Covid quarantine cut to a week – Expert Reaction

The timeframe for mandatory self-isolation will soon drop to a week as the Omicron outbreak grows.

Starting from Saturday, people who test positive to Covid-19 – and their household – will have to isolate for a 7-day period, down from ten days. Covid-19 Minister Chris Hipkins said that if others within the home develop symptoms they should get tested (in addition to their 3 and 7 day tests) and isolate if positive for a further seven days from that test.

The SMC asked experts to comment. 

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

“The reduction in isolation period for cases from 10 days to 7 days is in line with Australia and is based on evidence that the majority of people are no longer infectious by this time. However, some people may be infectious for longer than 7 days and it would be preferable to use a “test to release” approach where people take a rapid antigen test on day 6 and day 7 and can end their isolation period if both tests are negative. This would minimise the risk of people going back into the community while still infectious, while still allowing most people to shorten their isolation period to 7 days. This was the system used in the UK during their Omicron wave.

“Test to release” is even more important for household contacts because they could potentially get infected partway through their isolation period. For example, a household contact could still be in the incubation period on day 3 and get a false negative on day 7. Doing an additional rapid antigen test on day 6 would reduce the chance of this happening.

[Note: The above para replaces the previous:
“For household contacts, the situation is a bit more complicated because they could potentially get infected partway through their isolation period. For this reason, household contacts will need to do a rapid antigen test on day 3 and day 7. If either test is positive, they will need to isolate for a further 7 days after the positive result.]

“It would also be helpful if non-household close contacts could be given access to RATs. Although they are not required to isolate, having access to tests would enable close contacts to check their infectious status before going out into the community.

“Of course, anyone with any Covid-like symptoms should stay at home regardless of what the test says.”

Conflict of interest statement: Michael Plank is partly funded by the Department of Prime Minister and Cabinet for research on mathematical modelling of COVID-19.

Emily Harvey, Senior Researcher at Market Economics, Lead Researcher at COVID-19 Modelling Aotearoa, Principal Investigator with Te Pūnaha Matatini, comments:

Shortening of the isolation period for cases:

“NZ was following the guidance that confirmed cases needed to isolate for 10 days, and could leave isolation without testing. Following these rules, UKHSA modelling estimates that 5% of people would still be infectious at this point. This same modelling found that the self-isolation period for confirmed cases could be shortened to 7 days for people who have returned two negative RATs on days 6 and 7 and don’t have symptoms, with no additional risk. The RATs (or LFTs as the UK call them) are crucial for working out who is most likely to still be infectious at that day 7 point. Shortening the isolation period to 7 days without requiring negative test results more than triples the number of people who would still be infectious to 16%.

“It is disappointing that NZ has chosen to shorten the isolation period for confirmed cases without this important safeguard. In workplaces where people work in close proximity to others, this change in rules risks increasing transmission in those workplaces and worsening staff shortages. The evidence-based recommendation is to follow the UK guidance if you can (two negative RATS at least 24 hrs apart to leave isolation). This however requires people to have access to more RATs than the government provides in its current rules, and will only be available as an option to those who can afford to purchase RATs from retailers.”

Shortening of the isolation period for household contacts:

“With a virus as infectious as the Omicron variant, unfortunately a high proportion of household contacts will get infected. Whilst the majority of infections from the first case in the household will take place in the first week (as Minister Hipkins states), there is then an extended period of time (3-5 days) before someone would test positive on a RAT. This means that a large proportion of household contacts who get infected would not test positive until after day 7. This is even before considering the possibility of chains of transmission within a household, when the household is more than two people.

“The safest option is to isolate for 10 days from when the most recent person in your household tested positive or had symptom onset. This is what the policy was in some of the earlier phases and when we had an elimination strategy. This extended isolation period is especially hard for larger households or people who can’t work from home. In these situations, international recommendations are that even if not officially ‘isolating’, these people, who are at high risk of being infected, should wear masks whenever indoors and should avoid any close proximity or high-risk settings. Other countries have provided daily RATs for people in this situation to help them detect infection early and reduce onward transmission. This would be another way to reduce the official isolation requirements, while keeping the risk low. Reducing the isolation rules for household contacts without providing daily RATs and good quality masks, greatly increases the risk of onward infection.”

Modelling results for the total number of people in isolation:

“Detailed individual-based modelling (which includes household structure) shows that the peak of people in isolation (cases and household contacts combined) occurs at around the same time as the peak in the daily confirmed cases. The peak in the number of household contacts needing to isolate actually occurs earlier, due to the large proportion of case numbers that come from household contacts that go on to test positive with a virus as infectious as Omicron.

“This means that, in Auckland at least, we are hopefully at the point where the workforce impacts due to isolation requirements are at their worst. If we keep the 10 day isolation period, the impacts should decrease from here. However, if we increase transmission rates by shortening the isolation period, we risk creating more transmission and a longer plateau, with disruption for longer, or even second peak, with greater disruption than we would have had if we had not reduced the isolation period.

“As an additional note, increasing the testing frequency to more than just on day 3 and day 7 could help to detect household cases early, which would have the benefit of shortening the time that these people would need to be in isolation, while not increasing the risk of transmission at all.”

Conflicts of interest: I, along with others from COVID-19 Modelling Aotearoa, am funded by the Department of Prime Minister and Cabinet to provide advice on the COVID-19 response and from a Health Research Council grant designed to help ensure equitable health and wellbeing outcomes for all New Zealanders during the COVID-19 pandemic, and future infectious disease threats in Aotearoa.

Associate Professor Lynn McBain, GP and Head of Department of Primary Health and General Practice, University of Otago, Wellington, comments:

“This is welcomed and the explanations in the Minister’s press release refer to the evidence.

“As someone who has spoken with large numbers of patients who have tested positive and are isolating at home, there is some confusion / lack of clarity for the public about self-isolation and what household contacts are expected to do regarding testing.

“Many Covid-positive people believe that they as well should test on day 3 and 10  so that they can be let out of isolation themselves. Not everyone has the ability to search through the websites to source the needed information.

“There is also a challenge with this press release’s timing – that the change does not come into effect until 11.59 pm on Friday. We have already this afternoon at our practice had a large number of patients ring and ask if they can be let out of isolation early – if, for example, they are now at 7 days. It would have been better to announce this on Friday, or to start the 7-day isolation policy today. Some clear messaging about the timing of the changes in the media coverage would be great.

“General practices are very busy trying to keep up with patient queries about all aspects of Covid care, so clear media messages will help the care burden too.”

Conflict of interest statement: Dr McBain owns a general practice in Wellington.

Dr Dianne Sika-Paotonu, Immunologist, Associate Dean (Pacific), Head of University of Otago Wellington Pacific Office, and Senior Lecturer, Pathology & Molecular Medicine, University of Otago Wellington, comments:

“It was indicated by the Minister for Covid-19 Response Hon Chris Hipkins, that changing the isolation period would allow workers to get back to work more quickly and reduce the impact on business operations, while at the same time breaking the chain of virus transmission in the community. Reasons given for the shorter isolation period included many Omicron transmissions were reportedly occurring within a 7-day timeframe and lower Covid-19 reinfection risk within the first 3 months after being infected with Omicron.

“In the meantime, the highly transmissible Omicron variant of the SARS-CoV-2 virus is continuing to spread rapidly across Aotearoa New Zealand with 22,454 community cases reported today, 742 people in hospital, 19 in ICU/HDU and sadly 4 who have passed away – sympathies and condolences are respectfully extended to all family, whanau and kāinga at this time.

“The actual true Covid-19 case numbers in Aotearoa New Zealand are likely to be much higher than those being reported, with the majority of case results from rapid antigen testing. Full understanding of transmission patterns in households and communities will be difficult without widespread testing, and test results – it is important that all rapid antigen test results are recorded in My Covid Record, even those that are negative.

“We also remain in the process of protecting vulnerable communities that include our children, tamariki and tamaiki aged 5-11 years, and getting people boosted to protect them from Omicron. Vaccination Inequities with respect to Māori and Pacific peoples, tamariki and tamaiki are again evident in booster and vaccination levels for our children, tamariki and tamaiki aged 5-11 years.

“Of those affected by the current outbreak in Aotearoa New Zealand, a total of 87,415, 31% (nearly 1/3) were children, tamariki and tamaiki and rangatahi aged 19 years and under, with this group also making up 12% of all hospitalisations.

“Of those children aged 5-11 years, 52.6% of the general population have received their first Covid-19 vaccine dose, and for Māori and Pacific tamariki and tamaiki, vaccination levels for first doses are only at 33.2% and 45.3% respectively.

“Of all those currently eligible for a booster dose of the Covid-19 vaccine, 72.5% of the general population have received theirs, and for Māori and Pacific, boosters levels are at 59.9% and 59.5% respectively.

“We still need to do everything we can to slow down the spread of Omicron while our children, tamariki and tamaiki get vaccinated, and to for people to get boosted.”

No conflict of interest declared.