The changes to COVID-19 close contact rules in NSW and Victoria, which come into effect at 6pm on Friday in NSW and 11.59pm in Victoria, do not represent a substantial change in risk management because the current rules only apply to a fraction of households with infections.
But the changes are significant because they represent a move away from a rules-based approach to managing this pandemic and a shift towards the public health strategies usually used to combat infectious diseases: providing people with information they can use to mitigate a health risk, backed by diagnostic tools and treatment to manage disease.
NSW and Victoria will end isolation rules for household contacts of COVID-19 cases.Credit:Janie Barrett
Over the past few months, NSW and Victoria have almost been in sync when it comes to the easing of COVID-19 rules. After these changes come into effect they will look even more alike when it comes to managing community infections.
The biggest change is that close contacts of cases will no longer need to quarantine. Instead, those who are at an elevated risk of incubating the virus and becoming infectious, but who remain symptom-free and negative on rapid antigen tests, will be asked to wear a face mask when indoors or in high-risk settings outside the home, to have a daily negative RAT before coming into close contact with people outside their household, to avoid contact with the elderly and immunocompromised where possible, to work from home where practical and notify their employer/educational facility that they are a close contact.
The home remains one of the highest risk settings for transmission, and it is important people understand and manage that risk. At the moment, we have strict rules in place for those who test positive to COVID-19 and their household contacts. But only a fraction of cases are diagnosed and reported and the strict rules around household contacts may discourage a person from testing because of the impact a positive diagnosis can have on his or her housemates.
Many infections in the community are never identified because people are asymptomatic and have no known exposure that would prompt them to test. Other people ignore symptoms or do not report positive rapid antigen test results. There are also false negative results, especially with home use RATs. If you do the numbers, this translates to less than 50 per cent of infections being reported.
Only a fraction of COVID-19 cases are being detected in Australia.Credit:Louise Kennerley
Isolation rules also only apply for seven days from the index case’s positive test, or from a person’s last contact with an index case, if they continue to test negative during that time. This fails to encompass the entire infectious period for many household contacts who test positive; they may well have been the first person in the household to get sick and be clearing the infection by the time the house records its first positive case. The index case would also have been infectious before they tested positive, often for some days.
It would have been helpful to know the proportion of household contacts that go on to test positive within the seven-day isolation period, and how this has changed over time, to estimate the actual risk these latest rule easing might add, but this is likely to be marginal given the isolation time only covers a part of the infectious period for the fraction of the cases that are reported, and for the fraction of their contacts who also become infected – at least the portion who comply with the isolation rules.
High recent infection rates mitigate the risk against reinfection, especially in a highly vaccinated population – 10 per cent of the Australian population have reported an infection within the last two months and the true number of recent infections may be double that. Our risk of new infections will fall as more people get vaccinated and the proportion of people with a history of infection rises. The booster rollout has also reached 50 per cent of the population, or more than two-thirds of those eligible and uptake is highest in those more vulnerable to serious illness.
As the likelihood of infection within a household declines, so too does the efficiency of the measures in place at the household level. We end up with more people away from work or school who will not develop an infection and be a risk to others.
Children are missing school despite testing negative to COVID-19.Credit:Rhett Wyman
By removing the precaution of quarantining close contacts, whilst maintaining testing and safety advice, we might see more index cases tested and reported, and more contacts test positive with the daily testing requirements. It is possible we will then benefit from better detection and management of known infections.
Rules are only one means of encouraging safe behaviours in our community. They are essential to protect individuals, our healthcare systems, and the population as a whole. But the sheer infection rates in our community mean these rules have changed from monitored and enforced requirements, to being fully reliant on the willing compliance of the public. This means they can be safely replaced by clear public health messaging, tailored to reach all in our community.
Some argue that rules are still needed because they get across the public health message that it is still important to manage infection risk, but, again, this is not the only way to communicate the ongoing importance of infection control. Clear and timely information on changes in exposure risk, or about new variants, will allow us to make informed decisions about our actions.
Herd immunity is not attainable, as it only holds when the pathogen doesn’t mutate, or, if it does, when existing immunity protects people from the new strain. Unfortunately, we may never have sufficient immunity at the population level to prevent the COVID-19 virus from establishing new waves of infections, because there is too much immunity-escape occurring between variants.
That said, the range of possibilities for new variants is becoming increasingly more limited. The hope is that the rate at which new variants of concern appear will slow, but it won’t be zero. Because of this, we need to keep some stricter prevention and control measures up our sleeve. Any measures used to control COVID-19 through the long tail of the Omicron wave must be sustainable, and employed judiciously, to preserve their effectiveness over the winter and for future public health responses.
Professor Catherine Bennett is chair of epidemiology at Deakin University. She is a leading researcher and teacher in public health.
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