A small number of academics have been advocating in the New Zealand media of late for something they call Plan B as a basis for our ongoing response to Covid-19.

The main thrust of the argument of the people driving Plan B seems to be that we are overreacting to the Covid-19 pandemic. One of the group, Dr Simon Thornley, has even suggested we are using a sledge hammer to crush a flea in our response.

One of the basic tenets of the group's argument is that the Covid-19 situation is somehow no worse than a bad flu season for most people. There are many arguments against this but let's just focus on the practicality of their plan.

Essentially, they advocate that within New Zealand everyone should return to normal except those at risk, a group they propose would include those over 60 or who have diabetes, obesity, heart disease or some form of compromised immune system.

These people would somehow be sealed off from the rest of the population to protect them until a vaccine is found and the government would somehow support these people.

By my calculation that would mean trying to wall off about a quarter of the population and it is not clear how this would be achieved or maintained while everyone else got on with their lives.

This in itself creates a situation that amounts to medical apartheid and will create problems for society that could be nearly as damaging as those we have at the moment. It would have to go on for a very long time because there would undoubtedly be a surge in Covid-19 cases in the general population as a result.

The impact of the policies will also impact particularly on Maori and Pacific communities where the incidence of the at-risk conditions are highest and where older people are more likely to live with the family group.

While a plan will indeed need to be developed to protect the most at-risk elderly people, the Plan B approach is certainly no guarantee of protection for this group.

Plan B also makes the assumption that younger people won't suffer badly from Covid-19.

This is generally the case but for the record, the latest data from the US Centres for Disease Control and Protection shows that nearly a quarter of all deaths are actually in people under 65 so it is not just affecting the elderly.

What is more there is evidence emerging that those who recover from Covid-19 can have long-term damage to their health resulting from the disease.

The restrictions put in place in New Zealand to date are in response to a rapidly developing global epidemic and it was certainly better to be safe than sorry.

Our plan is a specific solution developed here in the knowledge that cases were much lower than elsewhere in the world and with the aim of getting the best outcome as quickly as possible.

These measures, combined with our geographic isolation, offer us the real possibility of us actually eliminating this virus from inside our country.

The "Plan B" people say this is not possible because testing is not widespread enough nor 100 per cent accurate. They are essentially arguing that the cat is out of the bag.

However, with intense testing and follow-up of emerging cases and clusters we can overcome the limitations of the tests and the month of lockdown should stop the vast bulk of opportunities for transmission.

I would argue that the rapidly falling numbers of both Covid-19 cases and the anecdotal evidence of less overall respiratory illness give us hope that eradication is a real possibility. Samoa has shown that if you are careful, you can keep a country Covid-19 free with good border control strategies - and we can do the same.

Plan B proponents argue that strong social restrictions will lead to a lack of respect for authority.

I fail to see how their plan would improve this situation as there would be a lot of resentment to their plan from those who remain segregated and it would be very easy for these people to break the "rules" imposed by their plan.

There would also be the ongoing cases of Covid-19 lurking with the social unease associated with that. In any case, lockdown under "Plan A" won't have to last as long as Plan B people suggest because there is already a lot of light at the end of the tunnel.

Everyone realises we can't keep the lockdown forever and we can see that the Government is already working on a plan to get a sensible level 3 plan in place.

We all hope this will deliver a solution that will allow us to get back to some semblance of "new normality" as quickly as possible.

Virtual eradication of Covid-19 from New Zealand and then using our isolation to protect us from the Covid-19 in the rest of the world by using proper quarantine measures would certainly allow more people to return to more normality more quickly.

Finally, I'd argue the full implications of Covid-19 are not yet known and we are all guessing to some extent but it's clear, whatever happens now, it will cause a lot of disruption for quite a while - so we need to do what is best for New Zealand.

In that regard, the analogy Dr Thornley has used is a bad one in general, as not only is Covid-19 not a flea, but rather, or at the very least, a serious infestation of fleas.

Anyone who has tried to catch fleas will know they are pretty nimble and that by the time the hammer blow came down the flea would be long gone.

I'd say a better analogy is that we are fumigating a room to kill all the fleas in a room before they multiply and invade all the rooms in the house.

I'd argue that the Plan B advocates seem to be aiming for something that looks more like standing in the room, with a quarter of the people roped off on one side of the room and then using cans of fly spray and trying to eradicate the fleas.

As we all know, if you fumigate a room you have a better chance to control the pests but you have to step outside until the fumes subside. That is what the lockdown - or as it might be better called, the rahui period - is really about.

The question now is how long we have to stay out of the room. We will know the answer to that in the next few days or weeks but Plan A gives New Zealand a real chance to be one of the first in the world to get back to "normal".

With this, we will get as much as possible of the economic and social pain out of the way as soon as possible in a way that many countries in the rest of the world just can't.

So let's stick to Plan A.

• Professor Peter Shepherd, who was awarded the Royal Society of NZ Callaghan Medal for Science Communication in 2017, is a University of Auckland scientist focusing on the development of new treatments for diseases.