Kōrero: Epidemics

Whārangi 5. New epidemics, 1970s to early 21st century

Ngā whakaahua me ngā rauemi katoa o tēnei kōrero

Despite improved health services and access to vaccines and antibiotics, New Zealand continued to experience severe outbreaks of disease in the late 20th and early 21st centuries.

Influenza

Deaths linked to influenza (the flu) and associated pneumonia have declined since the 1970s, when the virus caused, on average, about 1,000 deaths every year.

An annual influenza vaccine is offered in New Zealand to provide protection from the virus. It is adjusted each year to cover the strain or strains of the virus circulating at the time. Despite improved uptake of the vaccine, seasonal influenza epidemics continue to have an impact, especially on older people. Between 2000 and 2021, an average of 557 people died from influenza or pneumonia each year. Of these, 68% were aged 85 or older.

The 2009 influenza A (H1N1 – known as swine flu) pandemic generated more than 3,000 cases and caused 20 deaths in New Zealand, far fewer than health officials had feared.

Meningococcal disease

An outbreak of meningococcal group A in Auckland in 1985–86 was controlled by mass immunisation. Meningococcal disease reached epidemic proportions in the 1990s and early 2000s.

A new group B epidemic started in 1991, when 78 cases were recorded, compared to an average of 51 per year (1.5 cases per 100,000 people) previously. A New Zealand-only strain of the disease soon caused a major outbreak.

The highest infection rates were among Māori and Pacific Island children aged under five. The upper North Island, particularly Northland, Auckland and Rotorua, was most affected. The epidemic peaked in 2001 with 650 cases (17.4 per 100,000 people); 252 deaths were attributed to meningococcal disease between 1991 and 2007.

Brain fever

Meningococcal disease is a bacterial disease. It causes meningitis (an inflammation of the protective membranes covering the brain and spinal cord) and septicaemia (blood poisoning). Severe infections can cause shock, coma and death within a few hours if not treated quickly with antibiotics. Meningococcal disease can have serious long-term effects on survivors, including deafness and epilepsy.

A new vaccine developed specifically for the New Zealand strain of meningococcal group B was introduced in 2004. More than 1.1 million children and young adults were immunised. This was one of New Zealand’s largest mass-immunisation campaigns and involved schools, primary health care providers and district health boards. It cost more than $200 million. Reported cases declined from 342 in 2004 to 105 (1.7 per 100,000 people) in 2007, by which time the epidemic was regarded as controlled.

In March 2023 the meningococcal group B vaccine was added to the national immunisation schedule for the first time, which made it free for all children under five, and for teenagers and young adults living in crowded situations such as university hostels. A catch-up programme was organised to vaccinate children who had missed out previously.

Measles

Although a measles vaccine was made available in 1969, low immunisation rates meant that New Zealand continued to experience regular outbreaks of the disease. Improved uptake of the vaccine after 1980 reduced the frequency of outbreaks but had little effect on total case numbers when an outbreak did occur.

New Zealand experienced two large measles epidemics in the 1990s. The first, in 1991, resulted in 10,000 reported cases, an additional 30,000 suspected cases, several hundred hospitalisations and seven deaths. In response to this epidemic, a second dose of the measles, mumps and rubella (MMR) vaccine was added to the immunisation schedule.

A second, smaller, epidemic in 1997 resulted in 2,169 cases, but no deaths. This epidemic had been predicted, and a mass immunisation campaign planned to prevent it. When the epidemic began three months before the scheduled start of the campaign, this was brought forward and helped to limit the spread of the disease.

Although New Zealand has continued to experience measles outbreaks, the World Health Organization (WHO) declared the country free of endemic (circulating constantly in the population) measles in 2017. Outbreaks still occur when measles arrives from overseas. The last major outbreak was in 2019–20, when 2,194 New Zealanders caught the disease.

COVID-19

COVID-19, a new strain of coronavirus named SARS-CoV-2, spread around the world in early 2020. The virus, which primarily affects the respiratory system, soon overwhelmed health systems worldwide, leading to large-scale loss of life. In a ‘last-resort’ measure, the WHO declared the outbreak a ‘public health emergency of international concern’ on 30 January 2020.

New Zealand reported its first case of COVID-19 in late February 2020. As the number of local cases grew, the government introduced various public health measures to control the spread of the virus, many of them unprecedented in New Zealand history.

The most significant was a nationwide stay-at-home order (‘lockdown’). All New Zealanders were told to limit their physical contact with others and to only leave their homes for ‘essential’ activities such as exercising, grocery shopping and medical appointments. Mass testing of those with symptoms, contact tracing of infected persons and mandatory quarantine for people entering the country were also introduced to combat the spread of the virus. Wearing face masks was strongly encouraged, and later made compulsory in some environments.

Variants of concern: From Alpha to Omicron

The SARS-CoV-2 virus was first identified in China and probably originated in animals. Over time genetic mutations produced new versions of the virus, some of which posed a greater risk to public health than others. The WHO called them variants of concern and used the Greek alphabet to give them names that were easy to say and remember. Starting with the Alpha variant, which emerged in Britain in late 2020, COVID-19 worked its way through the alphabet, with Delta and Omicron the dominant variants in New Zealand in late 2023.

The lockdown was highly effective in reducing transmission of the virus, and by June 2020 there were no active cases of COVID-19 in the community. Most restrictions on movement and activities were lifted until August, when a new outbreak occurred. As the virus evolved and developed new variants, further outbreaks resulted, leading to more lockdowns. The severity of each lockdown varied, depending on the location and the number of cases.

A vaccine first became available in February 2021, and immunisation eventually became the primary means of fighting the virus. Proof of vaccination was required to enter some public settings, and health and education sector workers were required to be vaccinated to keep their jobs. The vaccine roll-out was the largest and most expensive mass immunisation campaign in the country’s history, costing $1.4 billion. By December 2021, 90% of the population aged 12 and over had received two doses of the vaccine.

Some objected to aspects of the government’s response, especially to the closing of international borders, which made it difficult for New Zealanders to return from overseas, and to the introduction of vaccination requirements for some professions. Despite this, the community was largely co-operative with the rules put in place.

Māori were very aware of the impact the 1918 influenza epidemic had had on their communities. Iwi and hapū, marae and Māori health organisations played important roles in communicating information, hosted testing and vaccination events, and provided families in need with food parcels during lockdown. To limit the spread of the disease, some set up roadblocks to stop people entering isolated communities.

As the country shifted to living with the virus, COVID-19 protective measures gradually ended. By the time the last public health requirements were lifted in September 2022, New Zealand had recorded more than 1.7 million cases of COVID-19, and more than 2,000 deaths (0.04% of the population). At the global level, there had been more than 612 million confirmed cases and more than 6.5 million deaths (0.08%). New Zealand was one of the few countries to record fewer total deaths than expected over the first two years of the pandemic, thanks to lockdowns curtailing the spread of infections such as seasonal influenza.

The virus has become a major cause of hospitalisation and a leading cause of death, especially amongst older people, accounting for 6.3% of all deaths in 2022. Since the start of the pandemic, those aged 20 to 49 have made up almost 50% of cases, while 94% of those who have died have been aged 60 or older.

Me pēnei te tohu i te whārangi:

Geoff Rice, 'Epidemics - New epidemics, 1970s to early 21st century', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/mi/epidemics/page-5 (accessed 26 February 2024)

He kōrero nā Geoff Rice, i tāngia i te 5 May 2011, reviewed & revised 8 Feb 2024