

Common viruses - How long are they contagious?

Vaccination against many of the most dangerous viruses is available and recommended in India.

While some viral infections trigger no noticeable reactions in the human body, many can cause deadly diseases that can be fatal. Depending on the kind of virus and how healthy someone is, to begin with, an infection can take place. Viruses can infect every type of tissue in the body from the brain to the skin. Unlike bacterial infections, viral infections cannot be cured with commonly available antibiotics. In fact, in some cases, antibacterial medicines can even cause more harm due to the side effects of drugs interacting with the viral infection. Viruses are living organisms that need a host cell to grow and multiply. They cannot survive without it.

They cause several deadly diseases such as:


The common cold

Different types of influenza






Herpes and cold sores.



Ebola and Hanta fever

HIV, the virus that causes AIDS

Severe acute respiratory syndrome (SARS)

COVID-19 - better known as the Coronavirus

Dengue fever, Zika, and Epstein-Barr

Virus transmission

The only reason a virus exists is to grow and multiply, spreading far and wide to new cells and hosts. Yet because of the way a virus is built, there are limitations on how it can spread. Viruses can travel from pregnant mother to child during the pregnancy or delivery as well as from person to person via:

  • Insect bites or insects that carry them from person to person.

  • Coming into contact with body fluids like spit, mucus from sneezing and cough droplets that sometimes reach up to six feet away.

  • Touching an infected person

  • Sexual contact

  • Consuming contaminated water or food

Some viruses can stay alive on everyday objects like tables, doors, trains, buses and more for an extended period. If an infected person touches an item, the next person to touch the same thing can also get that virus. As the virus replicates in the body, it starts to affect the host, and after the incubation period is over, symptoms may begin showing up. Vaccination against many of the most dangerous viruses is available and recommended in India

Infectious period

The length of time you're contagious for after contracting a viral infection depends on the type of virus involved, and it usually starts by the person feeling unwell or noticing other symptoms like a rash, fever, runny nose, etc.

Read on to find out how long some of these common viruses can be infectious.

Common cold

The common cold starts being infectious from a few days before the symptoms actually show up and only stops after all symptoms are completely gone. Symptoms are usually at their worst during the first couple of days. This is when the person is most likely to spread the virus. Though, someone can pass on the cold from the time the symptoms appear until all of them are gone. Usually, this lasts for around two weeks.

Influenza (Flu)

The Flu lasts about a week. But the person is usually infectious from day one just before you show symptoms to about a week after you begin feeling unwell. Like the common cold, this virus can also be spread right until the symptoms disappear.

Vaccine - Available


How long bronchitis is infectious depends on what caused it. When the bronchitis is caused by the same virus that caused the common cold or Flu, you can expect to be contagious until you no longer have any of the cold or flu symptoms. In the case of acute bronchitis, symptoms such as a persistent cough may linger for several weeks even after the infection is gone. But, once the infection is gone, bronchitis is no longer contagious.

Vaccine - Available


Chickenpox is highly infectious 48 hours before the spots appear and stays like that until they have crusted over. This usually happens 5 - 7 days after they first appear.

Vaccine - Available


The chickenpox virus can lie dormant in spinal nerves for years after someone has had chickenpox as a child. Shingles are caused by the virus getting activated and causing a rash that wraps around the side of the torso. People who haven't had chickenpox before could catch the virus while the rash oozes fluid and develop chickenpox.

Vaccine - Available


Symptoms of measles appear around 1-2 weeks after you become infected. Infected people can spread the disease from four days before the rash starts until about four days after.

Measles is most infectious after the first symptoms (high fever, red eyes,  runny nose, watery eyes, swollen eyelids) show and before the rash develops. About four days in, a red-brown rash dots the body and doesn't fade until after about a week.

Vaccine - Available


This virus is just below and in front of your ears and makes your salivary glands swell. The infection is most communicable from a few days before your glands swell until a few days afterwards. Mumps is dangerous because it can lead to viral meningitis if the virus moves into the outer layer of the brain.

Vaccine - Available

Rubella (German measles)

When an infected person with rubella virus sneezes or coughs, the virus can be passed from person to person due to tiny drops of fluid that fly out from the nose and throat. People who have rubella are most contagious from seven days before to seven days after the rash appears. Infected people should quarantine themselves for  6 days after the rash first develops and avoid contact with pregnant women as much as possible.

Vaccine - Available

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    Having said that, it's essential to understand that the vast majority of human viral infections can be effectively fought by the body's immune system. The best way to help an infected person is to make sure they are adequately hydrated, get enough rest and are eating nutritious meals. Treatment for a viral infection can include everything from preventative vaccinations to antiviral antibiotics or combinations of virus-specific drugs. There is no cure for a virus, but vaccination can prevent them from spreading, and some antivirals can help slow down and manage them in some cases.

    This is a partnered post.

    first published:March 18, 2020, 14:05 IST
    last updated:March 18, 2020, 14:05 IST