It’s the 7th wave that is supposed to be the big one if you are at sea, or surfing. Let’s hope its not that way with COVID-19. Three waves appear to be more than enough for most countries, and by the seventh wave everyone will be extremely jaded with lockdown procedures. It is quite interesting to compare countries in the midst of their third wave on the basis of whether they have, or have not, had major vaccination campaigns.

I have only provided graphs for a few countries that display the most obvious trends. What it looks like is that a third wave has little effect on the number of deaths if a significant proportion of your population has been vaccinated. This is certainly what one would hope! It has also seemed, based on media reports, that most countries have vaccinated their most vulnerable first, with the elderly and people with illnesses likely to make them prone to becoming very sick with COVID-19, being at the top of the queue. This means the first part of the vaccination process will have the biggest effect on reducing numbers of deaths. Extra complexities in the deaths vs vaccination picture include that people require full vaccination (2 doses with all vaccines except Janssen) to protect against the delta variant, which is rapidly becoming the most prevalent COVID-19 strain, and numbers of deaths will likely drop even where some people are very sick, as long as hospitals and other medical resources are not overwhelmed (i.e. even if insufficient numbers of people are vaccinated to prevent virus spread, the effect of COVID-19 on the health system can still be massively reduced).

In the picture above showing the proportion of populations vaccinated against COVID-19, I have included New Zealand and Australia. New Zealand has full vaccination levels similar to Russia and Australia substantially lower. Seeing the New Zealand vaccination level makes it obvious why we really don’t want COVID-19 coming into the country at present. Our vaccination levels are not likely to be anywhere near enough to prevent there being a COVID infection wave that results in lots of deaths. Moreover, Australia has more people than New Zealand who will be highly susceptible to the delta variant. They are a risky country to have a travel bubble with, until New Zealand achieves higher rates of vaccination itself.

So what rates of vaccination are we aiming for? This has been an ongoing question, which was recently updated in the media. New modelling shows that 97 per cent of the New Zealand population needs to be vaccinated to achieve herd immunity in the face of new COVID-19 variants. Herd immunity is where sufficient people in a population cannot transmit disease, therefore person-to-person spread is very unlikely, and infections do not spread widely. This modeling is based on use of the Pfizer vaccine, the only one New Zealand is currently using, which in one of the most effective vaccines available, given that it prevents illness in 95% of people. A requirement for 97% full vaccination to achieve herd immunity is not good news. In the days of the good old alpha variant, the estimates were that we needed to vaccinate 60-70% of the population to reach herd immunity. The higher levels of infectivity that have been achieved by the delta variant mean this number has been revised heavily upwards.

Unfortunately, fully vaccinating over 90% of the population isn’t proving easy around the world. As far as I can find in the data, Gibraltar (population 33,000) has managed an impressive 115% vaccination rate, but the next country down the list is Cayman Islands (population 70,000) at 68%. Israel, a country that got off with a hiss and a roar in the vaccination race, is at 60% fully vaccinated and 5% partially. Canada features in the picture above as highly vaccinated, but only half of the 68% who have received vaccinations are fully vaccinated i.e. they won’t be protected against the delta variant. Mongolia is doing a lot better at 53% fully vaccinated (they got vaccines from both China and Russia).

Vaccinating 97% of the population anywhere is also downright impossible until vaccines are approved for children. At present Pfizer is only approved in New Zealand for children 12 and older, which means the 15% of the population who are under 12 cannot be vaccinated i.e. full vaccination of all those eligible would only achieve 85% vaccination rates.

The conclusion has to be that achieving herd immunity against COVID-19 in New Zealand is highly unlikely. It is already highly unlikely, and becoming ever more unlikely as all the countries who don’t have access to vaccines and good healthcare systems are reinfected, as each new wave/variant sweeps through. Every mass infection event is another opportunity for ever more infectious variants, and potentially more lethal variants, to arise. There is no doubt that delta is more infectious. It may also be more lethal – a Scottish study found 85% more people were hospitalised if they caught the delta variant, as compared with other variants. However, the time lag between infections and deaths means that there is not enough evidence yet available for definitive conclusions on delta’s lethality.

The best news out of the Te Pūnaha Matatini modeling has to be the effect of vaccination on reducing fatalities, as I mentioned above. If you vaccinate everyone over 65 (and no-one else) you reduce modeled deaths from 40,000 to 15,000 over two years, if the New Zealand border is opened and COVID-19 can move freely through the community. At 60% vaccination levels, which seems quite possible, there will be about 7,000 deaths over the 2 years, 3,500 a year. Let’s put this into the influenza perspective, around 500 people a year were dying of flu before we closed our borders. So COVID-19 might kill seven times the number of people each year who were dying of flu, that does seem like quite a lot.

In fact, 3,500 deaths each year would put COVID into the category of third highest killer of New Zealanders, after cancer and heart disease.

2022 will be an election year. I somehow doubt the government is going to like the idea of media headlines saying that opening the borders will mean COVID-19 killing 3,500 people a year, following on from 26 COVID-caused deaths in the last year and a half. Does that mean that our opportunities for overseas travel are going to remain limited for quite some time to come?