Health and Safety

What we learnt from our Public Health Response to COVID

July, 2022

By: Paul Jarvie

Manager Employment Relations & Safety – EMA

What is Public Health?

The health of the general population, and in particular, efforts by the Government to improve the health outcomes of the population through regulation and other forms of support. Public health involves branches of medicine including hygiene, epidemiology and disease prevention.


Viruses are the most abundant organism on the planet. There are millions of viruses, although most are harmless and aid being healthy. For example, there are around 140,000 viruses living within the human gut. The world and humans need viruses. Some viruses are obviously welcome, while others can cause mild to severe and deadly consequences. There are 219 virus species that are known to be able to infect humans. Below are viruses that infect humans most frequently:

  • Common cold
  • Influenza (flu)
  • Herpes
  • Chickenpox
  • Mumps
  • Human papillomavirus (HPV)
  • Measles
  • Rubella

The deadliest viruses include Ebola, Marbug, Lassa, MERS-CoV (Middle East respiratory syndrome coronavirus), SARS (Severe Acute Respiratory Syndrome).

Key Virus Definitions

  • Epidemic – an unexpected increase in the number of disease cases in a specific geographical area.
  • Endemic – a disease outbreak is endemic when it is consistently present but limited to a particular region.
  • Pandemic – when a virus covers a wide area, affecting several countries and populations. The rate of spread is vastly larger for pandemics than endemics. Pandemics cut across international boundaries and are very contagious. COVID-19 became a pandemic.

Public Health Outcomes for a Virus

  • Control – reducing the number of new infections, the number of people currently infected, and the number of people who become sick or die from a disease in local settings.
  • Elimination – stopping disease transmission in a specific geographic area or country (but not worldwide).
  • Eradication – a permanent reduction to zero of the worldwide incidences of infection.
  • Extinction – no diseases are present worldwide.

Managing Risk

It is important to understand how the risk model works and how it worked through a COVID lens:

Risk Mitigation Factors

COVID Example – New Zealand

Avoiding risk by deciding not to start / continue the activity that gives rise to the risk

Closed borders, lockdowns, isolation, quarantines, stay at home, QR tracking

Accepting or increasing the risk to pursue an opportunity

Limited reopening of business, workplace bubbles, split work / rest times, home isolation

Removing the risk source

Personal hygiene, sanitising, separation, masks

Changing the likelihood of the risk

Separation, masks, reduce public gatherings, QR tracking

Changing the consequences of the risk


Sharing the risk with another party or parties (including contracts and risk financing)

Contracting others to be exposed to risk.

Retaining the risk through informed decision

Now under Orange business opening, encourage masks, separation, personal hygiene, encourage booster shots

COVID-19 and the Ministry of Health Response

When COVID-19 first hit New Zealand, it presented as a contagious disease with a reproductive factor of 2.5 (i.e., one infected person transfers the disease to 2.5 other people). The Ministry of Health decided to take a “public health” risk approach to mitigate the virus. This approach was initially to stamp out the virus using an elimination strategy, so isolation and lockdowns were the first choice. This approach limited exposure of individuals to other individuals thus minimising virus transmission. The reason for this option was to limit pressure on the health system, namely hospitals and GP’s.

Businesses, and the needs of business, were not really considered. As time progressed, the Government offered a range of grants and subsidies that both employees and employers could access. However, the health approach remained prominent.

Within the public health response was the call to follow some basic rules. These rules again managed exposure and therefore transmission. In general, the public health responses was / is both simple and effective at reducing the spread of the virus.

The response included:

  • Personal hygiene (e.g. sneezing into a tissue or your elbow)[1]
  • Mask wearing[2]
  • Washing hands[3]
  • Sanitising[4]
  • Social distancing[5]
  • Airconditioning/ open windows[6]
  • Vaccination[7]
  • Quarantine
  • Isolation

[1] This action limits the amount of air being expelled via the sneeze. Given a sneeze can generate speeds of up to 145Km/hr plus and produce 100,000 droplets the potential for any virus to travel beyond the sneezing person is huge. Some reports indicate that a virus from a sneeze could travel up to around 20 feet. Airconditioning and open windows (draughts) could also add further air travel distance. Virus material within water droplets caught in an elbow or tissue is therefore rendered unable to be airborne and thus not able to travel through the air.

[2] Masks serve two functions. Firstly, they trap virus material entering the mouth or nostril when inhaling. Inhaling while wearing a mask places a physical barrier to airborne material-viruses. The mask material is important as it must be able to trap/inhibit material of very small diameters. Viruses are incredibly small but modern mask materials are well able to cover these ranges. Secondly if a person has a virus, then when they exhale or cough/sneeze any contaminated air will be trapped within the breathing zone inside the mask, thus limiting free air movements.

[3] Incredibly, people touch their faces between 30-60 times per hour. If our hands, fingers and fingernails are dirty or contaminated with a virus then transfer is likely. Washing hands frequently with warm soapy water followed by a brisk drying action is often a good approach, especially after coughing and/or sneezing.

[4] Coupled with hand washing, sanitising kills and debrides the skin of the virus. Sanitising uses alcohol (75% plus) to kill the virus, which is very effective and can be practiced frequently throughout the day especially before and after touching other surfaces.  Sanitising high touch points is also very effective. The virus has been reported as being able to live on some surfaces for many hours under ideal conditions. An alcohol wipe will kill the virus that have settled on surfaces.

[5] This practice uses distance along with the use of masks to limit airborne transfer of viruses. Keeping at least 1 metre or 2 metres from others will disrupt virus transmission between individuals.

[6] Because the virus is so small and therefore very light, it is severely influenced by airflow. Airconditioning units, by design, move air around and pass air through high grade filters. These filters can trap the virus within the filter material and then be disposed of at filter replacement. Open windows, even by a small amount, will allow fresh air to be introduced into the room.

[7] The use of vaccines is fundamental to a public health response to fight viruses. Vaccines prepare the body defence systems to be able to react quickly to any virus that invade the body. They do not completely stop people getting the virus. Being vaccinated also speeds up the recovery time.

Outcomes of the NZ COVID response

A report from Otago Public Health Expert blog (Feb 2022) stated there were fewer reports of influenza-like illness symptoms, such as fever and cough in New Zealand’s population in the winters of 2020 and 2021. These findings build the case for some degree of ongoing public mask wearing and reinforce the co-benefits of COVID-19 control on other conditions (such as preventing influenza and community pneumonia).

Further, years of life lost was lower than expected in New Zealand, Taiwan, Norway, Iceland, Denmark and South Korea. For New Zealand, Taiwan, Iceland and South Korea, these findings for 2020 “could be attributed to the successful pandemic elimination policies of these countries, including evidence-based population health interventions”.


  • Public health measures are simple and effective.
  • The best messages are to “stay at home” and “get vaccinated”. Employers would be urged to continue with these and other public health controls.
  • This year, the winter flu may be worse as the population is more vulnerable. However, evidence shows the winter flu vaccine, masks, separation, good hygiene and sanitisation will help keep the virus at bay.
  • The Government’s health response was not a business / economic response. Isolation and lockdowns took precedence over economic considerations.
  • Virus mutations are both expected, and to some degree, welcome. Each new mutation while more contagious is also less severe. This means more people are likely to be infected, however, most will only suffer a mild head cold type illness (Omicron).
  • The Government and employers need to continue the narrative about the continued use of well proven public health interventions plus the need for vaccination.
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