What do the latest Covid trends mean? – Expert Q&A

The number of newly reported Covid-19 cases is growing in Aotearoa. Since Friday, it has reached the thirties or forties each day, with a jump to 60 cases on Sunday.

The overall case trend has risen recently.

The SMC asked experts to explain what the current trends are telling us.

Dr Amanda Kvalsvig, Epidemiologist and Senior Research Fellow, Department of Public Health, University of Otago, Wellington:

What are the trends telling us?

“These trends show that it’s time to talk about a circuit-breaker. A move back to Alert Level 4 is the best and probably only chance of reversing these highly-concerning trends that are all moving in the wrong direction. Vaccination is not going to happen fast enough to reverse these trends and we need to buy time.

“Before deciding on Aucklanders’ behalf that they’re too tired of lockdowns, let’s hear from Aucklanders. Let’s also hear from Māori, Pasifika, people with underlying conditions, people who are marginalised, and children and their advocates. They’re the ones carrying the highest risk if Covid-19 is allowed to spread before vaccination rollout is complete.

“Ruling out Alert Level 4 will effectively also rule out Alert Level 1, leaving Aucklanders in the worst of both worlds with a large number of restrictions and a large – and growing – number of cases, hospitalisations, and deaths. That situation is no good for businesses either. We’ve seen this pattern play out again and again in multiple countries.

“A far better option would be for Government to put multiple protections in place for those experiencing hardship including benefits and payments, funding for workforces, Pātaka Kai (local food-sharing initiative), emergency support for mental health, housing, and safety from violence, and many other resources. With substantial support measures in place, movement restrictions can be made tolerable for people while chains of transmission are being stamped out.

“This is the most urgent and most important national conversation we can be having right now. At this critical point in our pandemic journey, failing to act decisively will have severe consequences for population health and wellbeing. Any decisions made now need to be highly transparent and guided by the widest possible consultation with the people of Aotearoa.”

No conflict of interest.

Associate Professor Collin Tukuitonga, Associate Dean Pacific, Faculty of Medical and Health Sciences, University of Auckland, comments:

What are the main trends so far in New Zealand’s outbreak?

“In recent days, we are seeing a ‘saw teeth’ pattern of new cases, but the trend is increasing overall. Most of the cases are among Māori and Pacific people. I don’t have access to data on the ethnicity of the ‘mystery’ cases, but I imagine that most or at least many will be Māori and/or Pacific. The overall trend upwards is a concern.”

How has Auckland’s move to Alert Level 3 affected these trends?

“The move down to Level 3 and some relaxation of public health measures would have permitted more movement of people (over and above people who break the rules), and increased the spread of Delta. We can expect to see the full picture 10-14 days from Monday 6 October, which is around 20 October.”

What are the key ethnicity trends? 

“Most of cases are Pacific and/or Māori. The Māori case numbers are increasing, while Pacific case numbers are steady or declining.”

What are the trends telling us? 

“The outbreak is affecting vulnerable populations – Māori and Pacific, those in transitional housing, and others in difficult socioeconomic circumstances. This is predictable in many ways given the history of pandemics and social disadvantage. Māori had a death rate that was more than 8 times higher than that of NZ Europeans in the 1918 pandemic.”

How do our current trends compare with NSW and Victoria? 

“There is a similar pattern but it’s not on the same scale. I am not sure of the ethnic breakdown in NSW and Victoria.”

What is known about the impact of the anti-lockdown protest on Sat 2 Oct?

“This is unclear because we are unable to link protesters with new cases, although it seems probable that disaffected and unvaccinated people would have been the main protest participants. This means that the risk of infection is higher in these groups.”

No conflict of interest declared.

Dr Janine Paynter, Senior Research Fellow, Faculty of Medical and Health Sciences, University of Auckland, comments:

What are the trends telling us?

“We are already seeing what is likely to be an effect of the vaccine in this current outbreak. Around 66% of the population have had one or two doses of the vaccine. Only 8.5% of the cases are vaccinated.

“Low vaccination rates are highly likely to be attributable to difficulties accessing the vaccine especially in rural and remote areas, or where a lot of the population work long hours or are carers who find it hard to get away from responsibility.

“It is imperative we reduce these barriers quickly: taking the vaccines to where people are, opening vaccination clinics or sites for longer, and encouraging employers to specifically ensure their employees are given time to get vaccinated.”

Conflict of interest statement: “Some of my work on vaccines and infectious disease is funded by GlaxoSmithKline (GSK) a company that manufactures and sells pharmaceuticals including vaccines.”

Professor Michael Plank, Te Pūnaha Matatini, and School of Mathematics and Statistics, University of Canterbury, comments:

What are the main trends so far in New Zealand’s outbreak?

“It’s very clear the outbreak is growing at present. All the key indicators have been trending upwards in the last two weeks, including total cases, unlinked cases, cases infectious in the community and the number of contacts. On the current trend, the number of new cases is approximately doubling every 12 days. If that continues, we would be seeing around 160 new cases per day by early November. Because we still have a lot of people who aren’t yet fully vaccinated, that level of cases would mean a large number of people needing hospital treatment.”

What are the trends telling us?

“Over time, increasing vaccination rates will help to slow transmission down and hopefully turn the tide on the growth of cases. However, in the meantime there is a danger that too many cases could mean our contact tracing system struggles to keep up with demand, leading to an acceleration in cases. This means we need to do everything possible to minimise community transmission, particular in the next few crucial weeks as we get more people double-dosed.”

How does NZ’s Covid-19 situation compare to Victoria or New South Wales?

“Our outbreak is currently growing slightly slower than the one in Victoria, Australia, was at a comparable point in time.

“However, a slight increase in the transmission rate would put us on a similar trend to the one Victoria was on in mid-August. Eight weeks later, Victoria has over 600 Covid patients in hospital and around 130 in ICU. If this happened here it would take a terrible toll on our healthcare system.”

What is known so far about the impact of Step 1 of Auckland’s roadmap?

“It’s still too early to say whether the move to Step 1 of the Auckland roadmap has contributed to a significant increase in transmission. But even a small increase could spell big trouble. So it’s essential people play it safe and stick to the rules: keep it outdoors and wear a mask.”

Conflict of interest statement: “I am partly funded by MBIE for research on mathematical modelling of COVID-19.”

Dr David Welch, Senior Lecturer, Centre for Computational Evolution and School of Computer Science, University of Auckland, comments:

What are the main trends so far in New Zealand’s outbreak?

“The number of COVID cases in Auckland is rising, with the reproduction number R now well above 1. The consensus estimate is that R is currently around 1.3.

“At that level it takes about two weeks for cases to double, so where we currently see about 25 new cases infectious in the community every day, in two weeks we can expect to see about 50, and 100 in a month. That rate of increase will soon start to put serious pressure on health systems. It will also start to stretch the abilities of the contact tracing teams to track and isolate close contacts. Publicly available estimates suggest that the contact tracing system will struggle when there are somewhere between 100 and 200 cases infectious in the community for a sustained period.”

What are the trends telling us?

“All this indicates that renewed effort needs to go into suppressing transmission. To safely loosen of restrictions further (such as to the proposed Step 2 of the Auckland roadmap), community transmission needs to be lower and the number of fully vaccinated people much higher.”

What is known so far about the impact of Step 1 of Auckland’s roadmap?

“When changes are made to restrictions, it takes around 10 days for the effect to be clearly seen as first transmission needs to occur (or not), then be detected. The changes introduced at Step 1 were relatively mild – allowing outdoor, distanced interactions with a few people – and there is no sign in the case data yet (7 days in) of any effect.”

What do rising Auckland cases mean for regions in Alert Level 2?

“The border restrictions and careful monitoring of regions outside of Auckland can work to keep those areas safe and open. If cases are detected in regions currently in Level 2, rapid moves need to be made to stop the spread and eliminate the virus from the region. Failure to do so risks extensive local spread and could make local elimination very difficult. As we have seen in Auckland, if transmission is established in a region then Alert Level 3 may only be enough to suppress transmission, not eliminate it. The implication is that if other regions see sustained transmission, they may be stuck in Level 3 for a long time like Auckland is.”

Conflict of interest statement: David is providing analysis to the Ministry of Health on genomic testing of cases.

Dr Matthew Parry, Senior Lecturer, Dept of Mathematics & Statistics, University of Otago; and Principal Investigator, Te Pūnaha Matatini, comments: 

What is the rise in contacts telling us?

“While a lot of the current focus is on the vaccination drive, alert level 3 restrictions and the heroic efforts of testing and contact tracing teams are buying us the time to get the job done.

“Unfortunately, the trends in the number of active contacts being managed suggest contact tracing is going to be increasingly challenging. Currently, the number of active contacts being managed is doubling every 8-9 days, which is faster than the growth in the number of new cases.”

Conflict of interest statement: “I am a member of Te Pūnaha Matatini’s COVID-19 research team, along with the authors of this study, and am partly funded by MBIE for research on mathematical modelling of COVID-19.”

Dr Dion O’Neale, Principal Investigator, Te Pūnaha Matatini; and Lecturer, Physics Department, University of Auckland, comments:

What are the main trends so far in New Zealand’s outbreak?

“All the indicators suggest that we are back in a growth phase of the epidemic, with case numbers on an upwards trajectory – and not just a random spike. In such a situation it is very tough to vaccinate our way out of the growing case numbers.

“In addition to not offering complete protection against infection, vaccination takes a couple of weeks to develop a full immune response, even without accounting for the need to have a gap of three or more weeks between first and second doses.

“In contrast, after exposure, people infected with COVID are able to infect others within only a few days. During a growing outbreak, it is easy to have several generations’ worth of infections before a surge in vaccinations is able to have an effect on transmission reduction.

“There’s a strong case to be made for a temporary return to Alert Level 4 in Auckland as a circuit-breaker to limit transmission for a few weeks while we try to get as many people vaccinated as possible. We wouldn’t expect this to get us to zero cases in a short time, but it would mean that we are able to get more vaccinations to under-protected groups both inside and outside Auckland. It would have the added benefit of allowing contact tracers to potentially ring-fence some more of the sub-clusters in the outbreak, due to the reduced numbers of contacts.”

How has Auckland’s move to Alert Level 3 affected these trends?

“The move from Alert Level 4 down to Level 3 in Auckland, and subsequently to Step 1 of the 3-step plan, allows for people to have more social and workplace interactions than previously. We know from looking at the properties of interaction networks that only a small increase in the number of connections between households, via social interactions or extended bubbles, can lead to a huge increase in the size of connected components in an interaction network. Increasing the number of inter-household connections from about 5% to  about 10% increases the size of the biggest component in an interaction network from tens of thousands to well over a million.

“Doubling the number of interactions can easily increase the size of the pool of possible people who might be infected by more than a factor of ten. This is why it’s so important that people are making sure to minimise the risk of transmission for any of these new interactions. This means doing things like wearing well-fitted masks, interacting outside or in well ventilated areas, keeping physical distance, and of course being vaccinated and meeting with others who are also vaccinated. It is also why it’s important for people to still minimise the number of different interactions they have with others, even if they are only meeting people one household at a time.”

What are the key ethnicity trends? 

“The current outbreak has reinforced what we already know from other communicable diseases – infections spread more in, and lead to worse health consequences for, people in crowded or tenuous accommodation, or dwellings which are poorly heated and ventilated. It will also spread more through groups where people are unable to easily isolate at home and who have under-served health needs. It is no secret that Māori and Pacific peoples are over-represented in some of these groups. The current outbreak has reminded us that if we want any of us to be safe from COVID transmission then we need to address some of the social and economic inequalities that can drive increased disease transmission.

“We’ve seen that while there has been an overall surge in vaccinations during this outbreak, this uptick hasn’t been distributed evenly. Vaccination rates for rural communities and for Māori are still low in many places. Work from others (e.g. the map of distance to vaccination centres produced by the Spinoff) has highlighted the difficulties that some communities face in getting vaccinated. This can be because of a range of factors: from distance to vaccination centres, to difficulty getting time off work or other commitments, to simply a lack of information or trusted advice.”

What are the trends telling us?

“We know from both international and local evidence that it is younger people who are much more likely to be mobile and to have increased interactions, and hence higher rates of transmission, whether this is from increased chances of them being essential/on-site workers or from higher levels of social interaction. This is concerning in Aotearoa because younger people were the last to have access to vaccines with many only recently having access to a first dose.”

What is known about the impact of the anti-lockdown protest on Sat 2 Oct?

“Nine days is long enough ago that we could start to see any potential transmission from the protest showing up as new symptomatic cases, and it is now 11 days since the protest. Only contact tracing, however, will be able to say what the actual consequence of the protest was. If no one at the protest was infectious at the time, it may not have led to any additional cases. It was nonetheless an unnecessary and potentially dangerous transmission risk.”

What is known so far about the impact of Step 1 of Auckland’s roadmap?

“When alert levels or other transmission interventions change, it takes time for the effect of those interventions to flow through into things that we can observe, such as the number of new detected cases or the number of hospital admissions. At the start of this outbreak it took well over a week to see the full effect of the move to Alert Level 4. In that case there was a large change in the transmission environment.

“With moving to Step 1 of Auckland’s three-step plan, we’d again expect it to take a couple of weeks for the effect of the transmission environment to flow though into observable consequences like new reported cases and hospital admissions.

“Part of the reason for this is that there is a incubation period after infection, before people develop symptoms. Also, even with Delta, exponential increases start off looking like a slow rate of growth, when there are initially only a small number of cases infecting a few new people each. This quickly transitions into very rapid growth if there are not sufficient interventions to suppress transmission.

“During this period, while the consequences of changing the transmission environment are still uncertain, it would be risky to make further changes that create additional transmission risks.”

Conflict of interest statement: “I, along with others from Te Pūnaha Matatini, am funded by Department of Prime Minister and Cabinet to provide advice on the COVID response and from a Health Research Council grant to look at equity related to COVID in Aotearoa.”