Herd immunity from COVID-19 is the long-term goal, the Australian government has confirmed — but its initial focus is to deliver protection and make vaccines available as soon as possible.
But the lower efficacy rate of AstraZeneca’s vaccine, which will be used to vaccinate the majority of Australians, has raised concerns around whether this is even possible. Trial results suggest it has an efficacy rate of 62.1% in two standard doses. Efficacy increases to 90% with a low dose followed by a standard dose.
In comparison, standard doses of Pfizer and Moderna’s mRNA vaccines have shown 95% and 94% efficacy, respectively.
Should herd immunity be the goal — and is it possible?
What is the government saying?
None of the major vaccine candidates have been out long enough to know long-term transmission effects — that is, if people vaccinated against COVID-19 can still carry the virus and pass it onto other people. We also don’t know how long a vaccine will be effective for.
The data we do have shows the vaccines, including AstraZeneca’s, prevent serious illness — so getting as many Australians vaccinated as possible is key.
“Herd immunity is often referred to as between 60 and 66%, but our goal is to make sure that, amongst the adult population, that we have a very, very high take-up rate,” Federal Health Minister Greg Hunt said last week.
He added the AstraZeneca vaccine was considered a better candidate due to the issues around distributing an mRNA vaccine, like Pfizer’s and Moderna’s, which need to be stored at -70 degrees.
Is this enough?
Australia has high vaccination rates — even during the pandemic last year, vaccination rates for five-year-olds reached record highs of 94.9%.
But the lower the efficacy of a vaccine, the more people will need to get vaccinated for it to be effective, Swinburne University’s School of Health Sciences dean Professor Bruce Thompson tells Crikey.
Focusing on severe illness, he added, should be a priority.
“3% of people who develop the disease die, and 10 to 15% had rapidly accelerating disease,” he said. “Taking the vaccine means you don’t get severe illness, go to hospital, or are hammering at death’s door.
“Ultimately if we can get over 60% of the population vaccinated that should make a profound difference in terms of us living with COVID.”
Whether this is enough to open Australia’s state and international borders remains to be seen.
“I think it will make a difference … The whole population will be in the same boat,” Thompson said.
Will the government make it mandatory?
The government quickly backtracked on comments made by Prime Minister Scott Morrison in August when he suggested the vaccine would be “as mandatory as you can possibly make it”.
So it will be voluntary, but just because the government isn’t mandating vaccinations, that doesn’t mean private companies won’t. Corporations can legally make vaccines a condition for working or using a service like attending an event or catching a flight. Qantas CEO Alan Joyce has already flagged that passengers travelling internationally might have to prove they have been vaccinated against COVID-19.
Thompson stressed vaccine mandates were pretty normal.
“The flu vaccine was mandated to visit aged care homes during the height of COVID-19, and it’s normal to ask people to get vaccinated before they can see a new baby,” he said.
“We just need to normalise this vaccine too as a standard process, and we know when we don’t, it kills people.”
Do we know if the AZ vaccine is TGA approved for the half-dose + full-dose regime that produced 90% protection? I heard that the half-dose regime was actually a mistake and that it was only a small subset (a couple of thousand participants). Because 60% to 90% effectiveness is a pretty big difference in terms of herd immunity and if it is only approved for the 2 full doses then we shouldn’t really be quoting the 90% value in this context.
Also, Hunt’s statement that herd immunity is typically 60-66% isn’t right is it? Doesn’t it depend on the R-value? My understanding is that the level of vaccination required needs to reduce the effective R-value under 1. So if the unvaccinated R value (Ro) is 3 (i.e. 1 person infects 3 others on average) then over 2 in 3 people (i.e. 66%) needs to be inoculated. But say if the B117 is 70% more transmissible its Ro could be closer to 5 meaning that 4 in 5 people (80%) of people need to be inoculated. Apologies if I have misunderstood this.
And really the R value should ideally be much lower than 1 (and not everyone will get the vaccine) so we may need the > 90% effectiveness of the mRNA vaccines
Speaking as a person who laughs at anti-vaxxers, I nonetheless worry that the AZ effort will turn out to be another Morrison announceable.
He just couldn’t wait to get the AZ, could he? Remember his ‘first in the world’ announcement in mid-August, after which AZ said there was no signed agreement? The problem now is that many Australians will regard the AZ as a poor second or third best option, and pro-vaxers will add themselves to the anti-vaxer crowd, refusing the jab till more of the perceived ‘world’s best’ comes along. Could this be the virological equivalent of the NBN?
But most countries seem to be stuffing it up somehow. Boris has managed to get plenty of Pfizer but is jabbing it in like there’s no tomorrow, blithely ignoring Pfizer’s direction to keep half the shots for a second dose three weeks later.
Virological equivalent of the NBN
Gold.
Anyone with a brain should not be lining up for an experimental Vaccine that’s been rushed out. The deaths already happening have mainly not been reported by MSM. Normally vaccines takes 7-10 YEARS before being deployed. I’m well over 70 & have been up to now getting Flu shot every year- never again. The Flu shots are at most 50% effective & as with ALL Viruses mutate which is why they keep changing the dose.
From now on I’m relying on my own Immune system to protect me. If someone is old and/or with other health problems -then isolate etc. Some interesting facts about Vaccination in the following link -dated Jan 3rd 2021:
What Vaccine Trials? – OffGuardian (off-guardian.org)
The Off Guardian org is perceived as a ‘fake news’ website. Perceived to severely violate basic journalistic standards. It’s full of conspiracy theories and pseudoscience content.
Completely agree. (Other than using a poor source).
The truth is that data has been manipulated from day one to create fear and panic.
Add to that, the fact that any sensible queries have been thrown into the conspiracy theory bucket, and serious minds such as Dr. Mike Yeadon have been silenced by the censors makes me believe that the agenda at play is not to protect, but to control and to profit.