Perhaps the greatest current pandemic risk to New Zealand arises from a growing complacency that we have suppressed Covid 19 and therefore have defeated the pandemic. At some stage in the future, we will open our borders and will seek to travel again. At that point, we will confront Covid in its various international genetic variants. There are three variants of concern identified at present: South Africa (B.1.351), UK (B.1.1.7) and Japan/Brazil (P.1). The catastrophic situation in India is likely to provide the time and the environment for more contagious deadly variants to evolve. Even before the re-engagement with the rest of the world occurs, it is predictable that at least some occasional mishaps will occur, despite our generally effective managed isolation and quarantine systems. Such mishaps, when combined with the arrival of one of the more deadly and contagious variants, could initiate a new cluster, or even launch a fresh pandemic wave.
These and other concerns have been highlighted in a recent authoritative report from the Lancet Covid 19 Commission Taskforce on Public Health. This report calls for a strategy of “maximum suppression” to deal with a situation where vaccines per se are not enough.
How can we achieve maximum suppression? The most important step will be to achieve a high level of vaccination. Vaccination will certainly minimise the impact, but this must be coupled, when required, with a rapid comprehensive re-adoption of familiar community health precautions, including hand washing, distancing and wearing of masks. The Lancet Commission has made recommendations calling for increased capacity in studies of vaccine effectiveness against new variants and the adoption of improved public health measures. It also proposes an improved range of interventions, including ventilation and tracing. Its main conclusion is that no single action is sufficient to prevent the spread of Covid.
At present, the evidence suggests that the Pfizer vaccine remains effective against variants. However, the South Africa variant seems to reduce the effectiveness of the AstraZeneca vaccine against mild to moderate illness.
Reluctance to accept vaccination or the avoidance of second jabs are major obstacles to achieving global immunity and so defeating the pandemic. The World Health Organisation (WHO) has reported that a vaccination threshold of 70 per cent is required before general immunity can be established. Gallup has recently surveyed the international level of public reluctance to accept vaccination. This survey reveals that only in Asia and Africa are vaccination acceptance levels above the 70 per cent immunity threshold. The anxieties regarding vaccinations are difficult to comprehend, given that 1.3 billion people have already satisfactorily received the Pfizer and related vaccines.
Covid will not be defeated until it is defeated everywhere, so the emergence of “vaccination nationalism” among some wealthy countries is of great concern. COVAX, the international organisation that is committed to equity of access to vaccination in poorer countries, has acknowledged that vaccine distribution at present is vastly uneven. It is extraordinary that human self-interest may yet represent the greatest barrier to defeating the pandemic.
Emeritus Professor Ralph Cooney