February 28 marked four years since Covid-19 was first reported in New Zealand. Many of us are probably surprised this virus is still causing a pandemic.
The World Health Organisation calls Covid-19 a continuing pandemic. As Scientific American put it recently, it "has been the elephant in every room — sometimes confronted and sometimes ignored but always present".
It was not meant to be like this. The 1918 influenza pandemic swept through New Zealand in eight weeks, killing 9000 people — almost 1% of the population. Then it was gone, returning as a new seasonal flu virus. In doing so, it defined how pandemics were expected to behave. This model was written into pandemic plans and collective thinking across the globe.
But Covid still circulates four years after New Zealand reported its first case, and more than two years after the Omicron variant arrived and became widespread. Constantly present, it also occurs in waves. Unexpectedly, the current fifth wave was larger than the fourth, suggesting we cannot rely on the assumption that Covid will get less severe over time.
These waves are driven by the interaction of the organism (Sars CoV-2 virus), the host (human characteristics such as immunity and behaviour), and environmental factors (such as indoor ventilation). Continuing viral evolution is a major contributor to the changing dynamic. The virus has demonstrated an ability for large, unpredictable evolutionary shifts that dramatically alter its genome and spike protein.
The result is an enhanced ability to evade prior immunity and infect more people. This jump was seen with the highly mutated BA.2.86 subvariant in mid-2023. Its offspring, JN.1, has acquired additional changes and is causing such a wave of new infections it could potentially be the next variant of concern, with its own Greek letter.
It is now driving epidemic increases across the globe, including in New Zealand. This dominance by a single subvariant takes us back to the first year of Omicron in 2022.
The pandemic continues to have a large health impact. It is a leading cause of serious illness and death, mainly in older populations and those with existing long-term health conditions. In 2023, it caused more than 12,000 hospitalisations and 1000 deaths in New Zealand.
But Covid-19 also has an important and largely unmeasured burden of disease as the cause of long Covid. A growing number of studies are describing an estimated incidence of long Covid of 5% to 15% of all infections.
For example, a recent large study of almost 200,000 Scottish adults reported that, after adjustment for factors that might confuse the results, long Covid prevalence following an infection was 6.6% at six months, 6.5% at 12 months, and 10.4% at 18 months.
These findings illustrate an important feature of long Covid: recovery can take two years or more, with symptoms that fluctuate over time.
New Zealand now needs a strong, integrated response to Covid-19 and other respiratory infections.
The major pandemic interventions have not changed: vaccination, public health and social measures to prevent infection, and antivirals for more vulnerable groups. The evidence has firmed up that long Covid risk is reduced by vaccination, but research is less certain for antivirals.
But growing pandemic complacency from political leaders and the public has changed things. Some of this apparent indifference can be put down to understandable fatigue with response measures. But it remains dangerous in the face of a continuing pandemic.
One way to keep a focus on prevention and control would be to include these measures in an integrated respiratory infectious disease strategy. This would combine Covid-19 control measures with those used to protect against influenza, respiratory syncytial virus (RSV), and other respiratory infections.
This integrated strategy would include vaccination, promoting testing and self-isolation when sick, and measures to reduce transmission in critical indoor environments. Such a programme would need to be supported with community engagement, education, surveillance and research.
Inequalities mean Māori, Pacific peoples, and those living in relative deprivation, are less vaccinated, less protected from infection, less tested and less likely to have antivirals. Consequently, they are more likely to be hospitalised and die from Covid-19. These inequities are not being systematically tracked and acted on.
As we enter the fifth pandemic year, we need a change in thinking about Covid-19. This infection has pathological features in common with the other severe coronaviruses (Sars and Mers).
It is wishful thinking to imagine it will suddenly transform into a common cold coronavirus.
In the face of this continuing pandemic threat, we need a response that is evidence-informed rather than evidence-ignored.
— Michael Baker is professor of public health at the University of Otago; Amanda Kvalsvig is an Otago Associate Prof of public health; Matire Harwood is an Assoc Prof of general practice at the University of Auckland.
