Science – Covid19: Beware second wave

The Covid-19 situation in New Zealand at present is at a crossroads: the number of new cases is approaching zero, but is not quite zero. The small business sector is severely financially stretched after more than a month of closure, and hence no income due to the national lockdown at Levels 3 and 4. The Government financial support is very helpful but is at the margin of survival. My own family has a business, which is in that precarious position. Many are now asking – should New Zealand, which seems to be at the international forefront of Covid-19 recovery, simply get back to work?

The reason for the NZ Government’s caution in responding to that question lies in the possibility of a second wave of Covid-19 infection and the associated possibility of another period of deep lockdown with massive economic damage. Actually, this caution is also evident in the response of leaders in other countries seeking to recover from Covid-19, including the Prime Minister of the UK and even the President of the USA. History, including the catastrophic global 1918 flu pandemic, tells us that second wave re-infections are usually more fatal and more extensive than first waves.

Where have second waves appeared in 2020 and where are they expected to occur? The widely respected Dr Fauci – the Covid-19 spokesperson for the US administration – has stated that second waves are almost inevitable in the US and are likely to coincide with the usual flu season, thereby overloading the hospital system even further. There are a number of zones in the US, including Las Vegas and the state of Georgia, which have prematurely opened their economies and which are regarded as being at high risk of a second wave by the health authorities and even by President Trump. Singapore has recently experienced a second wave, attributed to overseas workers returning and living in crowded apartments.

Overcrowding could also affect Auckland, as this has been a serious issue in some communities for many years. Hokkaido, the northern island province of Japan (similar in many ways to New Zealand, including the size of its population), has had a second wave infection appear after establishing good control during the first wave. China, including Wuhan where Covid-19 was first detected, is carefully monitoring the possibility of a second wave given the potential economic impact of re-infection.

What causes pandemic second waves? There are several factors including, firstly, small “seed pockets” of asymptomatic individuals who have not yet been identified by testing and who become transmitters and initiators of the second wave. Secondly, despite closure of borders, there are the occasional positive cases returning home to New Zealand from overseas, who are not adequately quarantined. Thirdly, the level of Covid-19 immunity amongst the broader New Zealand community remains unclear at present. The wider community will have no prior immunity against this new global virus. Also, even those who have recovered from first wave Covid-19 may or may not have full immunity. Second wave mortalities are likely to be prevalent among vulnerable cohorts, including older people over 65 and those with respiratory pre-conditions. A recent concern relates to young children, who were originally thought to be at lower risk, but now appear to be vulnerable to Covid-19 related infections, according to sources in the UK.

The need for social distancing is, therefore, more important than ever during this period of uncertainty. Recent research on the dispersal of aerosols (tiny, very light droplets of mucus) incorporating Covid-19 virus has shown that the two-metre separation rule may be a minimum precautionary distance and more vigorous sneezing and coughing is likely to spread the virus containing aerosols much further than two metres. Also, slight breezes or winds are capable of spreading the virus in many directions – not just in a forward direction.

New Zealand needs to become more aware of the statistics of Covid-19 infections overseas. The Worldometer Covid-19 matrix is a very good place to start. The Covid-19 virus is essentially the same the world over. The virus in New Zealand is the same as the virus currently causing chaos in New York, London and in the European Union.