The COVID-19 situation in Australia is fast-moving, with unexpected developments almost every day. From an initially robust vaccination drive, there are now signs of a slow-down in immunisation rates among people in New South Wales. At a time when lifting of lockdown restrictions in the state depends entirely on vaccine coverage, what does a slowdown indicate? Why is 70 percent coverage deemed a magic figure that promises a return to pre-pandemic freedoms and how has the mixed messaging around AstraZeneca contributed to vaccine hesitancy? Prof Christine Jenkins, Head of the Respiratory Program at The George Institute answers some of these questions to bring clarity in these uncertain times.
Past COVID-zero
At some point it seemed Australia could aim for an elimination strategy, but the Delta variant appears to have quashed that possibility, at least in some states. Prof Jenkins agrees, “Yes, we are well past COVID-zero. Delta is so contagious that it will spread wherever adults and adolescents go. Hence a zero COVID approach is only possible if people do not move about or congregate indoors. It may also be possible if 95 percent of people are vaccinated.”
But she believes that is an unrealistic threshold even with childhood vaccinations. Therefore, like most countries who have dealt the outbreak long before Australia, a robust vaccination drive and ‘managing’ case numbers, rather than ‘eliminating’ the virus, has emerged as the most pragmatic strategy to return to pre-COVID times.
NSW government has set targets of 70 and 80 percent full immunisation coverage for a staggered return to normal. On current trends, 70 percent of the eligible NSW population will be double vaccinated by mid-October. The target figures are based on advanced epidemiological modelling which predicts these numbers as the watershed mark to be able to co-exist with the virus with manageable risk.
“This means that 70-80 percent of eligible adults are unlikely to get the infection when exposed, and if they do pick up the infection, they will be very unlikely to have a severe episode requiring hospital admission. However, the modelling suggests that thousands of people may have the virus in Australia at any one time, even if we are 80 percent vaccinated – this will depend on the season and many other factors as well. Vaccinated people however will be far less likely to transmit SARS-CoV2. The community will be functioning almost normally again.”
But high vaccination rates will not mean we can do away with other COVID-safe measures, namely social distancing, maintaining hand hygiene and mask-wearing, among others.
“We will still be using QR codes to check-in at most places, as well as likely using a vaccination ID to enable safe entry to events and venues,” Christine added.
Vaccines: our best ‘shot’
There have been concerns about the capacity of hospitals and staff to manage the anticipated surge of patients in NSW in the next few weeks. Prof Jenkins’ mantra to overcome this challenge is simple. “Vaccinate, vaccinate, vaccinate! This will keep us from reaching an even higher peak.” She says hospitals are prepared with increased ‘hardware’ such as ventilators and NIV machines but it’s the staff that are the main cause of the worry.
“The really important resource is healthcare personnel – nurses and doctors, but staff at every level of the healthcare system. Rosters are being run now to conserve some staff, wards are allocated to COVID care with a traffic-light system for the sickest (red) down to those almost ready to be discharged (green). The healthcare system is more flexible than we think and has the capacity to de-prioritise some routine services and move staff to centres of need.”
Compared to most countries, Australia has been fortunate in successfully averting the health crisis and collapse of health systems seen elsewhere. Fatalities and hospitalisations have been far fewer too, even though the hospitals in the LGAs of concern at present are bearing a very heavy load. But while most countries have passed the peak of the pandemic, we are battling our worst outbreak now. What lessons can we learn?
“The vaccines work. There is about 90 percent protection from two doses of either AstraZeneca or Pfizer in preventing hospital admission, risk of intensive care admission or death,” says Prof Jenkins, spelling out the biggest learning. “We lost several precious months early this year in getting people vaccinated and protecting them against the outbreaks that are now causing so much personal hardship and economic fallout.”
The numbers in perspective
The fuss around AstraZeneca only made matters worse. Christine says, “Risk estimation can be a bland statistic, or it can be made real when it is contextualised. When compared to the risks of a range of familiar activities, the risks of blood clots with an AstraZeneca vaccination can be framed in a more accessible and convincing way.”
Putting the numbers in perspective, she compares the risks of blood clotting from the vaccine with other ‘everyday’ events. “One in every 1000 women who take the contraceptive pill will develop blood clots. Giving birth (1-2 in 100,000), taking an aspirin (1 in 10,000), hang-gliding (1 in 125,000), scuba diving (1 in 200,000), driving (28 in 1,000,000), taking a bath (1 in 685,000 over a year) and a range of other activities people choose to engage in have far greater chances of death than the AstraZeneca vaccination.” Most importantly, getting COVID-19 has a dramatically greater chance of causing death from clotting than receiving the AZ vaccine. As well, the likelihood of getting COVID-19 moves much closer to certainty if you are not vaccinated.
As vaccination rates increase and reach those already achieved in other countries, there is one more phenomenon we must be prepared for – breakthrough infections. These are when a fully immunised person gets infected with COVID-19. They are on the rise in most countries that have achieved high vaccine coverage. But the risks of severe illness, hospitalisation and death are reduced in these cases.
“Breakthrough COVID infections in vaccinated people can still occur. This has been shown in some high exposure settings such as in healthcare workers, where these have occurred in up to 20 percent of people, but fewer than 1 percent of these people become seriously ill. Breakthrough infections are more likely as immunity wanes, and the longer is the time after vaccination.”
Fighting fit
It is well known now that different sections of the population face varying risks from COVID-19. Older people, especially those with co-morbidities, have a higher chance of severe illness, while children are at minimal risk of complications.
Prof Jenkins calls this ‘immune fitness’. “Immune fitness is my term, and I use it to refer to the capacity of our immune systems to respond with optimal antibody and cellular responses to an infective insult, whether naturally occurring or delivered by vaccination. Younger people and people without any comorbidity, and those not requiring any immunosuppressive therapies, have greater immune fitness than older people and those with comorbidities.”
She says that while age and other inherent factors cannot be altered, some factors can be controlled to strengthen the body’s resilience. “Immune fitness can’t be enhanced by any single strategy – healthy eating, maintaining regular exercise and sleeping well are the best ways to preserve your immune fitness.”
