Dr Parmjeet Parmar, image supplied. Graphic via Getty
Dr Parmjeet Parmar, image supplied. Graphic via Getty

Dr Parmjeet Parmar: Herd immunity – a false hope for New Zealand.

Opinion 15/04/2021

OPINION: Believing that by achieving herd immunity with around 75% of New Zealanders getting vaccinated - that are willing to get vaccinated – will do the job for us, is a false hope.

It was nice to hear a Covid-19 vaccine related advertisement which basically says that people will be informed when it’s their turn. But what happens if people contacted decide not to get vaccinated?  It should not be a surprise that a significant number might say “no”.  Various surveys have shown around 1 in 4 New Zealanders are hesitant or will not get a Covid-19 vaccine.  

What makes it alarming is that despite knowing that there is a high vaccine hesitancy amongst New Zealanders, the government has done little of substance to convince people to reconsider their decision to not get vaccinated. 

The border is currently strictly controlled for the rest of the world except for to-be-soon opening trans-Tasman bubble, but it can’t stay like this forever. The vaccine is planned to be rolled out to the general public in July. This would raise hopes of wider quarantine-free travel later this year. 

But, standing in the way of this goal are those 1 in 4 New Zealanders that are unlikely to receive their Pfizer jab. It is widely believed that quarantine-free travel will be safe only once we have achieved herd immunity. But what does the concept of herd immunity actually mean for us?

For once, we can’t compare ourselves to our usual international competitors.  Australia, the UK and the US are in completely different positions that we can’t use to model our way forward. It will be a very bumpy road to achieving the level of immunity that will impart us the “Covid-19 immune nation” status. 

Believing that by achieving herd immunity with around 75% of New Zealanders getting vaccinated - that are willing to get vaccinated – will do the job for us, is a false hope. It is important that we are not lying to ourselves that somehow around 75% of people vaccinated will protect everyone from the virus.  It will reduce the chance of Covid-19 becoming an epidemic but it will still leave those 1 in 4 New Zealanders at risk.  

To start with, we do not have any community cases, so we are not looking for a decline in number of cases as other nations with thousands of positive cases each day desperately are by trying to reach the immunity threshold referred to as herd immunity.  With so far around 2,500 New Zealanders which is 0.05% of our population that has contracted the virus, we have at least 99.95% of our population that is not immune.  Out of this 99.95%, if only 75% are vaccinated, we will have around 1.3 million people that could not only be infected with Coronavirus but will also have high chances of developing the Covid-19 disease.

We have seen the impact of around 2,500 positive cases on us and it is beyond our imagination to imagine the possibility of around 1.3 million people developing Covid-19. 

This is close to Auckland’s population that will still be at risk of catching, spreading and suffering from the virus. That is a massive gap in achieving the goal that one imagines to achieve with herd immunity. 

One infected individual can infect all or some people that they come in contact with.  The research to fully establish any effect of vaccines on individuals getting infected and transmitting the virus is still underway. One thing that is established for sure so far is that the vaccines help with reducing the chances of anyone developing Covid-19 disease and dying.  

The WHO has already warned that global herd immunity is unlikely to be reached this year because of some poorer countries having to wait longer for vaccines.  

So, for us to open borders with around 75% of our population vaccinated and go quarantine-free would result in more community cases.  But on the other hand, keeping the borders closed or allow only quarantined entry is not a long-term option. 

This leaves the government with two options:

First, try to convert those against the jab into changing their mind and coming forward, or secondly, prepare the hospital systems to deal with escalation of cases. 

But we have had the recent news of hospitals announcing that they are not able to cope with the number of patients presenting themselves. This is despite there being no current cases of Covid-19 in the community. 

Now what could be a definite relief for hospitals and the health sector as a whole would be to get more New Zealanders saying “yes” when they are contacted to inform them of their turn to get vaccinated. We should stop talking about herd immunity and rather focus on getting lot more than already willing people vaccinated.

The concept of herd immunity has no meaning for our expectations. It will not give us the protection of negligible community cases that we are used to with closed borders.

Written by Dr Parmjeet Parmar, a former Families Commissioner and National Member of Parliament, has a PhD in Biological Sciences from the University of Auckland.