Viral infections | Pokenga huaketo

Viruses can cause infections (pokenga huaketo). While a healthy immune system can fight off most viral infections, some viruses cause serious disease. You can avoid getting some viral infections with regular hand-washing and vaccinations.

On this page, you can find the following information:

Key points

  1. Common viral infections include colds, flu, COVID-19, chickenpox, measles, Rubella (German measles), mumps, most cases of tonsillitis, bronchiolitis, hepatitis A and hepatitis B.
  2. Viruses spread easily from person to person, so it’s important to stay away from other people when you are infectious, as well as to wash your hands often and cover your coughs and sneezes.
  3. Antibiotics only kill bacterial infections – they are useless against viral infections. Misusing antibiotics to treat viral infections can cause antibiotic resistance.
  4. Vaccination can protect against some viruses, including the flu, COVID-19, measles, mumps, Rubella, hepatitis A and hepatitis B.
  5. Avoid catching viruses by washing your hands often, avoiding close contact with people who are unwell and supporting your immune system by living a healthy lifestyle. 

Image: 123rf

What is a viral infection?

A viral infection is caused by exposure to a virus. Viruses cause infections by invading their hosts' normal cells and using these cells to multiply and produce other viruses like themselves. 

How can I catch a viral infection?

Viruses spread easily from person to person through coughing and sneezing, contact with infected vomit or faeces (poo), exposure to bodily fluids in sex or sharing needles.

How is a viral infection treated?

Babies, older adults and people with a weakened immune system should see their doctor if they get a viral infection.

However, most people can rely on their immune system to fight off the majority of viral infections. Therefore, treatment for most viral infections aims to ease symptoms while you wait to recover. This can include:

  • resting at home
  • sipping water for hydration
  • drinking lemon and honey drinks for coughs and colds
  • taking paracetamol or ibuprofen to relieve pain and fever.

If needed, antiviral medicines can be used for HIV/AIDS and cold sores.

Video that talks about viral infections, their causes, diagnosis, prevention, and treatment

(Merck Manuals, US, 2020)

Do antibiotics help viral infections?

Antibiotics are useless in the treatment of viruses, as antibiotics only kill bacteria. Using antibiotics for viral infections can cause antibiotic resistance. Antibiotic overuse makes bacteria change so they are resistant to antibiotics – the antibiotics can’t kill them anymore. The more often antibiotics are used, the more chances bacteria have to become resistant.

Antibiotics need to be saved to treat severe bacterial infections.

How do I protect myself against viral infections?

You can stay vaccinated against viruses that cause some infections, such as the flu, COVID-19, measles, Rubella (German measles), mumps, hepatitis A and hepatitis B. Vaccination or previous infection means that when you encounter the virus again, you are likely to have fewer symptoms and a faster recovery, or you may not get sick at all. 

However, some viruses, such as those that cause the common cold, can change from one person to the next. Vaccination for these kinds of viruses is difficult because the viruses have already changed by the time vaccines are developed.

To avoid catching a virus:

  • Wash your hands often, especially after using the toilet, after handling pets and animals, and before preparing or eating food.
  • Avoid close contact with people who have a cold or the flu or another virus.
  • Don’t share household items (like cups and towels) with someone who has a virus.
  • Support your immune system by eating a healthy diet, getting plenty of rest, exercising regularly and living in a warm, dry home.
  • Avoid alcohol, smoking and drugs as these can weaken your immune system.
  • Use condoms and don’t share needles.

How do I prevent the spread of my viral infection?

Viruses spread easily from person to person. So that you don’t infect other people, take the following steps when you have a viral infection:

  • Stay away from work, school or childcare until your symptoms improve.
  • Cover your nose and mouth when you cough or sneeze.
  • Wash your hands often with warm water and soap.
  • Practice safe sex and don’t share needles.

Learn more

The following links provide further information about viral infections. Be aware that websites from other countries may have information that differs from New Zealand recommendations.

Viral infections MedLine Plus, US
Your family and antibiotics – what you need to know Pharmac, NZ
Antibiotic awareness Ministry of Health, NZ


  1. Infections – bacterial and viral Better Health, Australia, 2014
  2. Differences between bacterial and viral infection HealthDirect, Australia, 2018

Information for healthcare providers

Debate – do you prescribe antibiotics for respiratory tract infections? An everyday conundrum in general practice BPAC, NZ, 2015
Everything you need to know about the flu The Immunisation Advisory Centre, NZ, 2022
Respiratory tract infections (self-limiting) – reducing antibiotic prescribing BPAC, NZ, 2015
Cold season – managing without antibiotics BPAC, NZ, 2018

See also Health Navigator Clinicians pages for the relevant viral infection. 

Credits: Health Navigator Editorial Team. Reviewed By: Dr Janine Bycroft, GP Auckland Last reviewed: 21 May 2022